O.H. KOENIGSBERGER
PROFESSOR O.H. KOENIGSBERGER IS head of the Department of Development and Tropical Studies, Architectural Association School of Architecture, London, United Kingdom. This paper was prepared in collaboration with the Forest Industries and Trade Division of the FAO Forestry Department from the background papers listed at the end. Grateful acknowledgement is made to their authors. Special acknowledgement is also made to the Swedish International Development Authority (SIDA), whose financial support made possible field work by three architects specializing in problems of the use of wood in housing in developing countries. Their work as FAO Trust Fund Experts in Africa, Asia and the Far East and Latin America resulted, among other things, in the three regional reviews on the use of wood in housing in the developing countries and the supporting country reviews which have been contributed as special papers to the Consultation. They are listed at the end of this paper.
THE TASK OF THIS PAPER is to identify the factors influencing the choice of wood products as building materials, to review trends and consider means to increase the utilization of wood in low-cost housing in developing countries. Thus, the subject matter touches that of all other sections, except that it refers specifically to the developing countries. The present paper therefore does not attempt to go into detail on all the points that come within its scope; many of these have been fully covered in other sections.
In identifying the factors influencing the use of wood in housing the paper discusses climate-important in developing countries, since most of them are located within the tropics; social factors and the pressures resulting from the high rate of urbanization which often lead to wood being regarded as a "poor man's material"; supply of timber products, with particular reference to the inadequate development of forest industries; economic factors and the effect of low levels of income; and finally technical factors, which can differ considerably from those prevailing in the developed countries of the temperate zones.
Having identified these factors, the paper sums up the positive and negative aspects and from these derives a picture of present trends. It then suggests courses of action to be taken by national governments and international organizations to increase the use of wood in housing.
The enormous housing needs of the developing world must be viewed both quantitatively and qualitatively.
Quantitatively, one must consider the large disproportion between the number of households and the number of housing units available. This disproportion produces results ranging from overcrowding to complete lack of shelter. Qualitatively one must recognize the very low prevailing standard of dwellings, which often lack the most rudimentary basic necessities.
These shortcomings continue to be aggravated by the high prevailing population growth rate, by migration from rural to urban areas, and by the need to replace large parts of existing housing as a result of dilapidation and natural disasters. Typical population growth rates in developing countries are 2 to 3 percent annually, which means that the population doubles within some 25 to 30 years. Many big cities, however, grow at more than twice this speed and double their population every 10 years, or even less. Moreover, the most rapid population growth rates occur in the uncontrolled urban settlements of metropolitan fringe areas, which generally double their population in a mere five to seven years. If present trends continue unchecked, developing countries will have increasingly to face problems of shanty towns, bidon-villes, favelas, barriadas or by whatever names they are called (1).1
(¹The world's housing situation is described comprehensively in Section 1. This present paper therefore confines itself to some of the more pertinent aspects in developing countries.)
According to the method of estimating housing needs suggested by the United Nations Centre for Housing, Building and Planning (2) the world's requirements for housing could be met if ten dwelling units were provided annually for every thousand inhabitants. It is possible to form an approximate idea of the magnitude of the housing need on the basis of this formula if it is realized that in developing countries the annual average number of new dwellings officially recorded was only two to three units per thousand population during the last decade.2 This number is not enough to cater for even half the population increase, let alone to alleviate the existing deficit or to meet the growing demands of migrational population or the replacement of obsolete housing stock. In other words, to meet their needs developing countries should have built 27 million units per year, that is about 3.4 times the actual output of 8 million units per year over the past 10 years.
(2 In industrialized countries, the estimated average annual rate of construction was about 7.5 dwellings per thousand population during the same period.)
It must be understood, however, that the officially recorded figures for house construction do not include "spontaneous" dwellings, built mainly in rural areas without some kind of municipal control, or the growing number of unauthorized makeshift shelters in the uncontrolled settlements of urban areas. In spite of the gravity of the situation outlined, most people meet their housing need through their own efforts without economic or technical assistance and erect rudimentary shelters utilizing traditional, unsophisticated techniques and readily available materials (22).
THE SHARE OF WOOD IN HOUSE CONSTRUCTION
In order to give a rough idea of what annual quantities of wood are presently utilized or could be utilized in house construction in developing countries it may be assumed-with the risk of overgeneralization-that any amount between 0.5 and 6 cubic metres of final wood product per dwelling unit would be a justifiable estimate. This spans the extremes from a mainly non-wood house with only roof structure, doors and windows made of wood to an all-timber low-cost house.3 Obviously, the actual average wood quantities within this range will depend on local conditions, as outlined later in this paper, and may vary widely from region to region.
(3 Even in wood-deficit regions the spanning of large openings requires a minimum of timber, such as poles, particularly when roof dockings tend to be heavy as in hot-arid regions and where door and window shutters, though scarce, are important. The figure for all-timber houses has been taken from the example of Malaysia's FLDA housing scheme which uses 6 cubic metres per unit of 45 square metres of floor area. The very low quantity of 0.5 cubic metre for only the roof structure of the same house has been taken as the minimum consumption per house. An FAO study on low-cost industrialized wood housing in Honduras estimated the required timber quantity at 4 cubic metres per 36 square metres floor area.)
Table 1 shows estimates of the present annual consumption of wood for housing and of the annual consumption that would be required if total housing needs of developing countries are to be met. It can be seen from the table that at present about 8 cubic metres of wood per thousand inhabitants are used annually; in fact, the actual consumption is higher in view of the large number of unrecorded constructions. It is evident that the potential for wood consumption for housing in developing countries is more than double present consumption.
One of the fundamental objectives of housing is to provide protection from the elements. In addition to protection from rain and wind in the tropics it is particularly important to maintain an environment of acceptable temperature and humidity. Also, in certain parts of the world housing must be able to withstand earthquakes and hurricanes.
Almost all the developing countries are found within the tropics. Thus, for the purpose of studying the influence of climate, the following broad zones are considered: warm-humid, hot-dry, and composite. The specific requirements of earthquake and hurricane zones are considered separately.
TABLE 1. - ESTIMATED ANNUAL CONSUMPTION OF WOOD IN HOUSING IN DEVELOPING COUNTRIES PER THOUSAND INHABITANTS
|
|
Number of units |
Wood consumption |
|
|
Range |
Midrange value |
||
|
Cubic metres |
|||
|
Housing output over the last decade (officially recorded) |
2.5 |
1.25 to 15.00 |
8.13 |
|
Target to meet total housing needs |
10.0 |
5.00 to 60.00 |
32.50 |
ASSUMPTION: 0.5 to 6 cubic metres of final wood product per housing unit.
WARM-HUMID CLIMATES
Warm-humid climates are found within the range of 15ø north to 15ø south. They are characterized by high humidity and generally high air temperatures with little diurnal or annual variation. Precipitation is generally high, at times exceptionally high. Winds are generally light but can become strong during rain squalls. Brightness of the sky can be intense and sky glare caused by diffuse radiation from the frequent cloud cover can be painful.
In such climates constructional characteristics must include large apertures to facilitate the air movement needed for relief from heat and humidity and roof overhangs to shade exterior walls from solar radiation. Thermal characteristics of the building material must show high resistance to heat flow and low thermal capacity in order to avoid heat storage and consequent reradiation during the night.
Wood meets these requirements ideally. Its physical properties allow its use for spanning the large openings that permit maximum air movement and providing the framework required for overhanging roofs. Its low density, and its internal structure which traps air in its cells after seasoning, give it a high thermal resistance and low thermal capacity. Also, large quantities of wood are available in the hot-humid zones, which are estimated to contain three fifths of the world's timber resources. It is hardly surprising that building traditions in these climates are often based on all-wood construction.
All-timber housing traditions in warm-humid climates
Many warm-humid areas, such as the Malabar coast of India and parts of China and Japan, have well-established traditions of all-timber housing. These houses are mainly rural. Design and construction have been shaped by craft traditions which go beyond the utilitarian. Elaborate carving and elegant detailing are part of the design. House size varies according to the wealth of the owner, but decorative woodwork is not exclusive to any one income group. There are examples of temples, palaces and very humble rural homes all in wood and all of a high standard of craftsmanship.
