Section 1: Housing needs, trends and prospects

UNITED NATIONS CENTRE FOR HOUSING, BUILDING AND PLANNING

THE TOTAL HOUSING output of the industrialized countries during the decade 1958-67 exceeded 77 million units, and an estimated average annual rate of completions of about 7.5 dwellings per thousand inhabitants (see Table 1). Overall, this was no doubt a record output compared with previous decades, although advances were not uniform in all countries and regions, nor indeed did they all display an increasing rate of output during this period. Complete data for housing construction in developing countries during the 1960s are not available. It is estimated, however, that the average number of dwellings constructed per year in the developing world was two to three units per thousand inhabitants. It must be pointed out that this estimate takes into account only those dwellings built under some kind of municipal control, and does not include " spontaneous" dwellings, built mainly in rural areas where controls practically do not exist in many nations. Nevertheless, the housing output for the past decade both in industrialized and developing countries has been far from the expected performance of ten units per thousand inhabitants proposed as a target for the decade.¹

(¹ For analytical studies of the European housing situation the reader is referred to (1) and (2) in the references.)

In fact, only a handful of countries completed ten or more dwellings per thousand inhabitants per year. Among these were Japan, Sweden, Switzerland, the U.S.S.R. and the Federal Republic of Germany. The more developed areas built roughly 7 million dwellings per year instead of 9.5 million, and the less developed areas 8 million instead of 27 million. In percentage terms, developed countries should have built 35.7 percent more (that is, 1.35 times the actual output), and developing countries 237 percent more (or 3.4 times the actual number built). The gross estimation for the world shows that the output of all countries should have been two and a half times the actual production (36.5 million instead of 15 million) to reach the proposed objective.

Present housing situation

FACTORS AFFECTING HOUSING REQUIREMENTS

The relative magnitude of the various components that constitute quantitative housing needs for a given period varies in different countries. The main elements are the following:

1. Growth of population, changes in family structure and economic patterns.
2. Internal migration.
3. Replacement of old stock (dilapidation, obsolescence, urban renewal, natural calamities).
4. Relief of current shortage (sharing of dwellings and overcrowding).
5. Creation of an adequate housing reserve for mobility and seasonal occupancy.

TABLE 1. A SUMMARY OF TOTAL DWELLINGS COMPLETED IN INDUSTRIALIZED COUNTRIES¹ FROM 1958 TO 1967

	Total dwellings completed
	Thousands
Europe²	30 077.1
of which:
Northern Europe	(1 778.9)
United Kingdom and Ireland	(3 585.3)
European Economic Community	(13 854.1)
Central Europe	(1 855.3)
Southern Europe	(3 523.5)
Eastern Europe	(5 480.0)
U.S.S.R.	23 791.0
United States	14320.2
Canada	1 402.0
Australia	998.0
New Zealand³	233.0
Japan	6 396.0
TOTAL	77 217.3

SOURCE: Calculated from the tables for the different subregions and countries, where sources of information are indicated.

¹ Excluding South Africa, for which adequate data were not available.
² Excluding U.S.S.R.- ³ Period for New Zealand, 1960/61-1968/69.

This paper has been prepared by the United Nations Centre for Housing, Building and Planning (UNCHBP) in collaboration with EZRA LEVIN, ARIBA, deputy director and chief architect of the Timber Research and Development Association (TRADA), United Kingdom.

Population growth

The estimate of the likely size and natural rate of growth of a country's population in any given period is generally determined by well-established statistical methods applied to data derived from periodic censuses, the registration of births, deaths and marriages and observed changes in such important demographic factors as fertility and longevity and rates of marriages and divorce in different age groups, which may in turn be linked with standards of living and various social and economic factors, including housing conditions.² Rates of natural increase of population vary considerably between countries and also from period to period. Industrialization and urbanization generally lead to lower rates of growth than those prevailing in predominantly agrarian societies.

(²In estimates for some countries this is provided for separately because of the difficulty in forecasting rates of migration with any degree of accuracy.)

Table 2 gives general figures of population in the world and for the major developed and developing areas for 20 year periods from 1920 to the year 2000. It shows an estimated annual rate of growth of 0.8 percent in population of countries in more developed areas from 1940 to 1960; an expected peak growth of 1.1 percent in those countries for the period 1960-80 and a slight decline to 0.9 percent between 1980 and 2000. The most obvious cause of housing shortage in developing countries is the rapid growth of population. Rates of natural increase in those countries are two to four times as high as those prevailing in more advanced countries (3). They were 1.6 percent from 1940 to 1960; they are expected to be 2.2 percent during the period 1960-80 and to decline to 2.0 percent from 1980 to 2000. According to this table, it is expected that world population will double from 1960 to the year 2000 from 3 000 million to about 6 000 million. Urban areas will grow at much higher rates. About 340 million additional people crowded into cities in the 1960s. In the 1970s an estimated 450 million more people will be in need of urban space. Conservative estimates indicate that the world's urban population will rise from 1 330 million in 1970 to 3 090 million in 2000, an increase equivalent to 1 760 new cities the size of Brussels.

According to United Nations demographic projections, rural areas in less developed countries will grow from 1 915 million in 1970 to 2 765 million in 2000, an increase of 850 million people. The bulk of this increase. 540 million, is expected in south Asia. Given the overcrowded conditions depressing levels of subsistence in a large part of this region, 540 million people added to the present rural population of 860 million could create great social upheaval in the process.

Without considering other factors for housing needs, such as the accumulated deficit of housing stock, internal migration to cities and others, figures of projected growth of population indicate the extraordinary size and extreme importance that new housing provision has and will have in the years to come.

Internal migration

Large-scale migration of labour from farm to factory, from countryside to town, is a feature of all industrialized and rapidly industrializing countries. It adds new dimensions to the problems of housing not only by splitting up large families, thereby creating new households, but also through geographical redistribution of population.

Table 2 and Figure 1 show the decline of agricultural populations all over the world. The rural population will probably predominate over the urban until the end of the century, but half the world population will be living in cities in the year 2000.

Apart from rural migration, there is also-particularly in the older established industrial countries-a flow of population from centres of old and declining industries to the location of new and flourishing ones, often despite policies designed to bolster up the depressed areas. The effects of this movement are similar to those of agricultural migration in that they create an imbalance in the distribution of housing accommodation.

International migration

International migration is a factor to be added to the rate of natural increase. Contrary to the large movement of migrants from Europe to many developing countries in the 1940s and 1950s, the trend during the 1960s has been from the less developed to the more advanced nations.

FIGURE 1.- Proportions of urban and rural populations, world and major regions, 1920, 1960 and 2000. 100 = total population. For source, dates of reference, and notes, see Table 2.

TABLE 2. - POPULATION GROWTH, URBAN ' AND RURAL, 1920 TO 2000

SOURCE: United Nations Statistical Office (6).
¹Excluding countries for which data with defined urban population could not be found.

Within Europe, international migration was the main cause of population growth, particularly in the Federal Republic of Germany, France and Switzerland. In the Federal Republic of Germany from 1952-59, immigration from Italy amounted to 42 percent of the natural increase of population. Austria and Portugal lost similar percentages of their populations, and net emigration from Ireland was 50 percent higher than the natural increase (4). From Spain it was reported as recently as 1969 that about 850000 Spanish workers were abroad. Since most migrants are in the younger age groups, the effect on household formation is more pronounced than mere numbers suggest. This flow produces a negligible relief in housing needs in the migrants' countries of origin, at the same time creating housing demand in the recipient countries.

Formation of households

The next stage in assessing housing needs due to growth is to establish the distribution of the population into households requiring separate accommodation. There is evidence from practically all the industrializing countries that the rate of household formation is much faster than the rate of population growth. A striking example is Japan where, according to the 1965 census, the population increased by 10.1 percent compared with the previous 1955 census, while the number of separate households increased by 34 percent during the same period (5).

This rapid increase in household formation generally far exceeds population growth and increases housing needs accordingly. A number of demographic and social factors appear to be responsible for it in varying degrees in different industrialized countries. Among those most frequently quoted and most readily quantified are: greater longevity (due to higher living standards, improved hygiene and medical services); more marriages; and the increasing proportion of the single, divorced and widowed, who tend to set up home on their own. The most important effect of these factors on housing is the growth in demand for small dwellings as distinct from family houses, with the consequent trend toward multidwelling houses.

According to a study prepared by the Economic Commission for Europe (1), estimated future housing requirements arising from natural increase of households range between 40 and 50 percent of total requirements for the period 1960-80 in the majority of European countries. The sizes of private households (persons per household) according to 1960 censuses for major world areas (6) were as follows:

Developed regions		Developing regions
Europe	3.3	Africa	5.1
North America	3.3	Asia	5.2
Oceania	4.5	South America	5.0
Average	3.3	Average	5.1

The dwelling/household rate in 1960 was 95 percent in developed areas, and is estimated at 70 percent in developing areas (7). The average household for the next 30 years is expected to decrease from 3.3 to 2.7 persons in developed areas and from 5.1 to 4.5 in major developing areas (8).

Replacement requirements

In older industrialized countries a relatively large proportion of new dwellings replaces old structures that are beyond repair or unfit for habitation by modern standards. It is therefore worth noting that the most industrialized countries, in spite of their record housing output during the last decade, add only something like 1.5 to 2.5 percent to their total housing stock every year, thus changing it very slowly.

If replacement needs are taken as a proportion of annual housing requirements, and not in proportion to existing housing stock, it is interesting to observe how little these replacement requirements in industrialized areas differ from those in less industrialized areas, although they are considerable in both cases (Table 3).

