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When, in the last section, we looked at what constituted a renewable material, it seemed that life itself was the essential element. Life, of course, can only exist with the help of minerals on the surface of the earth and energy from the sun; however, both of these resources are relatively permanent compared to most life forms. It seems then that life itself remains the most vulnerable and vital ingredient that lies behind the secret of sustainability. This section looks at those plant and animal products we use as materials in our homes, and how we can harvest them ecologically.
We should also remember to treat with respect all materials that have been part of living organisms. Many of us have become so alienated from life outside our towns and cities that we forget we rely totally on our living ecosystem. ‘What is also thought-provoking is the fact that our bodies are made up of atoms and molecules that have been part of many previous plants and animals, particles that are in constant interchange with the air, water, minerals, plants, and animals around us. We should not see ourselves as separate from this ecosystem; on the contrary, we are an integral part of it.
Considering all the products from living organisms, timber and its products are by far the most important for our housing; an analysis of the way timber is treated forms the major part of this section. We should not forget, though, the other plant and animal products, such as reeds, canes, kapok, and wool, which are briefly discussed toward the end of this section.
Timber is the ultimate ecological building material, so long as it is managed properly. It can be used for almost any part or element of the home. It is also one of the healthiest building materials and can be used as a natural regulator of indoor climate, helping to stabilize humidity. It is warm to the touch, absorbs sound, and remains unaffected by electromagnetism. Timber is also a natural insulator, which means it has valuable energy-saving characteristics. It requires a smaller quantity of energy to process than most materials, involving very little waste or pollution. It is recyclable and biodegradable, has a natural durability if kept dry, and has a high weight- to-strength ratio. It is also one of the most attractive building materials, coming in a wide range of colors and textures. Surely hard to beat!
If we are to use timber sensibly in home renovation, we need to under stand: the principles of sustainability; the destructive forces that are at present destroying the rainforests; our role in encouraging this destruction; and how to counteract this by knowing which timbers to avoid buying, particularly the tropical hardwoods. We also need to make sure that the timber and timber products we use are from sustainable sources. and , finally, we need to know how we can preserve the timber in our homes without the use of damaging chemicals.
The Destruction of the Rainforests
The destruction of rainforests is one of the most urgent ecological problems facing the world at the present time. Some people would rate it the most serious problem of all. There is a common misconception that the rainforests provide additional oxygen for the world, but this is largely untrue, since nearly all the oxygen produced by the trees is taken up by the animals and microorganisms that live within the rainforest. As well as being valuable in themselves, rainforests are particularly important as an air- conditioning and climatic control system for the planet. They also protect the soil from erosion and provide a habitat for innumerable living species.
Why then is the wholesale destruction of the rainforests continuing at an ever-increasing rate? Vested interests play an important part, although the timber loggers and exporters are dependent on importers, distributors, retailers, and —ultimately—on us as consumers.
in fact, a study carried out by the Oxford Forestry Institute has estimated that 90% of revenues from the products of timber from the rain- forests go to the individuals, companies, and agencies in the importing countries. Less than 1% goes to the government of the exporting country. The result is that the governments of some tropical countries may receive less in timber revenues than it actually costs to run their forestry services. The worst affected and most vulnerable ecosystems are the tropical rain- forests of Africa, Asia, Malaysia, and South America.
Besides the logging of tropical rainforests, there are many other ways that these forests are under threat. The felling and burning of trees to make way for cattle ranches, roads, and short-term smallholdings are taking their toll as well. In temperate climates, acid rain is affecting more than a quarter of all trees, and the pressures on land for development are often heavy. However, perhaps the greatest threat comes from our insatiable demand for paper. Recycling is not a comprehensive solution, as paper is not as easy to recycle as many think: the ink first needs to be washed out and the quality of the fibers is reduced in the process. In many parts of the world timber has been the traditional household fuel, but population pressures and desertification are combining to denude even impoverished landscapes of their greenery. and , with the changes in climate due to global warming, forest fires are becoming an increasing threat in some areas.