A typical rural all-timber house in, for example, Malaysia, would be formed from substantial wood or bamboo framing with columns supported on stone pads (in some countries wooden piles are used as foundations) supporting a raised floor, clear of the ground as a protection against floods or animals. The frame joints are morticed and notched without the use of nails or any metal fasteners, and the spaces between frames are filled with panels made of boards fixed to fillets. Internal partitions are made of wooden panels or woven grass. Large openings protected by carved wooden grills or lattice-work take full advantage of the breeze and are protected from rain and sun by wide overhangs. The roofs are basically simple, but ridge ventilators, highly decorative ridge covers and cave boards create a feeling of wealth and variety of form. Roofs are always pitched and covered with reed or leaf thatch on all-wood substructures. In some countries bamboo or wood shingles, various sheet materials or even glazed tiles are used as waterproof covering.
All-wood construction is a natural form for warm-humid countries and has become established as a rural tradition.
Traditions of mixed construction in warm-humid climates
Houses of mixed construction are common in urban and suburban areas of the warm-humid tropics. Urban trade and industrialization have brought to the cities of the developing countries new materials that are claimed to be more appropriate to modern urban life. Walls of burnt bricks or cement blocks require less sophisticated craftsmanship than timber walls and are considered more durable. Roofs of clay tiles, asbestos, cement or metal offer less protection from heat than thatch or shingles, but they are easier to build, cost less to maintain and are less flammable. Durability and ease of maintenance appeal to the urban investor.
HOT-DRY CLIMATES
Hot-dry climates occur mainly in two belts, at latitudes between approximately 15ø and 30ø north and south of the equator. There are two marked seasons-a hot summer and a somewhat cooler winter. The temperature rises quickly after sunrise to a maximum which is high even during the cool period. At night it is cold, and during the cool season very cold. Humidity is generally low and precipitation is negligible. The sky is normally very clear and solar radiation is direct and strong. The absence of cloud permits easy release of stored heat in the form of long-wave radiation. Where such climates border on the sea (maritime desert climate) diurnal variation is somewhat less, humidity is steadily high and solar radiation has a higher diffuse component.
Dense materials such as stone or brick are best suited to these climates, since they have the capacity to store considerable amounts of heat before they begin to emit it by reradiation. This time lag can be exploited and used to direct the heat of the day to counteract the coolness of the night.
Apart from being a scarce material in these climates, wood shows the opposite thermal characteristics. As mentioned, it has high resistance to heat flow but low thermal capacity. Thus, its use is limited to spanning openings for doors and windows and for forming roof substructures. Its thermal characteristics can be put to advantage by using it for shading devices and window shutters, but there is not much scope for extending its applications. The increase in the manufacture of processed wood products may, however, lead to a wider use of timber components within the limited range of applications.
COMPOSITE CLIMATES
Composite climates include two types-the monsoon and the tropical upland climates.
Monsoon climates are sufficiently far from the equator to experience marked seasonal changes in solar radiation and wind direction. Three seasons occur normally. In the hot-dry season, which covers approximately two thirds of the year, temperatures are very high in daytime and cooler in the evenings, with a great diurnal range. There is no rain during this season. In the warn-humid period, humidity rises to very high levels. Precipitation is heavy during the monsoon period. Sky conditions and solar radiation vary markedly with the seasons. Winds are hot and dusty during the dry period and fairly strong and steady during the monsoon.
Tropical upland climates occur on mountain ranges and plateaus more than 900 to 1200 metres above sea level. Seasonal variations are small near the equator, but further away they follow those of the nearby lowland. Temperatures are characterized by large diurnal ranges. It never becomes extremely hot but can be quite cold. Humidity is varied, but high. The same is true for precipitation. Rain often falls in heavy concentrated showers. Solar radiation, especially ultraviolet, is strong during the clear sky periods.
Traditional use of timber in composite climate zones
Some of the largest and oldest urban settlements have developed in the great river valleys of the composite climate belt. The cities of the Indus, Ganges and Brahmaputra valleys, the Nile valley and Mesopotamia are among the best-known examples. Except for comparatively short periods of monsoon rains or river floods, these are essentially dry areas with sparse natural timber resources. High concentrations of population have been maintained for many centuries through intensive cultivation of irrigated land.
The meagre timber resources that used to exist in the valleys and in adjoining hills have long been exhausted through clearance for agriculture and extraction of fuel and building timber. The inhabitants have learnt to think of wood just like the people of the desert lands. For both, wood has become a precious material, brought from far-away forests to be used sparingly for those parts of their houses that cannot be fashioned from the more readily available inorganic materials. The cities of the composite climates of the tropics have traditions of using timber with consummate skill, but never in large quantities.
The tropical uplands are characterized by smaller concentrations of population and larger forest reserves including, in the higher reaches, substantial stands of softwood. The fact that some of the mountain forests were almost inaccessible acted as a safeguard against depletion through overextraction. It is in tropical upland cities like Srinagar and Katmandu that a few traditional examples of urban timber houses and palaces are found.
WOODEN STRUCTURES IN EARTHQUAKE AND HURRICANE AREAS 4
(4 These are described in some detail in Section 4, Part I.)
A number of developing countries fall within the earthquake zones of the world. They include parts of Pakistan, India. Iran, Indonesia, the Philippines, some of the South and Central American countries and parts of east Africa.
Timber, as a light material of high tensile strength, has always been a useful material in earthquake zones. The elements of a timber building can be joined effectively and form structures of great rigidity that will withstand horizontal as well as vertical loads. Japan is a notable example of a country that, in the course of centuries, has developed the craft of making superb timber houses which have assisted the populations of their cities to survive severe earthquakes. These experiences are reflected in the Japanese building codes which rank timber- and steel-framed structures as superior to buildings in brick, stone or concrete block masonry.
The experience that many timber houses were destroyed in fires that broke out after earthquakes has, in some cities, led to a preference for reinforced concrete specially designed to withstand the horizontal stresses that occur in earthquakes. This is understandable, but a more farsighted reaction would have been to investigate and remove the causes of post-earthquake fires, particularly vulnerable gas mains and faulty cooking and heating appliances. It is significant in this context that international teams of experts chose premanufactured timber houses for the resettlement of the thousands of families rendered homeless by recent earthquakes in Yugoslavia, Turkey and Chile.
In countries subject to hurricanes and tornadoes, as in earthquake areas, timber construction has the advantage of the comparative ease of handling joints. High winds subject the walls and roof of a building to both positive and negative pressures. Roof deckings, overhangs and other projections are particularly vulnerable. The use of timber as the main structural material makes it possible to tie all parts of a house firmly together and anchor the whole safely to the ground. Some hurricane regions, such as Florida, have special by-laws to enforce this practice (3).
It is not enough to assume that an earthquake-resistant building will also withstand hurricanes or tornadoes, although records show this to be sometimes the case. In regions where both occur, timber buildings can be easily designed to withstand both (4).
In the rural areas of the warm-humid zones, where wood and other organic materials are plentiful and readily available, the suitability of these materials for housing construction is traditionally established. Their use is also justified on grounds of climate control. Wood is extracted, processed and used by the rural population as and when required. Building timber houses is a routine activity requiring skills that are available in the village community. The repair and maintenance of these houses generally formed part of the annual cycle of rural tasks and were totally integrated into the rural pattern of life (5).
In areas where timber is less readily available, such as the hot-dry zones, wood is used in combination with other materials and only for functions for which no other local material will do, such as roof beams and trusses and lintels over large openings. Craftsmanship in wood is regarded as a speciality and does not form part of the recurring pattern of rural life (6).
LIVING PATTERNS AND STATUS PROBLEMS IN RURAL AREAS
The functions of a peasant's house in the tropics are generally limited to those of an emergency shelter and a safe storage place for the owner's possessions; because of the climate it is possible for most other activities to take place out of doors. There is one function, however, which is not affected by the climate. This is the need to express the owner's position in society. This can be done either by size or decoration. In most cases the owner's status is clearly expressed in spatial terms; the house of a chief in a village is unmistakable because of the size of buildings, storage bins and compound. In others, the elaborate decorations of certain elements help to establish the importance of the owner. Where there is a tradition for building in timber, as in Malaysia or Thailand, dignitaries' houses have richly decorated timber elements and elaborate traditional carvings which convey to the community a great deal about the owner.