Slum clearance or removal of dilapidated buildings accounts prominently in the building requirements and programmes of most industrialized countries and special legislative, financial and administrative measures have been taken in several countries to accelerate this process.

Improvements and maintenance

The replacement component of national housing requirements, however, is by its very nature less pressing and more subject to arbitrary classification. There remains a large stock of houses which, although deficient in terms of sanitary amenities and other modern equipment, are structurally. sound and capable of renovation at lower cost than replacement. It has been suggested that dwellings generally require rehabilitation after a period of 20 to 30 years (10).

TABLE 3.- ESTIMATED ANNUAL REPLACEMENTS AS PERCENTAGE OF TOTAL AVERAGE ANNUAL HOUSING REQUIREMENTS

	Percentage	Period
Europe	33.0-50.0	1961 -80
United States	25.0	1967-77
Japan.	40.0	1965-85
Africa	36.3	1960-65
Asia.	40.0	1960-65
Latin America	33.3	1960-65

Source: United Nations (9).

Efforts are being made in this connexion to reduce replacement of housing stock by improving the condition of existing unfit dwellings in slums, and even in squatter settlements, instead of their total replacement. Indeed, although economy is the prime consideration, social considerations also lead to this approach.

It is clear that the laying down of standards for determining fitness for habitation, and deciding when dwellings are beyond the stage of justifiable rehabilitation are subjective and thus more susceptible of judgement by governments and housing authorities than the statistical determination of new housing needs. Estimates for replacement requirements should be used with caution in view of other possible approaches to the improvement of housing conditions. Rehabilitation versus replacement is thus largely a matter of economics and policy decisions. It depends to a large extent on the cost of bringing obsolescent dwellings up to an accepted standard for an estimated new period of life, compared with the cost of new building.

Second homes

Numerical data on the growth of " second homes" (seasonal or holiday homes) in developed countries are scarce. There is no doubt, however, that with the overall improvement in the general housing situation in the 1960s, the rise in standards of living, and the increase in leisure time and paid holidays, there has been an appreciable expansion of holiday accommodation in general and in the acquisition or building of holiday or seasonal second homes in particular. This movement is of particular interest to the forest products industries, since second homes are generally erected in rural areas, and are frequently wooden structures.

Dwelling shortages

A very common aspect of shortage, and one that is given only scant attention in most countries, is that of overcrowding. It is normally linked with the sharing of dwellings by more than one family. Statistics reflect more precisely the primary need for more rooms per household, although they do not yet reflect the subsequent qualitative requirements of more living space per individual in terms of floor area. They show that countries having an average of two or more persons per room usually also have a high percentage of dwellings with three or more persons per room. While such high average densities have been overcome in all developed countries, in fact more than half the countries of Asia, Africa and Latin America fall into the category of more than two persons per room. In these countries the average proportion of dwellings with three or more occupants is over 40 percent, which is an impressive indicator of their dwelling shortages.

Effective demand

Estimates of needs, however carefully established and even when taking into account demographic and social changes, existing shortages, and requirements for modernization and replacements, cannot in themselves provide an adequate guide to likely future achievements, although they may underline shortcomings in past performance. Realistic housing plans must be based on adequacy of resources for both supply and demand. On the supply side, the problem is mainly that of the ability of the building and supply industries to meet the demands placed on them. Later this paper is largely concerned with the changing position of forest products industries in the light of a variety of factors which affect these demands, but here it is more concerned with the ability of the economy of a country as a whole to sustain an effective demand³ through adequate investment in housing, related to the growth of the economy and demands of other sectors of investment.

(³Effective demand "expresses a desire for housing or a desire for larger or better equipped homes supported by the economic ability to support the desire" (13).)

Table 4 shows a generally higher rate of investment in housing for western European countries and the United States in the decade 1958-67, consistent with the higher output of dwellings. As would be expected, the decline in housing output in the United States in the 1960s is reflected in the drop in percentage of investment in housing (out of total GNP) from a moderate 4.9 in 1958 to a low 3.3 in 1967. Italy, Greece and Switzerland were the only countries where investment in housing as a percentage of GNP exceeded 7 percent around the mid-1960s. Most western European countries show little variation in the percentage of annual investment.

Table 5 gives the ratio of investment in dwellings to gross domestic product and to gross domestic fixed capital formation in the two periods 1960-62 and 1966-68 for a number of developing countries. Although information for African countries is very limited, it can be said that, with two or three exceptions, investment ratios in housing by countries listed decreased by the end of the last decade.

Housing investment figures in developing countries reflect the low production of dwellings, and the increasing backlog in housing stock accumulated during the decade.

Finally, it is necessary to consider physical resources: the capacity of the building and supply industries to meet housing requirements, particularly in the light of demands by other sectors of construction in expanding economies. In a number of European countries, failure to achieve targets in the 1960s could be attributed to an overextended building industry and competition from other and more profitable construction sectors.⁴ On the other hand, certain countries that suffered a relative decline in house building in the later 1960s (such as Italy) indicated that this was due to lack of buying capacity and not to overstretched building capacity.

(⁴ For example, the restrictions imposed on office buildings in the United Kingdom to divert labour and materials toward housing, and the reported competition from industrial buildings in Czechoslovakia. Shortage of labour, particularly of skilled craftsmen, was reported from a number of countries as a limiting factor and an incentive to industrialized methods of building.)

The building industry in less industrialized areas has a very limited capacity. Lacking a steady demand, it has not developed. The situation with regard to local production of building materials is particularly important. Some African countries have used up to 50 percent imported materials in construction. This and other related factors have produced a serious drain on the national economy in terms of foreign currency, have increased construction costs and reduced the industry's capacity for expansion.

HOUSING TYPES AND STANDARDS

The social and demographic changes induced by industrialization and urbanization have resulted not only in increased need and demand for housing in quantitative terms, but also in a changing pattern of geographical distribution and in the types and standards of dwellings required.

Slums and uncontrolled settlements

While population in developing countries usually grows at 2 to 3 percent annually, and many city populations grow at rates exceeding 6 percent, slums and uncontrolled settlements in urban areas commonly grow at a rate of 12 percent, and sometimes exceed 20 percent (8).

People migrating from rural areas to towns and cities in developing countries find accommodation in two principal ways: by moving into central low-income areas, causing a rapid increase of living densities and extending and intensifying slum conditions; and by invading vacant land in peripheral areas. Although derived from different sources with different terminology, the following figures for some selected cities illustrate the slum and squatter problem in quantitative terms.

Country	City	Year	Percentage of city population in slums and uncontrolled settlements
Brazil	Rio de Janeiro	1961	27
Brazil	Recife	1961	50
Chile	Santiago	1964	25
Mexico	Mexico City	1966	46
Colombia	Buenaventura	1964	80
Philippines	Manila	1968	35
India	Calcutta	1961	33
Pakistan	Karachi	1968	27
Senegal	Dakar	1969	30
Tanzania	Dar es Salaam	1968	34
Zambia	Lusaka	1967	27

Rural dwelling construction

Information on the amount of housing construction in rural areas is especially important from the viewpoint of wood use. Rural housing in many countries is strongly traditional in building methods. It differs from urban in that rural dwellings are more likely to be single-family houses; they are likely to be erected by smaller builders, with local materials and conventional methods; they are usually owner-occupied, and often owner-built.⁵

[⁵Thus emphasizing lack of sophistication in design and materials. An interesting correlation between the percentage of rural population and of dwellings built by individuals in eastern Europe and the U.S.S.R is shown on page 107 of (2).]

Given the enormous population growth to be expected in both rural and urban areas, the structure of rural settlements will have to change in order to accommodate the additional people and relieve the migration pressure on cities. The characteristics of present housing construction will have to be adapted to meet demand. The use of wood and other local materials will consequently need to be more industrialized.

Single- versus multidwelling buildings

An important consequence of industrialization and urbanization, as far as the pattern of residential accommodation in many developed countries is concerned, has undoubtedly been the marked increase in the number and percentage of units provided in multidwelling buildings. The intensity of wood utilization per dwelling or unit of area is everywhere much lower in blocks of flats than in single-family houses. Classifications and precise definitions differ between countries, and the statistics for some include intermediate combinations of dwellings (for example, row-houses, duplex and formplex houses, etc.). These differences make direct comparisons difficult, but do not obscure the general trends, which appear in each country.

In Europe, this trend toward multidwelling buildings and its impact on wood consumption in housing were stressed in FAO/ECE studies in the late 1950s and early 1960s (14, 15). It was not a continuous and uniform development. Whereas 1960 showed an advance in multidwelling construction in 14 of the 16 selected European countries, and only Denmark and the Federal Republic of Germany showed a reversal of the trend, the position in 1967 had changed and six of the countries showed a lower percentage of multidwelling construction than in 1960. The most notable decline was in Sweden, Norway and Yugoslavia; on the other hand other Mediterranean countries, as well as Austria, Finland and Belgium, showed further substantial increases in the percentage of multidwelling units. In the United Kingdom there was also a considerable increase in multidwelling construction, but the percentage remained low (29 percent) compared with most European countries (see Table 6).

In eastern Europe, the German Democratic Republic and Hungary marked the steepest decline in single- and two-family units, and by the end of the decade only a few single-or double-dwelling houses were being built in these countries.

It is interesting to note a close correlation between these trends and the rates of rural versus urban house building. In general, countries with continuing or increasing preferences for single- or double-family houses also show good rates of rural building. The majority of these houses were erected in suburban areas within the administrative control of towns and cities, or in new "overspill" towns.