Sustainable Forest Management
In Britain and North America there are, of course, many forest management practices that are less than beneficial, such as the wholesale clear- cutting and replanting of large wooded tracts. Sustainable multi-use management of deciduous forests, on the other hand, provides an ecological way of managing the renewal of timber and other resources. From an agricultural point of view, there is increasing interest in tree farming, and a growing realization that this also makes sense from the standpoint of good forestry. Areas of forest can be zoned for different activities and experiments carried out using different mixes of species. Animal life becomes an integral part of the scheme by providing habitats for species that need to be encouraged, as well as sanctuaries for wildlife under threat. Timber harvesting in the multiple-use forest requires a careful balancing of rates of extraction, including some benign neglect. Disturbance is kept to a minimum. All we are doing is allowing nature to act in the most efficient way she knows, and this requires us to understand better the ways in which she works and get in the way as little as possible. Overexploitation is usually prevented by only cutting trees of particular diameters. However, more sophisticated ecological methods of management will be developed as our understanding of natural cycles grows, and as we learn from the under standing and experience of native peoples who have lived for centuries in harmony with their forest environment.
At present there are very few forests in the world that are being managed based on these principles, and many timber managers remain ignorant of all of the forest’s potential benefits. The reestablishment of trees in areas of devastation is one way to heal and revitalize areas that would otherwise be barren. This can make an immeasurable contribution to redeeming the environment, and offer an ideal use for areas where industry or agriculture are neither present nor desirable.
How to Avoid Buying Unsustainable Timbers
Since a recent study for the International Tropical Timber Organization (ITTO) found that less than 0.2% of tropical forests are being managed sustainably, it might make sense to avoid using tropical hardwoods altogether until it is clear that the problems of sustainability have been over come.
However, if you are determined to use tropical hardwoods for a particular premium purpose, at least make sure that the source of timber is certified as being the product of managed, sustainable forestry by the relevant government agency in the country of origin. It may be very difficult to be sure of what you are being sold, so it is worth reading up on the subject with the help of the many guides available such as The Good Wood Guide (see REFERENCES). Pressure from knowledgeable consumers may help as much as a total boycott.
In most cases—and this applies to virtually all building joinery, such as window frames, staircases, and standard doors—substitution of temperate hardwoods and softwoods for tropical woods is always possible. Unfortunately, it is very easy to be sold tropical hardwoods as a component in plywoods or other types of boards used for building purposes. This is an appalling waste of valuable timber, which should be conserved for special uses. Many British board importers and suppliers are now making an effort to improve the quality of plywoods made from temperate sources.
Tropical Hardwoods We Can Use
In most cases we should avoid using tropical hardwoods. However, there are a limited number of woods that come from sustainable sources and whose use should be encouraged in preference to other timbers:
Temperate Hardwoods We Can Use
The following list details woods with characteristics that make them ideal replacements for tropical hardwoods. Some are especially appropriate for externally exposed joinery such as window frames, and others for use in internal joinery. Native hardwoods often have a greater inherent resistance to pests and weathering than many of the exotic timbers now widely used. The timbers listed below are increasingly available at competitive prices and in commercial quantities.
It is important to understand the properties of these different timbers: there are many books which give details of what to expect in terms of durability, stability, workability, and the likelihood of splitting. The more the pitfalls of any particular timber are understood, the more it is possible to find ways of overcoming these through correct detailing and design. It is particularly important to know how to design for protection with external use.
TIMBER PRODUCTS: EFFICIENCY and USE OF WASTE
There are many products that use timber as the main material:
• Medium-density fiberboard (MDF)
• Fiber insulating board
• Wood wool
At present many of these products contain tropical hardwoods and should be avoided. Some manufacturers are now returning to the use of indigenous regional timbers as demand for products made from these sources increases.