In many cases the preference by a colonial administrator for imported foreign materials has established these as more desirable and they have become an overriding status symbol. This has led to the use of inorganic materials in village housing This process is not easily reversible, except where national feelings seek expression in the revival of traditional forms, including the use of local materials, particularly timber.
LIVING PATTERNS AND STATUS PROBLEMS IN URBAN AREAS
Few of the age-old customs of rural communities survive the transfer to the urban scene. The pattern of life in the cities is more likely to be regulated by administrative measures than in smaller communities where behaviour is governed by tradition. High urban land values impose a high density of housing, and the physical separation of houses from one another is becoming less and less feasible. There is a trend toward multistorey dwellings near city centres.
People migrating in large numbers from rural areas to cities create problems of accommodation and absorption. They have to live in overcrowded, temporary accommodation, often in badly built wooden hovels on valuable sites very near city centres. The social unacceptability of this unsettled section of the population adds further to the prejudice against the material from which their huts are built, mainly wood of inferior quality. Housing of predominantly wood construction in any urban setting is believed to have an inherent fire risk. This contributes to an unfounded prejudice against the extensive use of wood. Legislative measures prompted by fear and enacted hurriedly in the face of this situation set up restrictions that tend to discourage its use.
The sophistication of city life and the exposure to new fashions, materials and types of construction undermine traditional building methods. Wood finds itself in competition with a wide range of building materials available on the urban market. Parts of the building fabric hitherto constructed in wood are supplanted by other materials alleged to be more practical to use, or more consistent with the pattern of urban life. Urban buildings require a wider variety of skills and greater specialization. The construction of houses is considered an operation outside the normal competence of the ordinary citizen; a task for the specialist.
Only a few cities in developing countries have well-established traditions of urban housing. These include the cities of north Africa, Rajasthan, the mogul cities of northwest India and Pakistan and cities in northern Nigeria, Iran and China. They are all situated in arid climates where organic materials are scarce. Houses are mainly constructed in stone or brick with wooden roof beams, windows and doors.
Most of the cities that have grown up in the more humid regions of the developing countries are comparatively young and have not developed a distinctive town house style. Though wood and other organic materials for building are readily available in the surrounding countryside, an extensive use of wood for the construction of town houses has not become established.
Organic materials have tended to become the exception in the town houses of the well-to-do. They have remained the poor man's choice and the sole resort of newcomers from rural areas. Unable to afford the expensive manufactured materials, which are often imported, the newcomers employed their rural skills and used whatever materials came to hand. Not being owners of urban land they had no choice but to erect temporary and inadequate huts on public or privately owned open spaces, as near city centres as possible, sharp and inescapable reminders of social and economic inequalities.
All this helped to convince the urban middle classes of the importance of durable and permanent houses as the basis of their relative position in urban society. Steel windows, concrete columns and sheet-iron or asbestos roofs came to indicate an owner of property of lasting value and sophistication.
TIMBER RESOURCES
Many developing countries are rich in natural forest resources. These consist predominantly of broad-leaved trees and cover a considerable part of the available land. Section 2 deals with this at some length and from it are summarized in Table 2 the forest resources of the developing countries and their recorded annual removal.
It can be seen from the table that out of a total removal of 185 million cubic metres of industrial wood in developing countries, 123 million were in the categories suitable for mechanical wood processing industries (sawmilling, wood-based panel production). The net export from developing countries amounted to 32 million cubic metres of roundwood equivalent, which means 93 million cubic metres of roundwood remained for processing and use on the domestic market. It should be kept in mind that the above figures do not include a considerable amount of unrecorded removals which increase substantially the amount of wood available for consumption.
TABLE 2.- GROWING STOCK AND ANNUAL REMOVAL IN DEVELOPING COUNTRIES
|
|
Growing stock¹ |
Industrial wood removals recorded in 19682 |
||
|
Total |
Coniferous |
Nonconiferous |
||
|
Million cubic metres |
||||
|
DEVELOPING REGIONS |
||||
|
Africa 3 |
34 900 |
300 |
34 600 |
344 (16) |
|
Asia and Pacific 5 |
40 900 |
6 000 |
34 900 |
107 (73) |
|
Latin America |
122 900 |
2 800 |
120 700 |
44 (36) |
|
TOTAL DEVELOPING REGIONS |
200 900 |
9 100 |
191 800 |
185 (123) |
|
DEVELOPED REGIONS |
156 600 |
115 400 |
41 200 |
1 012 (601) |
|
WORLD TOTAL |
357 500 |
124 500 |
233 000 |
1 197 (724) |
1Figures adapted from FAO, World forestry inventory 1963. - ² From FAO, Yearbook of forest products 1969-70.- 3 Excluding South Africa.- 4 Figures in brackets indicate volumes used for mechanical processing.- 5 Excluding Australia, Israel, Japan and New Zealand, but including China.
It is estimated that 60 to 70 percent of the 93 million cubic metres went into the building sector, which built an annual average of 8 million recorded new dwelling units, a considerable quantity of nonresidential construction, and also a large number of unrecorded shelters, over the last decade. Large amounts of wood also went into repairs' alterations and improvements of existing dwellings and constructions.
A glance at the table and comparison between industrial wood removals and growing stock show that the forests could contribute many times more than they do today. Obviously comparisons can only be made with qualifications, due to limiting factors such as inaccessibility of large forest areas, marketability of only a limited proportion of the species, general underdevelopment of forest industries, etc. Nevertheless, it seems safe to state that even if the building sector increases its annual output of new dwellings threefold or fourfold to meet housing requirements, the wood potential of the forests will be sufficient for decades to come, presupposing sound management.
Apart from the natural forests, man-made plantations of quick-growing exotic conifers could be a potential source of raw material in the tropics. The success of their establishment has been demonstrated in many countries. The fast growth and short rotations of these exotics, and their suitability for fibreboard and particle board manufacture, could greatly improve the supply of building materials in developing countries. In east Africa, where exotics have been grown for over 30 years, lumber products from plantation trees are already providing material for the housing industry. However, problems resulting from their properties have to be solved.
SUPPLY OF TIMBER PRODUCTS
Extraction
A large proportion of tropical forests are at present unproductive in that they are physically or economically inaccessible. Production of forest products presupposes the provision of road and extraction infrastructure and installation of local processing plants within the framework of a well-considered and declared forest policy for the fullest utilization of the available resources.
In spite of the seeming abundance of species, production is low due to the historic pattern of log export, which concentrates logging, extraction and conversion on selected species. This selective felling results in low yields per hectare. Expenditure on the construction of extraction roads, often very high, is thus distributed as overheads over only a few trees felled. This could be spread over other species (with equally noteworthy physical and mechanical properties) not currently in demand on the export market-the lesser known or so-called secondary species. Thus less selective felling and extraction will lead to the removal of greater volumes, with consequent lowering of production costs and better utilization of resources. From the supply point of view, this will make more timber available on the local market to meet the needs of the building industry. Timber export is desirable in that it brings needed foreign exchange for the purchase of machinery and equipment. But sole dependence on this without the parallel development of the local market often leads to inefficient forest management, maintains the cost of the resulting product high and starves the domestic market of timber, albeit not of the primary species.
Processing
The existence of large forest areas in a developing country is not in itself enough to guarantee the availability of wood as a construction material. Such availability must also depend on the installation of processing plants. In almost all developing countries this involves the outlay of capital with a large foreign exchange component, especially for panel production. Running costs for fuel, lubricants, transport, and so on, are also contingent on foreign exchange. Mechanized sawmilling is replacing rudimentary pit-sawing, and most developing countries now have sawmills for primary conversion. However, many are obsolete and inefficiently run, and modernization and improvements are necessary.