Outside Europe, the development of multistorey building has been fairly general. In Canada, the rise in dwelling construction during the 1960s by nearly 60 percent was attributable entirely to the growth of multiple dwellings, whose annual output trebled.

In the United States, multifamily housing in the late 1920s already accounted for nearly a third of the dwelling units built, but in the 1930s and 1940s it dropped to around 12 percent of all new house construction. During the past two decades, it had again grown in proportion, attained about 30 percent of the total in 1962/63 and in 1968 about 40 percent. During the period 1959-68, however, the average percentage was just over 31 percent of total construction.

In Australia, there was also a marked increase in the number of apartments built annually, from a negligible 2.9 thousand (4 percent of total completions) in 1956/57 to 39.1 thousand (30 percent of total) in 1968/69. However, during the same period, annual construction of single-family houses almost doubled, in contrast to the development in North America.

In Japan, there has also been a marked swing toward multidwelling houses, despite the acknowledged preference of most people for the traditional detached house and garden.⁶

[⁶ According to a 1965 report by Hiraga and Furukawa, major demand continues to be for the individual custom-built house, provided in the main by the private sector (by far the largest) of the building industry (16).]

In the developing countries, a marked distinction must be made between low-cost housing and middle- and high-income housing. While low-cost housing has been predominantly single-family, apartment buildings for middle- and high-income families in large cities have been built intensively in many of these countries. However, there have been several exceptions to this general trend, such as the blocks of apartments for low-income tenants built during the 1960s in Venezuela, India, Singapore and Hong Kong, which have been the subject of intensive study and controversy. In some projects, developing countries have experimented with European heavy concrete prefabrication systems. But, usually, multifamily housing has been built of traditional reinforced concrete with brick or concrete block cladding.

TABLE 4.- GROSS FIXED CAPITAL FORMATION IN HOUSING¹ IN WESTERN EUROPEAN COUNTRIES AND THE UNITED STATES, 1958 TO 1961

SOURCE: United Nations Economic Commission for Europe (23).

(¹ Based on 1967 market prices. _ 2 Gross fixed capital formation in rousing: A = as a percentage of gross national product; B = as a percentage of total gross fixed capital formation: C = as a percentage of gross fixed capital formation in construction.)

TABLE 5. - INVESTMENT IN DWELLINGS IN DEVELOPING COUNTRIES, 1960-68

	Investment in dwellings as percentage of
	Gross domestic product		Gross domestic fixed capital formation
	1960-62¹	1966-68²	1960-62¹	1966-68²
LATIN AMERICA
Bolivia	0.7	1.9	4.4	9.4
Chile	2.8	2.7	17.5	17.7
Costa Rica	4.9	3.8	25.7	18.5
El Salvador	2.7	2.1	21.5	13.8
Guatemala	1.6	1.8	15.7	14.6
Honduras	3.8	4.0	31.0	24.7
Jamaica	3.1	3.0	15.5	14.8
Nicaragua	19	1.7	10.5	10.5
Panama	3.2	4.2	20.0	20.8
Venezuela	1.8	3.2	12.2	18.6
AFRICA
Kenya	2.0	2.3	16.0	14.4
Lesotho	-	3.2	-	30.6
Mauritius	7.8	3.7	33.0	23.7
Sierra Leone	-	2.6	-	18.9
Sudan	1.6	-	11.9	-
Swaziland	-	1.7	-	8.0
Togo	-	1.5	-	12.8
Tunisia	2.3	2.1	12.0	9.1
ASIA
Jordan	5.4	3.3	32.0	22.7
Khmer Republic	6.1	4.4	35.9	28.0
Korea, Republic of	1.9	2.0	15A	10.6
Malaysia	1.8	1.8	12.3	10.6
Philippines	2.2	2.2	18.1	13.2
Singapore	1.9	3.0	23.1	22.2
Syria	3.9	2.6	21.5	15.2
Taiwan	1.9	2.3	11.9	11.0
Thailand	1.8	1.7	11.7	7.3

¹1961-63, Syria; 1962 only, Khmer Republic; 1964 only, Kenya; 1965 only, Nicaragua -.² 1963-64, Togo; 1%466, Lesotho, Mlaysia, Sierra Leone 1965-67, Costa Rica, El Salvador, Jamaica, Korea (Rep. of), Mauritius, Syria, Thailand, Tunisia 1966 only, Khmer Republic; 1967 only, Swaziland; 1968 only, Kenya, Nicaragua.

Although complete data are not available for developing areas on the distribution of housing units between single and multidwelling types, single-family housing unquestionably predominates.

Size and height of buildings

The trend in most industrialized countries toward the provision of a fairly high, and in some cases rapidly increasing, proportion of housing in multiple-dwelling units has been generally accepted as one of the main reasons for the overall decline in the use of wood-based products, because of natural as well as legislative limitations on the use of wood. It is important, however, to consider recent trends in size and height of multidwelling buildings, since these characteristics have a great bearing not only on the extent of present utilization of wood, but also on future possibilities, as the experience of some countries demonstrates. The vision of towering blocks of flats dominating the housing scene is true for only a minority of countries. Even where multidwelling units predominate, the majority are provided in low- or medium-rise buildings up to four storeys in height, the tall tower blocks or slab buildings being reserved for high-density redevelopment areas or as dominant features in new neighbourhood units. Reasons for limiting the " verticalization" of dwellings are both social and economic. Many studies have shown diminishing returns (in terms of density of persons) of dwellings per unit of ground area by adding storeys, if adequate standards of daylighting, space about the building, circulation requirements, and so on, are observed (17, 18).

It was reported from Japan that the cost per unit of floor area in apartment buildings of six or seven storeys was 30 to 40 percent higher than that in buildings of three or four storeys. Although the actual figures depend on methods of construction and national conditions, similar trends of increasing costs with increased height have also been reported from other countries, the steepest increase coming at the level where installation of lifts becomes necessary.⁷

(⁷ Studies of the height and density of residential buildings, and their effect on the use of wood for structural elements, are discussed in more detail in Section 5.)

Size of dwellings

With the trend in many countries toward more apartment dwellings, which are generally smaller than detached or semidetached family houses, it is pertinent to consider the effect of these trends on the average size of dwelling, since this will obviously affect the demand on building materials.

Earlier FAO/ECE studies in trends of utilization of wood products in European housing did not indicate any clear general growth in either dwelling size or number of rooms during the 1950s (14). Similarly, an American study of 1954 predicted stabilization of the average single-family house in the United States at around 100 square metres from 1960 onward, following an historic decline from the 1920s to a low level in 1950, and a slight rise again to 90 square metres in 1953. The grounds suggested were both demographic (decline of family size) and economic (increase in building costs and equipment in the home) (19). During the 1960s there was clear evidence from both continents that the average dwelling size had grown significantly.

A general conclusion which may be drawn from this review of trends in dwelling size is that space standards tend to increase and, given continued expansion of national economies and personal incomes, can be expected to continue to rise in most, if not all, industrialized countries. The annual rate of growth in floor areas is likely to be between 0.5 and 2 percent, and a number of national reports on future house building indicate increased dwelling sizes. For example, in Czechoslovakia, where the average useful area was 39.6 square metres in 1967, it was expected to attain a figure between 42 and 49 square metres by 1970.

TABLE 6.- TRENDS IN CONSTRUCTION OF ONE - AND TWO-DWELLING HOUSES EUROPE, 1958 AND 1967

	1958		1967		Trend
	Total dwellings built	Percent of one- and two-dwelling houses	Total dwellings built	Percent of one- and two-dwelling houses
COUNTRIES SHOWING INCREASE
Denmark	20 000	51.0	43 800	62.6	Absolute and relative growth
France	332 000	32.0	466 200	34.3
Norway	26 000	66.7	28 000	70.8
Sweden	62 000	27.9	100 200	28.2
Switzerland	20 600	14.6	55 000	15.9
Yugoslavia	61 700	55.4	127600	63.0
Belgium	39 600	73.2	63 600	60.0	Absolute but not relative growth
Germany, Fed. Rep. of	450 000	46.8	524 300	45.7
Iceland	1 400	60.0	1 800	51.6
Ireland	6 700	95.0	10 800	81.6
Netherlands	89 000	57.0	127 400	55.0
United Kingdom¹	303 200	78.0	415 500	71.1
Bulgaria	39600	73.2	63600	60.0	Absolute growth despite relative decline
Czechoslovakia	53 400	31.5	83 000	23.9
COUNTRIES SHOWING DECLINE
Austria	39 900	45.0	47 700	36.2	Marked relative decline, absolute decline alleviated by total growth in dwelling construction
Finland	30000	50.3	36500	34.4
Greece	52200	90.0	64800	39.0	Absolute and rapid relative decline
Turkey	38 300	90.4	50 200	41.9
Spain²	119 000	12.5	264 000	4.8	Rapid relative decline but small absolute decline due to large total growth in dwelling construction
German Dem. Rep.	63 300	9.0	76 300	0.0	Absolute and relative decline
Hungary	11300	3.5	21 600	1.5	Appreciable relative decline, but small absolute decline

¹1961.-²1960.

In the less industrialized countries, as the majority of dwellings built have been single-family units, and the number of persons per household has remained approximately constant, changes in area per dwelling have been a result of factors other than those prevailing in developed countries. The most important arc economic limitations, cultural patterns of living and climatic conditions.

Economic limitations have severely reduced the size of dwellings to around 10 square metres of total area per person (in exceptional cases such as Hong Kong the median square feet per person is 43, about 4 square metres) (20). In some developing countries, government low-cost housing projects (for example, in Chile) have gone even farther, providing a core house of one or two rooms for families as a first stage, and assisting them in the addition of rooms in two further stages until the dwelling is completed.