Formaldehyde glue is used in many of these products, including chip- board. With products containing formaldehyde, the main consideration is where the board is to be used. If it is indoors in a badly ventilated space or in a bedroom, it would be worth finding an alternative; formaldehyde-free materials are beginning to be easier to find and identify. However, there is always the choice of using these products and growing spider plants to absorb the formaldehyde vapor (see the PLANTS section in the HEALTH part of this guide).
Fiberboards such as hardboard, medium-density fiberboard, and insulation board are made of materials ranging from wood pulp to shredded sugar cane. Some of these are made in a way similar to paper, without the use of glues or synthetic resins. If you are keen to avoid products containing synthetic resins and formaldehyde, it may well be necessary to check with the manufacturers to find out how they are made.
Linoleum is a material which is coming back into use again, PVC having largely taken over its role in recent years. Linoleum is made of entirely natural products: powdered cork, linseed oil, wood resin, and wood flour, with the material being pressed onto a backing of burlap or jute. It is flexible and strong and comes in sheets or tiles. It feels warmer on the feet than PVC and is “softer” to the touch. It should be installed on a smooth, firm, and damp- proof surface with a lignin paste.
Cork is a renewable and environmentally benign material. It is the bark of the evergreen oak, Quercus suber, and the stripping of the cork bark surprisingly does no harm to the tree; in ten years time it is ready to be stripped again. The cells of the bark are filled with air and can withstand very high pressures without rupturing, returning to their former size when the pres sure is withdrawn. Cork is lightweight, durable, nonflammable, and excel lent for flooring, insulation, and veneers. It is produced on the Iberian Peninsula by small firms, and its use should be encouraged.
Natural rubber comes from the milky sap (latex) extracted from the rubber tree, Hevea brasiliensis. Inmost cases its uses have been replaced by synthetic rubber and plastic. It is still possible to obtain natural rubber floor tiles and natural rubber foam for furnishings. This is well worth doing, as the properties of natural latex in terms of durability and flexibility are superior in many ways to those of its synthetic substitutes. It also burns less easily and less toxically than many of the plastic foams used in furnishing. Oxidation is its main cause of degradation; protection from this process prolongs its life. Natural rubber is also used in adhesives, and to form resilient layers for underlayments and soundproofing.
The use of paper in newspapers, magazines and catalogs, and for business and office uses has resulted in the development of vast conifer forests solely to meet this demand. These forests are often ecologically barren, causing soil erosion and heightening the acidity of rivers and lakes. The process of papermaking itself can also be very polluting. This having been said, our insatiable appetite for paper lies mainly outside its use in the fabric of our homes, and its use in building should generally be encouraged.
In building, the main uses of paper are for wallpaper and drywall. Ecologically, wallpaper makes a wall finish preferable to most paints, which contain many toxic chemicals and can't easily be recycled. When wall paper is finished with, it can be stripped off and will bio degrade satisfactorily. This biodegradability is threatened, however, if thick layers of toxic synthetic colors are used.
Insulation from Recycled Newspapers
The use of processed waste paper as an insulation material is growing rapidly in popularity. Paper has insulating properties superior to fiberglass and mineral wool, its main competitors, if it is properly protected from dampness. Before use, the waste paper it is treated with borax to make it fire- and insect-resistant When installing this material, there is a choice of filling it In by hand or spray-blowing it into place.
AVOIDING TIMBER DECAY
Traditionally, the control of decay in timber has been achieved through proper seasoning and careful detailing. However, more recently there has been greater reliance by the timber trade and builders on the use of timber- preserving treatments in order to control rot and infestation. This has led to a general slackening of good seasoning practices and design that protect timber naturally. At the same time, there has been an increase in the sealing of buildings for energy conservation purposes, which has often increased the risk of condensation and reduced the ventilation that timbers need. Since we are now more aware of the toxic effects of many wood-preserving chemicals, we need to return to using the best traditional ways of controlling decay as well as developing new ones.