Local processing will result in export products of higher value, and the processing of lesser known species would provide a local supply of wood products for construction. Malaysia is an example of a country where the export of logs was prohibited for a period, and forest policy encouraged the felling and removal of any usable timber for local conversion. This led to abundant supplies of cheaper timber being regularly available, especially in the lower grades, which encouraged timber house construction (11).
DISTRIBUTION AND MARKETING5
(5 This subject is dealt with in some detail in Section 2.)
The distribution of processed wood materials has been for some time in the hands of wholesalers and retailers, resulting in the growth of a marketing structure. The essential aim of processing and marketing activities should be to make available a steady and continuous supply from as wide a variety of species as possible, in various sizes, well seasoned, graded to ensure uniformity, and treated with preservatives where inherent natural durability does not exist.
Marketing should also involve promotion. This is particularly important in the introduction of the lesser known species. Research has contributed to knowledge on the identification of species, their physical and mechanical properties, and the use to which they can be put. Where lesser known species have properties comparable with those already established, promotion directed at the ultimate consumer can do much to gain their acceptance as substitutes.
HOUSING COSTS AND THE CHOICE OF MATERIALS
With the data available it is not possible to make statements of general validity about housing costs and the way they are affected by the choice of materials. Costs of materials and labour differ considerably from country to country. Furthermore, in considering timber as a building material, one must bear in mind that current costs in developing countries can be greatly improved through rationalization of supply aspects.
General cost comparisons are best made element by element, and restricted to warm-humid countries where timber is suited to the climate and relatively easily obtainable. Most lower income builders are pragmatists, and decide on the material for each element on grounds of cost, availability and durability, ending up with a composite house.
Foundations. The precast concrete pads for the uprights or stilts of a wooden structure are usually cheaper than the strip foundations for a masonry wall.
Walls. Brick or block walls are generally cheaper than timber post and beam structures with cladding. This cost advantage outweighs in most cases the higher foundation costs.
Roofs. Small houses in warm-humid countries with high rainfall require pitched roofs. Timber beams, rafters, purlins and battens for sheet- or tile-covered roofs are almost always cheaper than roof structures of concrete or steel.
Doors and windows. Wherever door and window dimensions are standardized, mass-produced timber joinery is cheaper than steel or aluminium windows or concrete door frames.
Floor beams and floors. In two-storeyed buildings the individual builder normally finds wooden beams and floor planking the cheapest solution. However, in large projects precast concrete units may prove cheaper.
Various attempts have been made to quantify costs in all-timber or part-timber houses. At the University of Kumasi, Ghana, J.P.R. Falconer has carried out experimental and prototype timber construction for middle-income people. He has published comparative figures demonstrating that they were cheaper than composite housing. He gives costs of $54 per square metre and claims that these costs could be further reduced by the mass manufacture of timber components for a large number of units. By contrast, agency-built housing in Ghana costs from $65 to $75 per square metre utilizing concrete construction (7).
In 1970 a feasibility study of prefabricated wooden house production was carried out by a French corporation for the Cameroon Ministry of Development (19). The study was aimed at setting up a pilot factory which would produce 400 units a year after the third year of operation. The basic house design, with a floor area of 90 square metres and consisting of three bedrooms, a living room, kitchen and bathroom, was costed both as an all-wood construction and as a concrete wall construction. The all-wood version turned out to be 17 percent cheaper. (Total cost, including optional extras such as sanitation, electricity, interior painting, guttering, etc., was $4 800 or $53 per square metre for the timber house and $5 800 or $64 per square metre for the masonry house.) The house design itself could not really be considered a low-cost unit whatever material was used. However, the message is there: a feasibility study, which considered timber supply aspects as an essential part of the equation, demonstrated a considerable advantage in favour of timber construction even if part is offset by higher maintenance costs.
One of the most striking examples of low-cost wooden housing is found in Malaysia, where mass-produced timber houses are made at an unusually low cost. The chief contributor to this development is the Federal Land Development Authority (FLDA) which provides settlers with 45-square metre timber houses under a hire-purchase arrangement at a cost of $500 to $600, or $12 per square metre. FLDA orders around 2 500 of these houses each year from private industry. The design follows to some extent that of the traditional Malay house, consisting of one bedroom, living room, dining room, kitchen, bathroom and verandah.
These are. of course, isolated examples. Nevertheless, in the case of timber-rich developing countries with warm-humid climates, they demonstrate that favourable results can be obtained if essential preconditions are met.
TABLE 3. - COMPARISON OF INCOME1 IN DEVELOPING COUNTRIES, 1965 AND 1970
|
|
Number of countries |
1965 |
19702 |
||
|
Average GDP |
Population |
Average GDP |
Population |
||
|
|
U.S. dollars |
Millions |
U.S. dollars |
Millions |
|
|
Developing countries with per caput GDP above $500 in 1965 |
23 |
702 |
117 |
813 |
134 |
|
All other developing countries ³ |
151 |
150 |
1 426 |
170 |
1 625 |
|
TOTAL DEVELOPING COUNTRIES |
174 |
185 |
1 543 |
219 |
1 759 |
|
TOTAL WORLD |
225 |
696 |
3 362 |
803 |
3 718 |
1In per caput GDP al 1970 market prices. - 2 Provisional FAO income series based on UN statistics of national accounts.- 3 Excluding China.
LEVELS OF INCOME AND HOUSE PURCHASING CAPACITY
Level of income is the most important of the economic factors influencing standard housing in developing countries. It can be measured (although somewhat inadequately) by gross domestic product (GDP).
As can be seen from Table 3, only 23 out of 174 developing countries, with population of 117 million, had an average per caput income of more than $500 in 1965. All other countries, accounting together for 1426 million people, had an average of $150 per caput per year.
As a general rule, a household in a developing country can afford a house valued at roughly three times its annual income. Assuming an average household of four, the average family home must not cost more than:
4 × 3 × annual per caput income
This indicates that the price range within which solutions for urban housing problems in most of the developing countries have to be found was in the order of $1800 per house in 1965 or $2 000 in 1970.
Obviously these figures are only general indicators and do not take into consideration the income distribution within and between countries. Out of the 151 countries with an average per caput GDP of &170 in 1970, 23 countries (representing a population of 1000 million) had an average GDP of only $104; for their conditions the average cost of a house must not exceed about &1250. In large cities, 20 to 40 percent of the cost goes into the acquisition of a building plot. The remainder is usually just enough for the simplest form of shelter. Where timber is readily available it is used, rarely for wall construction, but almost everywhere for beams, partitions, eave boards, doors and windows.
Based on cost examples given in the previous section, and remembering that these cost figures are related to rather favourable conditions not generally prevailing at present, it can be seen that a large share of the population of the developing world appears destined to live in substandard settlements, unless definite long-term policies and programmes are formulated and consistently implemented. An increased use of indigenous building materials, notably wood products, can play an important and twofold role in the overall strategy of attack on housing problems: wooden houses are likely to be cheaper and use local materials which should become available at gradually decreasing prices due to the improving economy of scale of processing operations; in turn, per caput income levels should rise due to accelerated development resulting from the expansion of forest industries.
FINANCING
Institutions that provide housing finance exist in most of the developing countries. There are building societies, savings and loan associations, land mortgage banks, housing cooperatives, housing banks, sociétés immobilières, credits sociaux and development banks. Most of these furnish loans only to upper- and upper middle-income investors. Some countries also have government-financed housing boards or trusts that subsidize low-income housing through low-interest loans. The activities of the private financing institutions are limited by the small number of investors who can afford their terms, and those of the public bodies by shortage of capital that can be invested at noneconomic terms. Both together affect only a small section of the housing market. A recent sample survey in Kampala, Uganda, has shown that less than 14 percent of the houses in the city were built with help from the Government or housing finance institutions (8).
It is a fundamental law of housing finance that a house pledged as security for a loan must have a life expectation that extends beyond the repayment period. This is considered so obvious and self-evident that it is rarely put in permit or writing. Yet it exercises a powerful influence on decisions to make available or withhold finance from a housing project. In the absence of statistical evidence on the durability of houses in tropical cities, bankers and their surveyors and valuers will take a lot of convincing before they abandon the notion that inorganic materials are better and more worthy of financial support than timber and other organic materials.