Small houses and low-rise dwelling construction

Although data are rather sketchy and relate to only a few countries, it can be said that small houses, in rows, terraces, chains, patio arrangements or other groupings, can achieve high densities without sacrificing the privacy of approach and individual garden of the detached house. Such forms of attached construction are bound to develop further in most countries, particularly those with densely populated conurbations. They seem to offer the half-way solution between the detached one-family house and the apartment block, acceptable on both social and economic grounds, at least for suburban developments.⁸

(⁸ In the United Kingdom, ceiling prices laid down by the Ministry of Housing and Local Government for the purpose of loan sanction for local authority housing are pegged to densities and tend to favour low-rise development on grounds of economy in cost.)

An experimental low-cost housing project has been initiated in Peru as a result of an international competition among leading local and foreign architects. This project is being carried out by the Government of Peru with the assistance of the United Nations. Because of the purpose of the project, and the prestige of the professionals involved, it may be considered the most up-to-date approach to low-cost housing for developing countries, and may serve to illustrate current trends in types of dwelling. The brief for the competition states that each dwelling lot should be between 80 and 150 square metres, of which the dwelling should occupy between 60 and 120 square metres (including all floors); the buildings, initially of one or two storeys, should be structurally able to carry a third floor. The resources of the competition will be "concentrated to explore and develop techniques in architecture and construction within the general area of low-rise, fairly high-density and compact housing in terrace, row and other formation. It is not feasible to consider other alternatives, such as multistoried buildings." This project follows the present tendency of concentrating one-, two- or three-storey houses in clusters on small plots that can be found in several other European and American examples.

Rise in amenities and equipment

Quite apart from the growing concern in most industrialized countries with improving general neighbourhood amenities in housing estates,⁹ the rise in standards, reflected everywhere in larger dwellings, affected also the equipment within the home. Standards naturally vary between countries according to past traditions and present wealth, but seemed to be rising steadily everywhere. In many countries minimum standards for the amenities installed in dwellings are laid down in building regulations or codes, particularly for subsidized or otherwise publicly-assisted houses.

(⁹ Estate development still presents problems, particularly with regard to sewerage and drainage, especially in some fast-growing and recently industrialized economies. In Japan, this is still a major problem, and it was reported recently that only 20 percent of dwellings in the metropolitan areas were connected to public sewers.)

The rising standards of amenities and equipment have general effects. First, building costs increase considerably (more rapidly than the areas of accommodation), thereby affecting the total programme of house construction possible within the national housing budget. Second, the gap widens between new and old housing stock, rendering the latter more unacceptable. Finally, to the extent that amenities include cupboards and built-in furniture, demand for joinery materials increases, in the first instance wood-based products. The growth in this last category has been general both in developed and developing countries and particularly in North America and the Scandinavian countries.

On a more modest scale, the comparison of amenities in dwellings completed in Czechoslovakia in 1967 with standards in the total stock of dwellings (average age 53 years) is illuminating Table 7)

A review of the recent world situation with regard to amenities and equipment shows a complete range of development from bare living space to the most advanced standards known today. The historical process of improvement in its various stages can be summarized as follows:

(a) toilet facilities outside the house (latrine);
(b) improvement of kitchen facilities inside the house by adding sink with running water;
(c) bathroom brought into the main body of the house;
(d) built-in work table and elementary storage space in the kitchen;
(e) complete installation of electricity, running water and sewage systems for kitchen and bathroom;
(f) water heater in temperate and cold climates;
(g) kitchen cabinets;
(h) cupboards and closets in bedrooms and other living areas of the house.

TABLE 7. - AMENITIES IN TOTAL AND NEW (1967) DWELLING STOCK IN CZECHOSLOVAKIA

Total stock		1967 completions¹
Amenities	Dwellings with amenity	Amenities	Dwellings with amenity
	Percent		Percent
Central or district heating	8.1	Central heating	95.8
Bathroom	33 3	Hot water supply	96.0
Gas supply	19 7	Gas supply	85.4
Water supply within apartment	49.1	Gas central heating and hot water	84 6
Electricity	97.3	Laundry with modern equipment	36.4
Inside WC	29.0	Built-in furniture(at least in hall)	94.7

SOURCE: Research Institute for Building and Architecture, Prague, 1969.

¹ Excluding private sector: state enterprise or agricultural dwellings.

From the point of view of wood, stages (g) and (h) are the ones that potentially require the maximum use of this material, even in places where timber is not the basic building material.

Most housing projects built during the 1960s comply at least with stage (e), although in some examples in Africa the bathroom still remains separated from the house. The majority of new projects in Latin America include stage (g) kitchen cabinets, and a large proportion have been designed with some cupboards in other parts of the dwelling (h).

Cabinet work and built-in furniture, in addition to doors and windows, have therefore been the wood items in greatest demand, even in places where wood construction does not prevail. However, this has not been matched in general by a parallel development of the joinery industry.

Future trends in housing demand, types and standards

EFFECT OF DEMOGRAPHIC FACTORS ON FUTURE REQUIREMENTS

From the earlier discussion of demographic and social trends it is clear that while one cannot talk of a population explosion as far as the industrialized countries are concerned, there are definite indications of a " household explosion." As the rate of household formation in many countries is several times that of population growth, it constitutes the main component in future housing requirements.

A very tentative estimate by the United Nations Centre for Housing, Building and Planning (UNCHBP) assumes that by the year 2000 there will be one dwelling per household in more developed areas, and 95 dwellings per hundred households in less developed areas (8). Table 8 indicates a tentative estimate of the dwelling stock which would be required to meet the increase of households by the year 2000.

PROJECTIONS OF HOUSING SUPPLY

Table 9 shows total projected new dwelling construction for 1971-80, and indicates housing requirements adjusted to take into account likely demand and past performance in industrialized countries. According to these estimates, total housing output in the 1970s for the developed countries is likely to be about 110 million dwelling units, an increase of nearly 40 percent over the previous decade. The rate of dwelling construction per thousand inhabitants was 8.6 in 1970, and it is estimated that this will grow gradually to about 10.9 in 1980.

Projections for the less industrialized countries are uncertain. The size of demand for dwellings will depend mostly on government priorities given to the housing sector during the decade. It is expected that social development and higher national income will permit governments to assign more preeminence to housing as an indirect factor of productivity. The limited data available and the nature of the assumptions on which calculations are based preclude precise estimates of future housing needs. Table 10 is a tentative estimate of the number of dwellings which should be constructed between 1970 and 2000 for the natural increase of households and for replacement requirements.

TABLE 9. - PAST AND PROJECTED NEW DWELLING CONSTRUCTION IN DEVELOPED COUNTRIES, 1960s AND 1970s

	1960s	1970s	Approximate increase
	Millions		Percent
Europe.	30.1	40.6	34
of which:
Northern Europe	(1.8)	(2.4)	(33)
United Kingdom and Ireland	(3.6)	(4.3)	(19)
European Economic Community	(13.9)	(16.8)	(20)
Central Europe	(1.9)	(2.9)	(52)
Southern Europe	(3.5)	(6.5)	(90)
Eastern Europe¹	(5.4)	(7.7)	(43)
U.S.S.R.	24.0	31.4	27
United States	214.3	319.5	20
Canada	1.4	2.4	70
Australia	1.0	1.5	50
New Zealand	0.23	0.3	30
Japan	6.4	14.0	127
TOTAL	477.2	109.7	39

SOURCE: Table prepared by TRADA from various national sources.

¹ Excluding U.S.S.R, - ²16.3 million including mobile homes. - ³ Based on U.S. Forest Service projection (22) which excludes conversions. - ⁴ 79.2 million including mobile homes.

TABLE 8.- TENTATIVE ESTIMATES OF WORLD DWELLING STOCK REQUIREMENTS, 1970-2000

		Developed areas			Developing areas			World total
		1970	2000	Annual average increase	1970	2000	Annual average increase	1970	2000	Annual average increase
				Percent			Percent			Percent
Population (millions)		945	1 266	1.0	2 647	4 864	2.0	3 592	6 130	1.8
Persons per household	min	3.3	2.7	1.0	5.1	45	2.0	4.5	4.0	1.7
	max		3.3			5.1			4.6
Households (millions)	min	280	380	1.7	520	950	2.5	800	1 330	2.2
	max		470			1080			1550
Dwellings per household		0.95	1.0	1.2	0.70	0.95	3.1	0.79	0.97	2.5
Dwelling stock (millions)	min	270	380	1.9	360	900	3.7	630	1280	3.0
	max		470			1030			1500

OURCE: United Nations Bureau of Social Affairs (21).

PROJECTED TRENDS IN HOUSING TYPES AND STANDARDS

Geographical distribution-urban concentration

In those countries where internal migration is still flowing fast as a concomitant of industrialization, urban concentration will continue, and house building in the main metropolitan areas will predominate in the national housing picture. In Sweden, for instance, it is anticipated that housing demand will increase substantially in the Stockholm, Göteborg and Malmö regions. In the northern regions housing will decline, while in others there will be moderate increases. Similarly, in Canada, it is expected that 98 percent of all new dwelling units in the 1970s will be built in the cities. In Japan, new dwelling construction from 1965-85 is expected mainly in the urban areas, where 22.5 million dwellings will be built, as against 7 million in rural areas, in the latter case mostly to replace demolitions.