Thus, without a major change in financial institutions and their approach to finance for housing, timber for a long time to come will be more freely used in the houses of the self-financing section, which is poorer but much larger in number than the privileged minority that benefits from institutional finance.
SEASONING, GRADING, QUALITY CONTROL
Seasoning6
(6 This section was contributed by C.K. Tack, of the Forest Products Laboratory, Princes Risborough, United Kingdom.)
Most building materials are subject to dimensional changes in use, due either to temperature or moisture content variations. Wood is hydroscopic and responds to changes in atmospheric humidity by shrinking or swelling with loss or gain in moisture content. This " movement" is usually negligible along the length but can be of importance in the cross section and must be taken into account in the design of joints, whether of timber to timber or between timber and other materials. The integrity of such joints is of fundamental importance if minimal maintenance and long service of the building are to be ensured.
In drying from the green state to in-service levels of moisture content, shrinkage can be considerable and may be accompanied by excessive distortion, checking and splitting, unless drying conditions are controlled. To avoid this green timbers must be dried or seasoned before use. Seasoning also helps in the successful application of finishes, prevention of decay, and in the treatment of nondurable timber with preservative.
In warm-humid climates air seasoning will be sufficient, as the in-service moisture content of timber in buildings (except when air conditioned) will approximate that obtained out of doors under cover.
Timber may be air seasoned or kiln dried. Air seasoning is lengthy and dependent on climate, but it does not need expensive installations and scarce skills, and permits a limited measure of control over drying conditions. In areas of high rainfall the roofing of drying stacks is essential. Where kiln drying facilities are available, drying under closely controlled conditions will produce quicker and more reliable results. However, in developing countries kiln drying may not give the monetary advantages which are usual in more advanced economies. Another possibility would be forced drying, a method of speeding up the air drying process at a reduced capital cost.
Seasoning need not be a technical restraint on the use of wood in the developing countries. The layout, equipment and organization of an air seasoning yard are comparatively simple. The problem is financial. The storage of timber for seasoning locks up capital for several months, even in the tropics. Kiln drying involves capital investment, expensive skills and relatively high maintenance costs, and capital and skilled men are just what the developing countries are short of.
GRADING AND QUALITY CONTROL 7
(7This section was contributed by D.T. Priest, of the Forest Products Laboratory, Princes Risborough, United Kingdom.)
Extensive use of timber in housing is possible only if stocks of the right type in required dimensions or standards, properly graded and of requisite quality are available on the market. Until recently standards, grades and quality controls had been lacking in the developing countries except in respect of the few exportable species.
The major softwood-producing countries each have their own set or sets of grading rules. These are generally based on a defect system of grading where a maximum allowable size or amount of each type of defect is specified for each grade, usually in terms of the dimensions of the piece. The defects usually considered are knots, shakes and splits, wane, distortion, discoloration and decay, and the dominant defect in the piece will determine the appropriate grade. For marketing purposes the higher grades are often grouped together and referred to as unsorted. Individual grades in any one set of rules are not usually directly comparable with grades from another set, but approximate equivalents are recognized. The higher grade material is used mainly for joinery and highly stressed components while lower grades are used for general construction such as house framing and roof trusses. Softwood grading rules are published for Norway, Finland, Poland, Sweden, the United Kingdom, eastern Canada and the Pacific coast of North America. The U.S.S.R. rules are not published.
Other regions which produce commercially important quantities of sawn hardwoods either market their timber under rules drawn up specifically for their own major species or they use some form of the general rules used in North America or Malaysia. In many cases these rules are drawn up for export requirements and therefore are not usually applicable to domestic purposes.
Some countries have now attempted to institute grading rules and quality control for timbers for use in construction. India, for instance, has formulated standard specifications and classification by species. East Africa has introduced a promising system of quality control by performance specification. According to Campbell (12) " this permits lower grades of timber to be used for construction, places the control of timber quality in the hands of the designer, is simple and can be implemented without waiting for local grading rules to be developed."
WOOD PRESERVATION
Many timber species are not naturally durable and are attacked by termites, fungi or borers, either alone or in combination.8 With the exception of the Arctic regions, one or several of these wood-destroying agencies can be found wherever timber is used. The incidence of attack is increased in warmer climates. As the majority of the developing countries are in tropical regions, the protection of building timber against biological degradation or insect attack becomes essential. Preservative treatment of secondary species that are not naturally durable would make them equivalent in service performance to primary species, which may be in short supply and reserved mainly for export purposes.
(8This subject is covered in Section 4, Part 1, and its background papers.)
A variety of chemical products and treatment techniques are available for the control of wood-destroying fungi, termites and insect borers. The methods of treatment most commonly employed are either chemical or mechanical.
Chemical barriers
Brush, dip and spraying. These methods of application to seasoned timber do not generally provide sufficient depth of penetration of the preservative to prevent attack if the timber is subsequently cut or drilled or if checking or splitting takes place. Improved results can be obtained by the use of low viscosity solvents but even in this case little or no control over the standard of treatment can be exercised.
Hot and cold open tank process. Improved depths of penetration can be obtained using this process although the degree of absorption varies considerably. This method requires slightly more capital expenditure in that at least one tank and a source of heat are required. Impregnation is achieved by heating the timber in the preservative and then letting it cool, or dipping it in another tank containing cool preservative. This causes contraction of the air within the wood and drives the preservative solution deeper.
Diffusion treatment. In this case water-borne preservatives are introduced into the green timber immediately after sawing. This method does not require transportation of the timber to a central treatment plant. It is best undertaken near the point of felling and good treatments have been achieved in a number of species which have been found difficult to treat by other processes. It is important to exercise careful control at the treatment site to make sure that the initial moisture content is sufficiently high and that the wood is carefully stacked under conditions of high humidity in order to allow maximum diffusion to take place. It is possible in certain cases for machining to take place after treatment, but because of the water-soluble chemicals used wood treated in this way can only be used internally. For external use a permanent paint film has to be applied. Another process used in the United States, the double-diffusion method, makes water-based preservatives insoluble. (See Section 4, Part 1.)
Vacuum pressure impregnation. A vacuum pressure plant has a higher capital cost than any of the other systems. It is not normally feasible to install it at sawmills. :It is more common for centralized treatment depots to be established, either on an independent basis or under the control of larger sawmillers or contractors. With this treatment it is possible to achieve full penetration of the susceptible sapwood and, in the case of some species, even penetration of the heartwood. It is possible also to control the amount of chemicals deposited within the timber. Timbers treated by vacuum pressure with chemicals which become fixed in them and do not wash out, such as copper chrome arsenical (CCA) products, can be used under all exposed conditions, including contact with the ground (see Table 4). Vacuum pressure should only be carried out on seasoned timber, which should have been cut before treatment to its final dimensions.
Mechanical methods
Physical barriers can prevent termites from gaining access to wood. Various methods have been devised to afford protection from attack by subterranean termites, including the provision of a projecting concrete slab over the whole plinth and a concrete apron around the building. Other methods include the use of protruding metal caps at the top of pillars, a continuous concrete slab around foundation walls of brick masonry and the application of a variety of chemicals as soil poisons or repellents. Mechanical barriers and soil poisoning have the advantage of protecting not only structural timber but also the contents of the building, including carpets, books, draperies, clothes, and so on. None of these methods can be regarded as completely satisfactory and all are ineffective against dry-wood termites.
PROSPECTS OF TIMBER TREATMENT
The rural people of the tropics for many centuries used perishable materials for their houses and accepted the necessity for frequent replacement. This applied to timber as much as to earth or thatch.
With migration to the cities these attitudes underwent a gradual change. The city dweller learned to think in monetary terms, he had a full-time job and started to resent the idea of spending all his spare time and cash on repairs and replacement of the worn-out parts of his house. He began to prefer durable materials. The appreciation of the benefits of treated timber is closely connected with this general change in attitude toward buildings and building materials.
In general terms the cost of protective treatment adds between 10 and 20 percent to the cost of the sawn lumber, and therefore approximately 5 percent to the total cost of a small all-wood house. This added cost must be regarded as a vital insurance premium for the house. It gives permanent protection to the timber, thus ensuring lifetime service. It also provides security for the mortgaging or renting authorities that carry the financial risk during the tenant's or mortgagee's occupation.9
(9 Some small sawmillers or timber suppliers have resisted the introduction of preserved timber in the belief that the market for the "placement of timbers that have been attacked by termites, fungi, etc., would be reduced or disappear. This attitude has not helped the timber industry. On the contrary, it has furthered the introduction of competitive materials such as steel and concrete and thus reduced opportunities for the growth of the timber market.)
In a number of countries legislation or encouragement by government has led to the establishment of a sound and widely established preservation industry. Good examples are found in Malaysia and Chile, where the use of preserved lumber in low-cost and traditional housing is widespread. It has been estimated that approximately 2 000 vacuum pressure plants are in existence throughout the world, about 80 percent of which are using water-borne preservatives particularly suited for housing-timber treatment. It has been estimated also that there are at least 700 or 800 plants in tropical and subtropical countries and that many of these are working at only about one third of their 24-hour capacity. In addition, a large number of dipping plants are operating in developing countries. Many of these consist of little more than a steel drum for dipping and a store of preservatives. Most treatment plants have been established in urban regions near the centres of consumption. Many of the suppliers of treatment plant and machinery offer credit on favourable terms in order to reduce the high initial investment. The increased use of treatment will allow (depending on the process applied):
the use of secondary species with less natural durability;
use of cladding without protective finishes; and
the use of treated timber for wooden foundations, piles, piers, rafts, etc.
TABLE 4. - MAIN METHODS OF TIMBER PRESERVATION
|
Timber usage |
Method of treatment |
Hazard |
Preservative requirements |
Preservative recommended |
|
Ground contact piers, piles, fencing, etc. |
Vacuum pressure impregnation |
Termites, borers and fungus attack |
Nonleachable with all-round effectiveness |
Creosote, pentachlorophenol, copper-chrome-arsenic, zinc-chrome-arsenic, fluor-chrome-arsenic, etc. |
|
Exterior timbers not in ground contact |
Vacuum pressure impregnation or hot and cold dipping |
Termites, borers and fungus attack |
Nonleachable with all-round effectiveness |
Creosete, pentachlorophenol, copper-chrome-arsenic, etc. Copper naphthanate and other suitable proprietary preservatives |
|
Interior timbers |
Vacuum pressure impregnation, hot and cold dipping and diffusion |
Termites, borers and fungus attack |
Preservative action sufficient to control all types of degradation |
Appropriate water-borne organic solvent products |
Table 4 shows treatment methods recommended for housing in developing countries.
FIRE PROTECTION
There is hardly a person in a fast-growing city of a developing country who has not witnessed one of the disastrous fires that have swept from time to time through the squatters' colonies near the city centre. The emotional impact of such fires has been strong because, prior to the arrival of the squatters, fires were a rare occurrence in the cities of the warm-humid tropics. This was due to the absence of domestic heating, the preference for hard wall and floor surfaces, minimal furnishings with no curtains and upholstery, and the custom of cooking in outhouses. Only the large cities had adequate fire services.
The growth of shanty towns has changed all this: they have revived memories of village fires that spread with frightening speed from one thatched hut to the other. The people of the fast-growing and overcrowded cities in developing countries are unlikely to know that wood is, in fact, not at all easily ignited and can resist the passage of flames for considerable periods and that fires usually start by burning contents, rather than by parts of the construction itself (9). They would be surprised to learn that steel trusses collapse at lower temperatures than wooden ones and that an asbestos-faced timber door is a safer barrier against fire than an all-steel door.
Very little is being done at present to counteract the prejudices against the use of timber in the cities of developing countries. There is little hope of change without an instructive campaign based on facts and research results, directed not only at home builders, but also architects, public works engineers, contractors. administrators, insurance officials and people of influence.
The economic conditions of the developing countries limit the choice of methods of using timber in housing. Nonstructural uses (for joinery, built-in furniture, etc.). however, are on the increase throughout the world10 and the developing countries are likely to follow the general trend, although more slowly.
(10 See Section 5.)
Structural timber can be used in housing in one or more of the following forms:
Load-bearing timber structures. These include all buildings with wooden posts, beams, roof trusses, purlins and rafters. They are usually referred to as timber houses or whole timber structures, even when the outer skin (cladding) and the inner wall lining are made of other materials. They used to be the preferred construction method in the equatorial tropics, where timber is often readily available and always a perfect answer to climatic requirements.
Timber lining and cladding. Timber cladding was formerly considered a nonstructural use. Modern designers, however, have recognized the contribution a wooden skin can make to the strength and stiffness of the whole structure, and have used various forms of stressed skins to reduce post and beam sections and thereby the solid timber content of their buildings. Developing countries are likely to be slow in adopting any method that makes timber visible from the outside until they have overcome their prejudice against timber as a poor man's material.
Timber as formwork for concrete. This is another rapidly growing field of timber utilization. Since 1950 plywood, hardboard and particle board have become cheaper and are beginning to be widely used for form-work. The economic situation of the developing countries favours this form Of using timber. Most of them have the raw materials for the manufacture of concrete, but not those for steel. The preferred forms of concrete are those that require the minimum amount of steel. so in several developing countries shell vaults, domes, hyperbolic parabolae, etc., have been developed to a very high standard. Such forms are labour intensive, because they require elaborate formwork. Developing countries with their large reserves of semiskilled labour can be expected to use more and more shell concrete, first in public buildings and later possibly in housing.11
(11It is no accident that Mexico led the world in the art of spanning large rooms with shell concrete domes, and that the first experiments using igloo-type concrete domes for low-cost housing were made in Dakar, Senegal, in the early 1950s.)
PREFABRICATION
In view of the rapid rate of growth of the cities of the developing countries, one would expect an expanding market for industrially produced items of joinery and buildings components in timber. Doors, windows, louvres, sunshades, railings and roof components should find a steady market, provided the individual items are light and small enough to be carried to the building site in peasant carts, on bicycles or as head loads, and can be assembled and placed in position without the aid of cranes or other mechanical tools.
In most developing countries the progress of timber component industries has been disappointingly slow. In the cities of west Africa and north India, the mass manufacture of steel windows has progressed faster than that of timber windows. Causes are difficult to assess. They may lie in the underdeveloped state of the local timber industries or in a lack of dimensional standardization, or both.
There is little immediate prospect for whole-house prefabrication or the manufacture of large preassembled and finished wall panels. Even the most efficient prefabricated wall unit cannot compete with locally available materials. The economic gains from prefabrication occur where labour costs are high, which is not the case in developing countries. The prospects are somewhat better for preassembled roof units. Roofs present a technical problem to the small home builder and the people of the tropics are used to paying cash for roofing materials.12
(12Two of the background papers (15 and 18) refer to substantial savings through the use of timber instead of steel trusses. Low-income houses do not normally require trusses, but it might pay to investigate whether the same methods could be applied to the use of timber to reduce costs of mass-manufactured ridge beams or purling for small houses.)
The only fields where large-scale timber prefabrication can play a role are emergency housing (for instance, in cases of earthquakes) and the housing of the workmen and supervisory staff of large public works projects. An example of the latter is the successful prefabricated timber house colony at Akosombo in Ghana. The houses were manufactured partly in England and partly in Ghana, and assembled at great speed for the workers of the Volta river dam. The Akosombo houses have been used intensively for ten years and are still in excellent condition. They now form part of a settlement that shows every sign of remaining permanent.
In considering the conclusions to be drawn from this analysis, it must be remembered that it has been based primarily on present circumstances, and that the negative factor of today can in many cases become the positive factor of tomorrow, if appropriate action is taken.