It has been emphasized that, particularly in the older industrial countries which are already largely urbanized, decentralization is taking place in the form of new suburban development and new overspill towns on the basis of regional planning. This will no doubt continue in the 1970s, with implications for trends in types of housing

The tentative estimates of Table 8 combined with the probable population growth in Table 2 lead to the following conclusions for the period 1970-80:

1. As the population of rural areas decreases in the industrialized countries, most new housing will be built in urban areas. In the less industrialized countries, the increase of population will be, globally speaking, approximately the same in both rural and urban areas (230 million in urban areas compared with 270 million in rural areas). However, as was pointed out earlier, urban population in east Asia and, particularly. in Latin America will grow much faster than rural population, while rural population in south Asia and

Africa will continue to grow more than urban population. New housing will have to be distributed accordingly.

2. World housing stock is expected to increase by about 170 million dwellings, of which approximately 30 mil lion will be built in developed and 140 million in developing areas.¹⁰

(¹⁰ These figures assume a household size of 3.3, a rate of 0.96 dwelling per household, and an increase in number of households from 280 to around 315 million in developed regions; in developing regions, a household size of 5.1, a rate of approximately 0.80 dwelling per household, and an increase in households from 520 to 645 million.)

Single versus multidwelling buildings

Where further heavy urban concentration is expected in industrialized countries housing authorities foresee, as an inevitable consequence, a proportionate rise in multidwelling accommodation. This is attributed chiefly to the growing scarcity and cost of urban building land and the desire to prevent urban sprawl In some cases the need to save agricultural land from suburban encroachment is also mentioned ¹¹ A more serious consideration in some countries is the rise in cost of house ownership compared with that of rental accommodation, which is usually in multidwelling houses.¹² The trend toward smaller families in most countries, including single-person households, also means a growing need for a higher proportion of small dwelling units, conventionally provided in multidwelling and often multistorey blocks (see Table 11).

(¹¹ By the Economics and Statistics Department of the Central Mortgage and Housing Corporation (CMHC) in Canada.)

(¹² The situation in Canada at the end of the 1960s, as ret ported by CMHC.)

The U.S. Department of Agriculture assumed that the growth rate of multidwelling units would reach 35 percent by 1980, and that two-family units would be maintained at about 3 percent of the total. Allowing also for mobile homes and additions by conversions, the projections for 1970-80 are given in Table 12.

The situation in developing countries is less clear and much more difficult to predict. There are some developing countries where due to lack of available land, or topographic limitations, multifamily housing has predominated and will continue to do so during the 1970s. Most other less industrialized areas, however, are expected to produce single-family housing for the majority of the population, reflecting the abundance of land and the lower initial investment required by this kind of structure, particularly when infrastructure is not fully provided. This pattern of small single units also suits the living habits of rural migrants to the city. It is likely that some attempts in terms of building materials-some of them wood-based-and household equipment will be made during the 1970s to improve the situation of slums and squatter settlements in the less industrialized countries, while industrialized countries will show increased demand for mobile houses or second homes.

TABLE 10. - ESTIMATED FUTURE HOUSING REQUIREMENTS, 1970-2000

		Developed areas	Developing areas	World total
		................Millions ..........
Dwellings which should be constructed for:
Natural increase of households ¹	min	110	540	650
	max	200	670	870
Replacement'	min	144	346	490
	max	161	382	543
TOTAL	min	254	886	1 140
	max	361	1 052	1 413

SOURCE: UNCHBP (8).

¹See Table 8.-² It teas been assumed that 1.5 percent or existing housing stock will be replaced each year in the developed areas and 2.0 percent in the developing areas.

TABLE 11. - ESTIMATED DISTRIBUTION OF DWELLINGS BETWEEN ONE- AND TWO DWELLING AND MULTIPLE-DWELLING BUILDINGS IN DEVELOPED COUNTRIES, 1971-80

	Type of dwelling
	One- or two- dwelling houses	Multiple dwelling units
	Average percentage
Europe:
Denmark, Ireland, Netherlands,Norway, Romania,¹ United Kingdom, Yugoslavia	60-80	20-40
Austria, Belgium, Bulgaria,Czechoslovakia, Finland,France, Germany (Fed. Rep. of),Greece, Iceland, Italy,Poland, Sweden, Turkey	20-50	50-80
German Dem. Rep., Hungary,	under	over
Spain, Switzerland	10	90
U.S.S.R.¹	25	75
United States	²65	35
Canada	40	60
New Zealand	65	35
Japan	40	60

¹ Assessments based on trends in percentage of building by private persons, collective farms, and rural population generally - ² Of which 30 percent in form of mobile homes

Standards of accommodation and amenities

The improvement in space standards and amenities, which was a notable feature of housing in the 1960s in industrialized countries, is likely to continue in the coming decade as a result of the continued rise in living standards and incomes. This was emphasized in a number of national reports from developed countries.

1. Greater diversification of dwelling types is required and expected in the 1970s-in particular to cope with the needs of both extremes of households, the large family and the small single-person household. Special types of accommodation for the old and infirm, for the young, and for seasonal and holiday needs are specifically included in many national plans and are in some the subject of experimental research and development. On the basis of the foregoing considerations, and as a working hypothesis for assessing future demand for wood-based products, the estimated percentage distribution between one- and two-dwelling houses and units in multidwelling buildings is shown in Table 11.

2. Increases in the area of dwelling unit are likely everywhere, and in many countries are foreseen in the course of the decade, whatever the type of dwelling.

3. Standards of comfort, amenities and built-in equipment in the home are also likely to rise everywhere.

4. With increasing standards and primary building costs, concern at the rising costs of repairs and maintenance is universal. There is also a growing awareness of the need for greater flexibility in design and construction to permit extensions and modifications at reasonable cost in the course of the life of dwellings. This point is discussed in greater detail later in this paper.

TABLE 12. - UNITED STATES: PROJECTIONS OF DWELLINGS ADDED TO STOCK IN 1970 AND 1980, BY TYPE

Year	All types	New construction				Mobile homes	Conversions
		All starts	One-family	Two-family	Multi-family
	Thousands
1970	1900	1630	1040	60	530	170	100
1980	2200	1920	1180	70	670	180	100

SOURCE: U.S. Forest Service (22)

The large number of dwellings to be built with the limited resources available in developing countries will not permit any substantial improvements in standards during the 1970s. It is expected, however, that more dwellings in these countries will reach minimum acceptable standards during the period.

An important distinction is that between low-rise construction and high-rise multidwelling construction. In most countries, the building materials and techniques predominantly used for these different types of dwelling differ substantially from each other and require separate consideration. Building regulations and codes generally place far greater limits on the use of wood products in multidwelling construction, and thus impose a dichotomy on the house-building industry. In many countries this limitation on wood use extends to single-family houses in urban areas, and in some cases suburban areas as well. When the use of wood is habitually limited to roof structures, windows, doors and cabinet work, as it is in most Latin American countries, such a dichotomy is less notable.

A large sector of the urban population in developing countries lives on illegally occupied land in slums and squatter areas of temporary housing, which is basically made of wood without conforming to local building regulations. Their number is far from negligible (see page 12). These settlements cannot possibly be replaced by orthodox housing in a short period. To alleviate the situation governments will have to aim at the improvement of housing accommodation and the provision of essential services rather than at the provision of new housing. Building requirements should also be lowered and the large market of low-cost, predominantly wood-based building materials needed for improvement should be " legalized" and come under the technical control of municipal authorities.

Small house construction

Industrialized countries build permanent housing to acceptable standards of wood or nonwood materials ac cording to local tradition. Most of the less industrialized countries use brick or concrete materials for permanent housing and wood only for rural or temporary housing.

Developed countries, where timber-frame houses were historically established because of ample resources of wood, particularly softwood, continue to use wood as the main building material for the single-family house. This is the case in the United States, Canada, Japan, Australia, New Zealand, Sweden, Norway and, to a lesser extent, Finland. South and east European countries use instead predominantly masonry construction such as brick, blockwork or hollow tiles. Developing countries build permanent houses primarily of concrete blocks, sometimes of bricks, but as most dwellings are of a less permanent character the highest percentage consists of temporary structures of light materials, predominantly wood or wood products.

Trends in timber-frame construction varied considerably in the 1960s, both where this form predominated in single-family housing and where it constituted a minority. Thus, in the United Slates, 88 percent of all houses built in 1962 were of timber-frame construction; 90 percent of single-family houses in Canada are timber-frame; 98 percent of the houses built in Japan in 1968 were also made of wood. As could be expected, this trend continued to flourish particularly in industrialized countries with large timber resources but, surprisingly. not in all of them. On the other hand, considerable progress with this type of construction was registered in the United Kingdom during the last five or six years, where indigenous timber supplies practically do not exist.

In developing countries, because past output of houses was limited in relation to needs, it would be misleading to base future trends on the actual production of the 1980s. The characteristics of future demand are still open to a choice of new building materials and techniques, if industry offers competitive prices and acceptable quality. The efforts of industry to open these potential new markets should also aim at overcoming the low acceptance and lack of prestige that wood housing usually has in most developing countries because of its connotations as a cheap, temporary, and hazardous type of construction. Nevertheless, although wall elements in permanent housing are based on nonwood materials, timber continues to be used for other structural elements, particularly roofs.

Rural housing in the countries of Africa, Asia and Latin America is built with stone, mud (adobe and daub construction), wood, bamboo and mats. The industries supplying these materials are basically a sum of craftsmen and small enterprises. There is a large field here, too, for improvement and development.

Building materials used in residential construction

A survey of building materials used for the load-bearing structures in houses showed, on the one hand, the continuing importance of tradition and local materials, particularly in small house construction and, on the other, the growing effect of industrialization, especially in multidwelling, high-rise construction.

Small houses with timber load-bearing walls continued to predominate in the low-rise sector in countries rich in forest resources where they had developed traditionally -in North America, Oceania, Japan and, in northern Europe, in Norway and Sweden, with a sharp decline in Finland. Industrialization and rationalization of production ensured further relative growth in some countries (for example, the United States) and also helped their penetration into the housing field in some western European countries, notably the United Kingdom and, to a lesser extent, France and the Federal Republic of Germany. The traditional timber house in central and eastern Europe, and in the forest areas of southern Europe, appeared to be in decline. In Australia the traditional timber bungalow had lost some ground to brickwork, particularly as an external cladding.

Masonry construction was still the most important method of wall construction for small houses in most European countries, except the Scandinavian. New permanent housing in most developing countries was also built with bricks and blocks.

In multistorey construction in Europe and less industrialized regions reinforced concrete in various forms, both in situ and precast, had rapidly become the main material for framework construction, and in many countries for wall panels. In some countries in eastern Europe (Czechoslovakia, the German Democratic Republic) and in the U.S.S.R., the share in total building of large room-sized wall elements in precast concrete grew rapidly. Elsewhere in Europe smaller precast elements or in-situ frames with masonry infills were in greater use. Framed concrete structure gave rise to the development in some western European countries (notably France) of light wood-framed panel walling, but their use was still on a small scale compared to the total volume of multi-storey construction.

Industrialized forms of multistorey construction had not developed on a substantial scale outside Europe. In all other countries brick walls, often with steel or reinforced concrete frames, were reportedly predominant.

Wood-based construction for low- and medium-rise multidwelling houses was conventional in the United States and Japan. In the latter, despite official encouragement of nonwood materials, most multifamily dwelling units in the 1960s were of fire-resisting wood construction. In the United Kingdom too, timber-frame housing of light and competitive construction was started in the late 1960s.

As far as use of wood in roof structures was concerned, the following conclusions were drawn from the fragmentary information supplied:

1. In small houses (both timber-framed and masonry) wooden roof structures continued to predominate and in many countries to monopolize the market. Some decline was registered, however, in southern and eastern Europe and in at least one western European country. In Central America, large-span asbestos-cement sheets, not requiring wood structure, were widely used. Trends in timber roofs were toward lower pitches and more economical structures, using less material.

2. In multidwelling buildings of low- and medium-rise, a variable but in some cases still large proportion of roofs were of wood construction (for example, in the United States and the United Kingdom). Flat reinforced concrete roofs constituted the main alternative, both in developed and developing countries.

3. In high-rise apartment buildings, reinforced concrete appeared to have gained an almost complete monopoly.

Similar differences in dwelling types were observed with regard to extent of wood use in floor construction.

1. For single-family dwellings, interstorey floors were still commonly of wood construction in countries where this type of floor was customary.

2. In low- and medium-rise multidwelling houses, wood-based construction remained predominant in the United States (and possibly also in Japan). In Europe, it lost ground heavily to reinforced concrete in all countries. Developing countries have mainly used reinforced concrete floors.

3. Substitution of concrete for timber in ground floors was already advanced in most industrialized countries in the 1950s, even in single-family houses. It continued in the 1960s in some countries, but in others, especially the United States, and to a smaller extent the United Kingdom, there has been a reversal of the trend toward concrete. Reinforced concrete ground floors predominated in the majority of developing countries.

The construction of partitions was generally closely linked to the methods and materials used in external walls. Stud partitions were common in frame housing everywhere but only a small percentage of light, wood-based partitioning was used in masonry-built houses. In medium-rise garden apartments in the United States, stud framing was also common, but in Europe and all developing countries concrete blocks, bricks and hollow tiles were used to an even greater extent than in single-family housing In high-rise construction wood-based partitions were used to a very minor degree.

The decline of wood use for structural purposes was accompanied by a substantial fall in its use for external finishes and for flooring. Trends in the l960s with regard to wall cladding could be summarized as follows:

1. In timber-frame housing, where weather boarding and similar wood finishes predominated in the past, brick veneer and, to a smaller extent, other nonwood materials gained substantially at the expense of wood. In Australia, in particular, the decline has been fast; the share of weather boarding dropped to 10 percent of total external walling. In the United States it dropped to 40 percent.

2. On the other hand, in countries where frame construction was recently introduced, wood boarding and wood-based panels made some advances (for example, in the United Kingdom and France), but the percentage of total walling in small houses was still small.

3. Lenient building regulations in some countries in northern and western Europe had enabled the development of wood-framed external wall panels and curtain walling, often with wood cladding, for medium-and even high-rise multidwelling buildings.

The use of concrete for structural floors entailed in most countries a decline in wood flooring. The development of more economical hardwood-strip and tile flooring, fixed to wood-based subflooring and underlays. preserved in North America a high percentage of the market for wood flooring. In Czechoslovakia. about one third of total house flooring was wood finished and a similar proportion in single-family houses in France, falling, however. to 10 percent in high-rise apartment buildings. The development of competitive plastic-sheet or tile finishes and of close carpeting stimulated, on the other hand, a growth in the use of wood-based underlays. Wood flooring on concrete slabs has been used extensively in some developing countries.

In contradistinction to the decline in wood flooring, there has been a general growth in the decorative use of wood for internal wall and ceiling finishes, particularly in North America, Scandinavia, and in France and other western and central European countries, especially in single-family and low-rise multifamily dwellings. In high-rise construction, restrictions in building regulations generally reduced usage to small proportions.

In most countries wood joinery continued to maintain and, for many items, to strengthen its position vis-à-vis competitive materials. For internal doors wood-based materials had an almost complete monopoly everywhere, but for external doors a significant proportion of metal doors were used in a number of countries, particularly in high-rise blocks and for garages. Steel door frames gained a dominant position in multistorey buildings in France, whereas in the United Kingdom metal window frames were used to a significant extent, although mainly in high-rise buildings. On the whole, wood window frames appeared to have withstood the pressure of competitive materials in the 1960s, and in many European countries were reported to be gaining ground. However, their use was significantly lower in high-rise construction all over the world, with perhaps the exception of Scandinavia. Wood shutters and blinds lost ground to plastics and aluminium, but in most other internal joinery, particularly in cabinets, as well as in external trim such as fascias and soffits, wood materials appeared to have suffered little from competition.

Some of the loss of structural wood to concrete was regained through the increased use of wood and wood-based panels for shuttering. This was assisted by the development of specially treated or overlaid boards designed for improved surfaces and multiple uses. The use of timber for scaffold boards, planking. strutting and other auxiliary uses also appeared to have maintained a strong position.

TRENDS IN SUBSTITUTION AND UNDERLYING CAUSES

From this review of trends in the use of building materials for residential construction the following main conclusions emerge:

1. There was a fairly general and continued decline in wood usage per dwelling for structural purposes.

2. While some of the reduction could be attributed to more rational and economical design in wood, including the growing use of wood-based panels, most was due to substitution by nonwood materials.

3. Substitution was heaviest in multidwelling and. especially, in multistorey construction.

4. Uses of wood for joinery and decorative purposes generally retained or improved their position, and became more important in total usage.

Many interrelated factors contributed to the general trend of substitution of sawnwood and reduction in wood usage in dwelling construction. The following were probably among the most important:

1. Building codes and regulations, particularly in respect of fire control, generally include provisions which prohibit or severely restrict most structural uses of wood in multidwelling and, in particular, multistorey construction. Most regulations also restrict many decorative uses with increasing severity in the larger and taller buildings.

2. The lack of durability of most common wood species, particularly sapwood, in positions of severe exposure or inadequate ventilation, and the cost of renewal of external protective paints and varnishes and inadequate use of suitable preservative treatments have been the main cause of decline in some uses, especially external wood cladding.

3. Shortage of skilled labour. particularly carpenters, has encouraged the use of building materials requiring less skills such as in-situ and precast concrete. It has also encouraged the use of wood-based sheet materials in replacement of sawnwood.

4. Faster rising prices of sawnwood were observed in most countries, compared with the main structural competitor, cement. For economic reasons, the reduction in cost of panel products competed favourably with sawnwood.

5. Ready availability of wood products in the past has been a prime factor in encouraging high consumption rates in building in countries with a developed wood industry and ample forest resources. In wood-deficient countries, postwar shortages have induced changes to other materials, which for some uses (for example. ground floors) have tended to replace wood permanently. Many developing countries with forest resources have continued exporting their wood but have not been able to develop a local wood industry for internal consumption.

Present status and trends of the forest industries and wood-working industries

FOREST INDUSTRIES

Due to their history of development the forest industries-with the exception of the more modern panel products, in particular fibreboard and particle board industries-are characterized by extreme fragmentation and the prevalence of small units. This mitigates against efficiency and quality in production, as well as ability to invest adequately in research and development. Recent trends in all countries, however, are for rapid concentration and the establishment of larger, better equipped mills. Integration of forest industries. particularly vertically. is helping to eliminate waste and introduce economies of scale.

Recent investment in forest industries in most industrialized countries is adequate to meet immediate requirements. In sawmilling, it was generally directed to improved machining and mechanization of handling and transport to reduce labour, as well as to increased kilning and other measures to improve quality. Better grading to match end uses remains a problem in all producing countries. High quality and greater economy of the product through grading would enhance the competitiveness of sawnwood. The extension and mechanization of the processes of lamination, end and edge jointing and similar improvement processes should lead to substantial improvements in quality of sawnwood for joinery as well as for structural uses.

Panel products have diversified to meet end-use requirements more accurately. and qualities have been improving alongside increased economy in production. In future, a higher proportion of cut-to-size and specially treated or finished boards for specific purposes is likely to be required out of the growing volume of production in all countries.