POSITIVE FACTORS
Favourable conditions for the increased use of wood in housing in developing countries contain some of the basic ingredients for expansion and development generally. Most important among these are the economic forces at work in these countries. Urbanization and other factors are creating an ever-increasing demand for housing. Costs of imported building materials are rising, and governments find themselves under pressure to develop the use of indigenous materials, particularly timber. The development of infrastructure, particularly road networks, has made great strides and will gradually make timber extraction less difficult.
Timber exports are increasingly directed at processed products: certain of these do not meet all qualitative requirements of export markets, but are suitable for a variety of purposes in the domestic building industry.
There are important elements of a house for which wood is the most suitable and economic material.
Prices for plywood and particle board have come down and manufacturing techniques have improved considerably.
The number of plants for the treatment of timber against biological attack is increasing. Urban house builders are beginning to appreciate that treatment costs are minimal and the gains immense.
Favourable social factors include the age-old traditions of timber handling and working in the villages of the warm-humid tropics, the continuing use of wood in rural housing and the transfer of these rural skills to the cities through internal migration. One should also add the awakening national pride of the developing countries which seeks expression in attempts to revive ancient traditions of craftmanship in wood.
Climatic conditions in the warm-humid tropics, which include many of the developing countries, favour forest-type vegetation, and indeed these areas contain three fifths of the world's forest cover. At the same time it is in these particular climatic zones that timber is the most suitable building material, due to its thermal and structural properties. Timber also has special advantages in earthquake and hurricane areas.
NEGATIVE FACTORS
A considerable number of factors militate against the use of wood in housing.
Social prejudice exists against wood as a house building material. It is regarded as a poor man's material as it is so commonly used in shanty towns. Also it is generally considered to be less durable than other materials and to constitute an increased fire risk.
Supply of timber products is deficient in most developing countries. Tropical forests have far fewer usable trees per hectare than those of the moderate climates, and this increases the cost of extraction. A large part of the sawmilling industry is obsolete, and many countries do not have a wood-based panels industry because the economic scale of operation involved exceeds the limited local markets.
Rudimentary marketing and distribution arrangements do not make timber products easily available where and when required.
As far as technical aspects are concerned, there is insufficient knowledge of many wood species that are found in the developing countries. Seasoning practices are in most cases poor. There are inadequate grading rules, and standardization is often lacking, as is the preservation treatment of nondurable species.
THE BALANCE SHEET
Weighing negative and positive factors against each other it appears that, if matters are left as they are, wood will not have a real opportunity to play its potential role in alleviating the world's housing problem.
However, many of the factors currently listed as negative can be converted into positive. For example, current deficiencies in seasoning, grading and preservation militate against the use of wood, but if removed would turn the scales in favour of wood as a building material. Supply problems, and the related question of timber costs, are very much due to the fact that the resource is not being used in sufficient quantities to enable rationalization of the extraction and processing industries; an increased market will lead to improved supplies and lower costs. An important factor mentioned is that of low levels of income: increasing domestic demand will stimulate the development of the forestry and forest industries sector and consequently raise employment and income levels.
In view of the fact that an increased use of wood in housing could help solve the world housing problem, measures to overcome the negative factors and build on the positive are urgently needed. They call for action by national governments and international organizations. Although their roles will in many senses be complementary, it is perhaps best to consider each separately.
THE ROLE OF NATIONAL GOVERNMENTS
Unless there are dramatic institutional changes, for a long time to come the provision of housing in developing countries will depend upon self-help and individual initiative. Neither local nor national governments can afford to build houses for all their people. However, they can assist in tasks that the individual house builder cannot do himself. In matters directly concerning house building, they can provide the necessary infrastructure such as access roads, drainage, water supplies and land. Governments can and should help their people to help themselves. This implies that they can exercise only an indirect influence on the type of houses people build, and the materials they use. But, as regards the supply of construction timber on an economic basis there is much that governments can do indirectly to counteract the negative factors mentioned above. In developing countries the indirect powers wielded by governments are formidable. and if used energetically and wisely can do a great deal to change the rather sombre picture of social and economic constraints, and remove most of the technical impediments that militate against the use of wood in housing.
A government that wishes to use its forest resources efficiently to contribute to the solution of its housing problems must set itself two tasks:
to make sure that timber products of the right kind are available in the right quantities, at the right time, and in areas of house-building activities;
at the same time it must encourage the widespread and national use of timber products in housing.
MAKING TIMBER PRODUCTS AVAILABLE
The first prerequisite is a sound forest policy geared to serve local needs as much as the export trade. Moreover, general development schemes such as roads, railways and other communications should always include consideration of the infrastructural requirements of logging and extraction. These are matters over which governments have direct control.
In the context of forest policy, governments could encourage and, if need be, enforce the utilization of lesser known species to provide more building materials without affecting the quantities of prime species for export.
National governments could use economic levers to encourage the modernization and expansion of forest industries. They also have the means to ensure that such industries that are established fit into a planned, overall supply-processing-marketing network.
In many developing countries the considerable fragmentation of forest industries prevents a continuous flow of timber products of appropriate quality and sizes. One way of overcoming this deficiency would be for governments to pursue a deliberate policy of encouraging the establishment of central timber yards capable of seasoning and storing large stocks of timber obtained, on a cooperative basis, from the smaller producers. These central timber yards should also be responsible for grading, preservation and precutting of timber products.
As advancing technology changes the competitive position of wood as a building material, coordination of research and demonstration activities between forest products laboratories and building research organizations should be strengthened to lay the foundation for sound long-term development of forest industries as a major supplier of the building sector.
PROMOTING MARKET FOR TIMBER IN HOUSING
The second task is very different. It involves fighting the prejudices against timber that have grown up in the cities of the developing countries. Timber must be accepted for what it is, a durable material for high quality building. The first to accept it as such must be the government's own construction agencies, particularly the public works department. Their house-building activities are insignificant as far as quantity is concerned, but are important insofar as they set an example for scores of thousands of private builders.
Even more important than the quarters for senior officials built by the public works department are the houses of the very rich, of public heroes and accepted and admired leaders of public opinion. Wood will cease to be the poor man's material when these public figures begin to build their houses in timber.
The introduction of building by-laws and regulations and the revision of those prejudicial to wood (often inherited from colonial administrations) may be necessary to counter social and cultural impediments. Promotion for the increased use of wood in housing should utilize all the mass communication media available to the government and should not be limited to publication in scientific journals.
It may seem excessive to expect a government to set a fashion. Yet the history of styles of dressing, decorating or building should be enough to show that it has been done and could be done again.
THE ROLE OF INTERNATIONAL ORGANIZATIONS
The production of building materials should be predominantly based on indigenous resources, and forests commonly constitute one of the major local resources. Examining the potential of these resources and the best ways of processing and utilizing a great variety of wood species is a major task of many developing countries. It is exactly this task which most of the projects sponsored by the United Nations Development Programme (UNDP), and executed by FAO, are helping to solve. At present FAO is executing 61 forestry projects in 50 countries, and 80 percent of these are concerned with overall forest industries development. They usually include pilot processing plants such as sawmills, preservation facilities, etc. This demonstration component of the field project should, however, go beyond the point of simply proving the feasibility of producing wood products for the market. It is essential that the practical applications of these products are also demonstrated. At present only a few projects include an element covering the actual building of houses from wooden components. A major effort should be made to expand this aspect of field activities so that, in the future, the majority of projects dealing with wood-processing industries also include schemes for demonstrating the practical application of wooden building components. Tasks of this kind can be solved by cooperation between the various international organizations involved, particularly UNDP, FAO, the United Nations Centre for Housing, Building and Planning, UNIDO, ILO and the regional economic commissions.
There is a wide range of other problems to which international organizations can contribute solutions. They can supplement government promotion activity with their documentation services. They can contribute much to the promotion and coordination of research activities on a regional and subregional basis. They can also assist in the transfer of technology through the establishment of regional or subregional training centres in the field on the production and use of wooden housing components.
(1) HAGMÜLLER, G. 1970 A noose around the city. Ceres, (18): 44-47. Rome.
(2) UNITED NATIONS. 1967 Methods of estimating housing needs. New York. ST/STAT/SER. F/12.