The greater mechanization of handling and transport of timber introduced in recent years has helped to contain distribution costs through trade channels. The trade itself, complex in structure, is undergoing concentration like the forest industries, and patterns of marketing are changing Growth in size of consumers' in the form of large contracting or manufacturing concerns or purchasing consortia, has resulted in the by passing of trade in a percentage of forest products- particularly board materials of specific qualities and end uses, often in measure of the weakness or inefficiency of the normal distributing trade. In many countries the trade, in addition to performing a collection and distribution function, carries out secondary conversion of materials to suit specific consumer needs. There is also growing integration with the building industry and with components and other material supplies industries.

GROWTH OF WOOD-BASED PANEL PRODUCTS

The decline of sawnwood through substitution by nonwood materials has been to some extent offset, as far as total utilization of forest products is concerned, by the phenomenal growth in the past decade or so of wood-based panel products. Although in turn replacing sawnwood by a smaller quantity of material (but not necessarily of less added value) they have conserved for forest products a greater share in construction than might otherwise have been the case, through:

more complete utilization of logs and residues;

more constant qualities and better ability to match end-use requirements by diversification of products, treatments and finishes, and combination with other materials;

diminishing production costs due to greater possibilities of industrialization of processes;

lower costs of application on site or in factories.

All classes of panel products have grown fast in the past decade, but the expansion of particle board production and consumption has been fastest. Applications of different boards vary greatly between countries, both as regards end uses and the quantities consumed per caput in house building. Structural plywood has grown remarkably fast in North America in particular, and particle board in Europe.

Growth of panel products generally and their use in house construction in particular have been faster than predicted both in Europe and the United States. It is thought that expansion will continue in the 1970s, although at slower rates, particularly in the case of particle board which in the 1960s expanded 3.5 times as fast as GNP. Further technological improvements in production and other factors, however, may once again result in faster growth than is now anticipated.

PROJECTED REQUIREMENTS OF WOOD AND WOOD-BASED PANELS IN THE COMING DECADE

Authorities in many countries foresee a drop in wood consumption per dwelling as a result of the following factors: recent trends in consumption of forest products; the changing pattern of dwellings in most countries to a higher proportion-in some cases a pre dominating proportion-of multidwelling and multi-storey units; and the general decline of traditional craft-based outlets for wood in house building. However, some increase in consumption of panel products per unit is expected. Projections of future demand for all countries and regions are therefore based on continued substitutions of sawnwood by panel products and to an even greater extent by nonwood materials. Nevertheless, although the per caput consumption of sawnwood is expected to fall, the growth in house building is everywhere likely to entail an overall increase in the volume of use of wood and wood-based materials.

Characteristics of overall consumption of wood and wood-based materials in housing are expected to be as follows:

1. In most countries and regions building and housing construction in particular will take a larger share of available wood products, thus increasing the interdependence of the two industries.

2. Consumption of sawnwood is expected to grow everywhere at a slow rate, compared with the growth of housing production generally, in a ratio of 1:5 to 1:3, except in Japan and various developing countries where it may possibly be much higher.

3. Demand for panel products, whose increasing rate of production will decelerate, will grow at a much faster rate than that for sawnwood, and it is estimated that volume of consumption will grow by over 50 percent by the latter half of the 1970s in most countries.

OPPORTUNITIES AND PROSPECTS FOR EXPANSION OF WOOD USES

Assessments of wood requirements in the coming decade are based on the whole on an acceptance of continued rapid decline in quantities of total wood-based material per unit of dwelling, and on an even faster growth of housing requirements, resulting in overall increased volume of consumption. The extent to which estimated requirements will be realized will depend on the ability of the forest products industries to exploit to the full opportunities and possibilities which were already emerging in the 1960s.

Whereas wood products applied in traditional forms will probably lose further ground to competitive materials, they are likely to regain lost ground with greater industrialization of production and new applications. In particular, the following expansions are likely:

1. More prefabricated timber houses in low-rise single-family dwellings (detached, semidetached or in terraces or patio formation), particularly in countries of high building labour costs and where the low-rise market is growing (for example, in many western European countries). The economic level of factory finish will vary between countries depending on the cost structure of their building industries, and production will vary from simple panel structures to fully finished building blocks.

2. A higher wood content can be introduced in conventional low-rise housing by the development of prefabricated components for such items as partitions and external wall panels. Judicious combination with other materials to provide high performance standards will be required, however.

3. A higher wood content might be likely in multidwelling houses if countries will overcome constraints imposed at present by building regulations. Experience in the 1960s in some countries has shown that the highest technical standards can be achieved in sound insulation, spread of flame and fire resistance. Progress will be more readily achieved in most countries in the low- and medium-rise sector.

4. With improvements in quality and increased industrialization in the production of joinery, a bigger share for it in multistorey houses is possible, particularly in regard to external joinery.

5. Wood flooring can regain lost ground by extending the more economical practices (for example, thin hardwood strip on structural wood-based subflooring) which have retained markets in some countries. Suspended ground floors, if economically designed, may also regain some of the position lost to concrete slabs, particularly in low-rise construction.

6. Increasing use of wood and wood products in less industrialized countries is expected as a result of the development of their local wood industries, particularly with regard to seasoning and preservative treatment of secondary species.

All these advances will in turn depend on increased efficiency of the wood-working industries, more technological research, better product design and efficient promotion.

RESEARCH, DEVELOPMENT AND PROMOTION

Since the future ability of the forest industries to maintain and even increase the use of their products in residential construction depends on technological development and better application in product design and manufacture, there is much concern in many countries at the seemingly low level of investment in research and development compared with that for competitive materials.

Similarly, greater promotion efforts, in North America, western Europe and all developing countries are necessary. The level of technical education in the use of wood and wood products was in most countries considered inadequate, particularly in universities and technical colleges. It is clear that more rational utilization of forest products to improve housing production will only be achieved by integrated promotion, which relies on research and technological development as a basis for sound education of the growing generation of designers and builders.

References

(1) UNITED NATIONS. ECONOMIC COMMISSION FOR EUROPE 1968 The housing situation and perspectives for long-term housing requirements in European countries. Geneva. E68.II.E.6.

(2) UNITED NATIONS. ECONOMIC COMMISSION FOR EUROPE. 1968 Major long-term problems of government housing and related policies. Geneva.

(3) UNITED NATIONS. DEPARTMENT OF ECONOMIC AND SOCIAL AFFAIRS. 1970 World economic survey, 1969. New York. E/4841/Add. 1.

(4) ORGANISATION FOR EUROPEAN ECONOMIC CO-OPERATlON.1961 Demographic trends 1956-1976 in western Europe and the United States. Paris.

(5) JAPAN. BUREAU OF STATISTICS. 1969 Statistical handbook of Japan, 1969. Tokyo.

(6) UNITED NATIONS. STATISTICAL OFFICE 1969 Growth of the world's urban and rural population, 1920-2000. New York. E.69.XIII.3.

(7) UNITED NATIONS. STATISTICAL OFFICE. 1968 Compendium of social statistics, 1967. New York. E.67.XVII.9.

(8) UNITED NATIONS CENTRE FOR HOUSING, BUILDING AND PLANNING. 1970 Human settlements and national development: problems and priorities in housing. building and planning. New York.

(9) UNITED NATIONS 1965 World housing conditions and estimated housing requirements. New York.

(10) UNITED NATIONS. ECONOMIC COMMISSION FOR EUROPE. 1967 Management, maintenance and modernization of houses. Geneva.

(11) UNITED KINGDOM. MINISTRY OF HOUSING AND LOCAL GOVERNMENT. 1969 Old houses into new homes. London, HMSO.

(12) NEEDLEMAN, L. 1965 The economics of housing. London, London School of Economics.

(13) UNITED NATIONS. STATISTICAL OFFICE. 1967 Methods of estimating housing needs. New York.

(14) UNITED NATIONS & FAO. 1957 Trends in utilization of wood and its products in housing. Geneva.

(15) UNITED NATIONS & FAO. 1964 European timber trends and prospects: a new appraisal 1950-1975. Geneva.

(16) HOUSING IN JAPAN, BY HIRAGA AND FURUKAWA. DOCUMENT. 1966 Towards Industrialised Building: Proceedings of 3rd CIB Congress, Copenhagen, 1965. Amsterdam, Elsevier.

(17) STONE, P.A. 1959 The economics of housing and urban development. London, HMSO. (Building Research Station, Garston)

(18) UNITED KINGDOM. MINISTRY OF HOUSING AND LOCAL GOVERNMENT. 1952 The density of residential areas. London, HMSO.

(19) STANFORD RESEARCH INSTITUTE. 1954 Americas demand for wood 1929-1975 Stanford, California

(20) UNITED NATIONS. COMMITTEE ON HOUSING, BUILDING AND PLANNING. 1970 Social implications of high density housing. New York. ESA/HBP/AC1/2.

(21) UNITED NATIONS. BUREAU OF SOCIAL AFFAIRS. 1966 World population prospects New York. E.66.XIII 2.

(22) U.S. FOREST SERVICE. 1965 Timber trends in the United State. Washington, D.C.

(23) UNITED NATIONS. ECONOMIC COMMISSION FOR EUROPE. 1968 Annual bulletin of housing and building statistics for Europe, 1967. Geneva.

Report of the consultation

1. The Consultation recognized that the current housing situation, particularly in the developing countries, could be described as serious and urgent, with world population rising at an annual rate of 2.2 percent. High population growth rate, with an even faster increase in population in the low-income groups, an ever-increasing number of squatters in the large cities, the absence of basic community facilities, and large-sized households crowded in small housing units, continued to characterize the housing situation in the three continents of Africa, Asia and Latin America. Housing conditions in most of the urban areas of the developing world had reached critical limits.

2. The housing deficit in the past had accumulated mainly in the low-income groups, and present trends indicated that this would continue. Spiralling land prices, the increasing pressure on urban land, lack of finance, high building costs, and continuous shortage of building materials were all contributing factors to the widening gap between the demand and supply of houses. The full implications of the present rate of urban growth, and the gravity of the problem of housing for an urban population that is expected to nearly double in the next 20 years, had not yet been fully realized. On the basis of several assumptions with regard to average annual population increase, average household size and number of households per dwelling, during the next 30 years an average annual output of 25 million dwellings-or five dwelling units per thousand inhabitants-should be constructed just to provide for natural increase of population. The present rate of construction in most developing countries has hardly exceeded two per thousand inhabitants, particularly in the more populous ones. This disproportion between present house-building activity and requirements is already a broad indication of the rate of deterioration in housing conditions in the developing countries.

3. Against an indicative annual production target of ten units per thousand inhabitants suggested by the United Nations for the first Development Decade of the 1960s, the actual achievement in the case of the developing countries has been in the order of only two to three units per thousand. The developed countries, as might be expected, have fared much better, and some of them have exceeded this target. Even this apparently high target of ten units per thousand inhabitants, if fulfilled, could wipe out the existing shortage only in the course of the next 30 years, in addition to catering for the increase in population.

4. The Consultation agreed that housing needs could be classified under the following four main categories:

(a) the need resulting from the net addition to population, due to natural increase and migration;
(b) the need arising from replacement of dwellings in the housing stock due to obsolescence;
(c) the backlog in housing, consisting of people inadequately housed or without houses of any kind at the present time;
(d) disaster housing, which takes into account housing for the resettlement of people displaced by floods, earthquakes, landslides and other disasters.

5. One of the critical variables affecting the estimates of housing needs resulting from population increase relates to the number and size of households, and this is illustrated by the case of Japan. According to the 1965 census the population increase of 10.17 percent during the 1955-65 period was accompanied by an increase of 34 percent in separate households. This element has a very important bearing on the estimation of housing needs, particularly in the case of the developed countries.

6. The Consultation noted Table 2, which gives world population growth from 1920. The figures relating to the increase in urban population of the developing countries called for special attention as they had grave implications in terms of urban housing requirements. It was noted that the urban population of the developing world would increase from 720 to 2 080 million (a threefold increase) in the 1970-2000 period, while in the case of the developed countries there was an expected increase of 400 million (or 66 percent).

7. Apart from the growing shortage of housing in the developing countries, due to the widening gap between population increase and rate of construction, the conditions of the existing stock were considered to be far from satisfactory. The obsolescent stock in Africa is said to be 36.3 percent, in Asia 40 percent, and in Latin America 33.3 percent of the total stock. Due to the paucity of resources, efforts have necessarily to be directed toward improvement of existing unfit dwellings rather than attempting their wholesale replacement. Even in the case of the developed countries, replacement requirements are high: the figure for Europe is 33 to 50 percent for the period 1961-80, while it is 25 percent for the period 1967-77 in the United States and 40 percent for the period !965-85 in Japan.

8. Moving from estimates of needs to the prospect of meeting them, the Consultation fully understood that the estimate of needs, however accurately established, gave no indication of what was likely to be actually achieved in the future. This would depend on the adequacy of resources and the ability or the building industry to meet the demand. Tables 4 and 5 gave investment in ho-using as a percentage of the GNP in both developed and developing countries. While in most of the developing countries it is in the order of 2 to 3 percent of GNP, the developed countries were devoting 5 to 6 percent of their GNP to investment in housing, this figure rising even to 7 percent in countries like Switzerland. Considering the fact that the base of the GNP is very small in the ease of the developing countries, real investment in housing was considered quite inadequate compared with needs.

9. The trends in the types of houses that are likely to be built in the future will in turn determine the kind of building materials, including wood, that will go into these buildings. The Consultation expressed the view that while rural areas have not so far witnessed any significant change in the types and methods of construction, the trend in respect of urban housing in both developing and developed countries was toward multistoried construction, the proportion of multistoried units to total units varying from country to country. It noted that the decline in the use of wood-based products, particularly in terms of consumption per unit, could be partly attributed to this trend toward high-rise buildings. Regarding the size of dwellings, the steady increase in space standards in the developed countries resulting from the continued expansion of personal incomes could be expected to continue. On the other hand, economic limitations have restricted the size of dwellings in the developing countries. It was indicated that the median area per person in Hong Kong was only 43 square feet and it seemed that prospects for increase in floor area in the developing countries as a whole, now around 10 square metres (107 square feet), were not bright.

10. The Consultation considered the implications of these trends for the timber industry. In the case of single-family houses,-timber-frame houses now account for 88 percent in the United States, 90 percent in Canada, and 98 percent in Japan, but with the increasing trend toward multistoried constructions the use of timber for structural purposes was likely to decline. Contrary to what might be expected, timber-frame houses meet with only limited acceptance in many countries of the developing world, even in those which have rich forest resources. This is attributed to the lack of prestige of " wood-housing" in these countries. If no solutions are found to this problem it will further contribute to the decline in the use of timber in these areas.

11. The Consultation agreed that there were two distinct trends in the use of building materials: one, importance would continue to be attached to the use of traditional and local materials like wood in the construction of small houses; and two, there would be an increasing use of materials like cement and steel in multistoried dwellings and high-rise construction. With some exceptions, even in the low-rise sector, it was mostly in the forest-rich developed countries that a large proportion of small houses had timber load-bearing walls. In most European countries, as well as in developing countries, masonry was still the important wall material. In both developed and developing countries, in the case of multistoried dwellings, reinforced concrete, in-situ or precast, was the main material for construction. The decline of wood for structural purposes was also accompanied by a substantial fall in its use for external finishes and flooring, and only in joinery has wood continued to maintain its position against substitute materials.

12. The Consultation noted that despite the general trend toward multistorey housing, a new trend was now apparent in certain countries in Europe toward single-family housing. Multistorey housing can combine with advantage the use of a heavy structure with other lightweight elements. There was a need to introduce an element of flexibility in urban development. Consideration should therefore be given to short-life housing. It was pointed out that the replacement of structures was more often due to changes in land use, economic returns and a demand for higher standards of living rather than to physical obsolescence.

13. Concern was expressed over the fact that many developing countries with forest resources have continued to export their wood but have not been able to develop a local wood industry for internal consumption. Such countries needed to be helped to develop a local wood industry.

14. The Consultation observed a common deficiency in the-planning for production of building materials in the developing countries. In most cases there was no evidence to suggest that the production of building materials was planned according to the demand for building and construction activities. No serious attempt seemed to be made in most development plans to make demand and supply projections of building materials in accordance with projections for total economic growth. It was noted that developing countries have often made efforts to augment the supply of key materials such as cement and steel, but that this exclusive and obsessive attention paid to the key industries had led to the neglect of locally available traditional materials such as bricks, second-quality timber and wood products. Not only should detailed studies of the input structure of the building and construction industry be undertaken but, in the case of materials like wood, which have alternative uses, the demands emanating from all sectors have to be summed up to arrive at total requirements. It was stressed that this is an important exercise which the developing countries will have to undertake if they are to plan for self-sufficiency in respect of building materials.

15. considered that both industry and trade in forest products were undergoing a profound structural change as a result of larger and better equipped mills taking the place of a large variety of small units. It was agreed that vertical integration of the forest industry, and on the trade side the establishment of a direct link between manufacturers and large-scale consumers, were positive trends for the reduction of distribution costs.

16. Summing up, it appeared from estimates made that even although the consumption of wood per housing unit was likely to decrease, the total volume of demand would continue to rise, in view of the rapid growth of the building industry to meet the growing needs of development. However, this increase in demand would depend on the increasing efficiency of the woodworking industry and its ability to face competition from substitute materials; in this respect, research, development and promotion would have to play an important role.

17. There appeared to be a need in developing countries for more research on life expectancy of houses and the economic advantages of long-life buildings as opposed to short-life constructions requiring minimal capital investment.

18. Based on the above considerations the Consultation recommended that:

(a) Developing countries with forest resources should promote local secondary wood industries for domestic consumption and seek such bilateral and international assistance as may be necessary for this purpose.

(b) Developing countries with short supply of forest resources should promote the most efficient and selective use of imported wood in their housing construction programmes.

(c) In the formulation of development plans, governments should pay increasing attention to the supply of building materials in general and wood-based materials in particular, as a basic measure for the implementation of their national housing programmes.

(d) In view of the advantages to be derived from the use of wood in housing construction, the woodworking industry should increase its efficiency and improve the quality and performance of wood-based materials in order to supply a growing housing market and compete favourably with other building materials.

(e) In establishing national housing programmes, governments should consider the economic advantage of short-life (as well as permanent) lightweight wood construction that may readily be replaced totally or partially. Such a policy would inject an element of flexibility in urban and rural development and permit the timely adoption of higher standards of living for the population.

(f) Social and economic studies should be undertaken to determine requirements which would lead to the most suitable low-cost housing designs using wood.

(g) In view of the higher demand for urban housing, governments should study the possibility of using wood-based infillings in high-rise structures and wood-based materials combined with other materials for low-rise high-density housing, with proper technical provisions for life safety.

(h) Governments should pay maximum attention to squatter settlements in and around cities and take appropriate measures to solve this problem.