(3) DALDY, A.F. 1969 Regulations for small buildings in earthquake areas. London, HMSO. (Building Research Station, Garston)
(4) GARSTON, ENGLAND. BUILDING RESEARCH STATION. 1959 Building in earthquake areas. London, HMSO. Overseas Building Note No. 63.
(5) MUNTAZ, G.F. BABAR KHAN. Transition: a study of the community in the north of Ghana. Kumasi, Ghana, Faculty of Architecture, University of Science and Technology. (Unpublished)
(6) CROOKE, PATRICK. 1967 Rural settlement and housing trends in a developing country: an example in Nigeria. International Labour Review, 76 (3), September 1967.
(7) FALCONER, J.P.R. 1970 A building system for Ghanaian housing. Paper submitted to American Institute of Architects' Research Conference, U.S.A., 1970.
(8) LUBEGA, A. 1969 The financing and production of private houses in urban districts of Kampala, Uganda. London. (Thesis)
(9) DESCH, H.E. 1968 Timber: its structure and properties. 4th ed. London, Macmillan.
BACKGROUND PAPERS
(10) BARROSO, J.R. & TINTO, J.C. 1971 Utilización de la madera para la vivienda en un país deficitario en esta materia. WCH/71/6/7.
(11) BURGESS, H.J. 1971 Experience with the promotion of wood in housing in the tropics.
(12) CAMPBELL, P.A. 1971 Performance specifications for the quality control of timber for housing in developing countries. WCH/71/6/2.
(13) FALCONER, J.P.R. 1971 Design and production of tropical timber housing. WCH/71/6/6.
(14) GUISCAFRE, J. 1971 Le bois dans la construction en Afrique tropicale francophone. WCH/71/6/9.
(15) MASANI, N.J. 1971 Experience with timber engineering in the tropics. WCH/71/6/5.
(16) NOEL, G.A., BÉCHARD, J. & HUYGEN, J.P. 1971 Aspects pratiques de l'emploi du bois dans le logement dans les projects PNUD/FAO. WCH/71/6/10.
(17) ROBLES, G. & TENG, I. 1971 Wood in housing in Chile.
(18) STOKES, J.G. 1971 Wood in housing in South East Asia and the Pacific areas. WCH/71/6/4.
SPECIAL PAPERS
(19) FINNSIO, C.T. 1971 Review of the use of wood in housing in Africa. FO: WH/71 /21.
(20) HAGMÜLLER G.A. 1971 Review of the use of wood in housing in Asia and the Far East. FO:WH/71/43.
(21) MARRA, A.A. 1971 The elements of wood in housing and their relationship to resources and processes. FO:WH/71/45.
(22) TENG, J. 1971 Review of the use of wood in housing in Latin America. FO:WH/71/15.
1. The use of wood in housing in developing countries was a constant theme throughout the discussions of the Consultation, but under Section 6 the whole range of problems was looked at from the special viewpoint of the developing countries and against the broad background of their social and economic situations.
2. The Consultation reviewed the geophysical, social, economic and technical aspects of the situation. It attempted a prognosis by juxtaposing factors working for and against the use of wood in housing. It concluded that the use of wood in housing in developing countries would decline unless appropriate policies were adopted and action programmes undertaken. On this basis it suggested measures aimed at the improvement of the supply of timber and development of markets for wood-based building materials.
3. The discussions centred around four major subjects: qualitative and quantitative improvement of timber supply; development and improvement of design and construction techniques; market development; and questions of education and information services.
4. The Consultation recognized as key issues the improvement in the quality of wood-based building materials and the securing of their steady flow to the building sector; access to forests must be improved; all worthwhile timber must be brought out; the sawmilling industry must be modernized; grading rules by end uses must be developed and enforced; seasoning and preservative treatment must become common practice.
5. The Consultation stressed that design and construction techniques must be appropriate to the economic capacity, climatic conditions, cultural traditions and social structure of the countries concerned. Residential layouts must take into consideration the use of wood in determining housing densities and the spacing of buildings. The possibility of higher densities through the use of timber in combination with other materials should be explored. Housing design should incorporate such innovations as manufacture of large components from small wood sections, the use of wood in stressed-skin structures and the application of new framing techniques.
6. The Consultation recognized that lack of consistent housing policies was one of the main obstacles to the development of a steady market for timber products. Market development demands dimensional standardization and consistent quality control. Continuing refinement in housing design should aim at strengthening the competitive position of wooden building materials.
7. The market for timber is strongly influenced by preferences based on social prejudices. and combatting them through example and education is an essential element of marketing strategy.
8. The Consultation noted that the trade pattern of several developing countries strongly influenced the use of wood in housing On the one hand there are countries with a considerable export of wood in log form with an underdeveloped sawnwood industry and an undersupplied domestic market. On the other hand, there are countries whose centres of population are distant from seaports. These are bound to rely on the domestic market, and this may gradually lead to the development of a viable wood industry that could supply the construction sector and perhaps, eventually, to exports of manufactured or semimanufactured timber components for housing.
9. The Consultation recognized the critical need for training timber technicians competent in the application of timber in housing and of developing suitable educational media and information services. Of special value would be a series of films on the use of wood in housing, video-tapes for consumer education, and reference works and manuals for practitioners. Forestry services and government building and housing authorities should develop information services on the use of timber in housing.
10. A number of specific points emerged from the discussions, and the Consultation recommended that:
(a) governments formulate clearly defined housing policies to ensure a steady demand for building materials based on indigenous resources, including forests;(b) governments take measures to stimulate the modernization of the timber processing industry in developing countries, primarily sawmilling, in order to ensure the manufacture of wood-based products of the qualities required by the building industry at a cost competitive with other building materials;
(c) government authorities in developing countries prepare specialized grading rules aimed at the main end uses of timber, in cooperation with manufacturers, builders, architects and engineers. In the absence of grading rules, architects and government construction departments could help to lay the foundations for such rules by including practical performance standards in their contract documents;
(d) a larger number of UNDP &Id projects with more experts, more testing, demonstration and training facilities be planned to reverse the present trend which is against the use of wood in urban and rural housing. Forestry and forest industries projects should not stop at the primary conversion stage but include also demonstration of end uses in the housing and construction sector, with due cooperation among the competent United Nations specialized agencies;
(e) a broader flow of bilateral aid be directed to countries which have the determination to embark on clearly defined programmes for solving their housing problems, using indigenous resources such as forests;
(f) governments and housing agencies in developing countries give attention to the recommendations contained in the UNIDO report, Production techniques for the use of wood in housing under conditions prevailing in developing countries (Vienna, 1969);
(g) technologies based on the use of short lengths and small sections of a large variety of wood species be given application to overcome the artificial " timber famine" from which several tropical countries presently suffer;
(h) technology of house construction be fitted to the level of the economy of the country by selecting. where applicable, labour-intensive and capital-saving methods of manufacture for building components and house construction; wood is a particularly versatile material that can be used at all levels of technology;
(i) in view of the rapid concentration of population and urbanization in developing countries, suitable materials, techniques and designs for multidwelling homes be developed, based on the use of wood in high-density urban areas;
(j) timber-deficient countries should approach the problem of the use of wood in housing from two angles: on the one hand concentrate on adopting wood-saving designs and technologies and, on the other, explore the possibilities of manufacturing materials which can be produced from wood of almost any size and quality and from agricultural residues (e.g., fibreboard, particle board, etc.);
(k) governments should encourage research in the production of roof coverings from indigenous raw materials for the special needs of housing in tropical countries;
(l) architects and building engineers should be included in forest departments and organizations concerned with the promotion of wood products;
(m) governments and international organizations should assist in:
organizing architectural competitions for the design of different types of timber houses as an effective means of stimulating new ideas and generating public interest in the use of wood in housingproducing educational films to demonstrate the best practices in the use and maintenance of wood in housing
preparing and publishing, on a national and subregional basis, manuals for the use of all those concerned with design, production and construction of timber houses and house components.
11. Finally, the Consultation recommended that the most important and practical parts of the documents presented to the Consultation, and contributions to the discussions (including illustrations and diagrams) be condensed into a single concise volume reviewing the " state of the art," for the widest possible distribution.