To season timber properly, the bark must be stripped and the log soaked in water to remove the sugars in the sap. These sugars can be a major factor in helping rot to gain a foothold in the wood. The soaking process, which so often is ignored, can be achieved either by floating logs in a river or pool or, alternatively, spraying them with water. Kiln-drying speeds up the process of drying out timber, but does not allow some kinds of wood sufficient time to stabilize. This not only wastes energy, but results in subsequent warping and shrinkage, leading to further waste.
With renovation work, we have two situations to deal with. First, any new work involving timber needs to be appropriately detailed to avoid future decay; second, the most ecological treatment of any decay that is found needs to be identified. In the case of new work, it is important to choose well- seasoned timber and to install it in such a way as to ensure that it will remain reasonably dry. The best way of doing this is to provide ventilation around the timber if it is situated near a potential source of moisture. Most traditional methods of building adhered to this principle by providing adequate ventilation both in the roof space of the house and the underfloor, where there is the greatest risk from either rain penetration or rising damp, respectively.
When treating rot in the existing structure, it is important to identify the cause of the decay. In most cases this will be a source of moisture combined with a lack of ventilation, often due to the sealing of ventilation routes or other means of moisture escape. By reducing any source of moisture, drying out the timber, and increasing ventilation, the problem should be solved so that there is no need for toxic timber treatment, which can often prove worthless in the long run anyway. In difficult cases it may be worth obtaining specialized help.
OTHER PLANT PRODUCTS
Besides timber there are many natural, renewable products derived from plants and animals. These include materials ranging from thatch to silk. A brief résumé is presented of each material and its properties.
Canes and Grasses
These materials have a relaxing quality about them. They are lightweight and have good insulating and acoustic properties. Bamboo in particular has been used very successfully for all manner of building functions. Thatch, of course, has been used in Britain for centuries as an effective roofing material. Now, however, some of these reeds are becoming the last remaining habitats for certain species of birds and animals. Such canes and grasses need to be cultivated in carefully managed plantations and fields.
Straw has long been used as a traditional material for roofing. However, it is not long-lasting and mechanical methods of harvesting tend to break up the straw. Norfolk reeds make a more appropriate thatching material (see below). Straw can be made into strawboard, which is used for roof decking among its other applications, thus using a material which is otherwise virtually wasted.
Reeds are much stronger than straw and are now the preferred material for thatching. The Norfolk reed is the best in Britain, growing to a height of about 8 feet. These reeds, once installed on a roof, can last as long as 50 to 60 years. However, it has been found that the use of nitrates weakens the durability of reeds, so organic sources need to be used for thatching. Reeds are also used for many types of matting. Such mats don’t last for very long if they are kept in too dry an atmosphere, but if sprayed with water occasionally their durability is greatly increased.
Bamboo is a kind of perennial grass that is not grown much in Britain except ornamentally. There would seem to be great opportunity to develop species that grow well in temperate climates (there are over 1,000 bamboo species in all). Its very high strength-to-weight ratio makes bamboo ideal for furniture. Wall panels, woven screens, and floor coverings are among its many other uses.
Fabrics and Fibers
Although cotton is widely used, many other natural fibers are going out of use because of the growth of synthetic substitutes. We need to rediscover the aesthetic and practical advantages of some of these materials.
Linen is an extremely strong natural fiber whose strength increases when wet. Linen made from flax has become expensive because its processing involves more elaborate processing than cotton. However, it is long-lasting and can be grown locally.
Produced from the cellulose fibers of the cotton seedpod, cotton is the most versatile of the natural fibers. It can be woven into a wide range of fabrics, from thin muslin to tough canvas. The ecological impact of intensive cotton growing can be considerable where there are very high chemical applications of pesticides and fertilizers. Also, irrigation demands can upset traditional water cycles, as has happened around the Aral Sea in the former Soviet Union. Many cotton materials are also highly treated with chemicals to give them different characteristics. For instance, urea formaldehyde is used to give cotton a no-iron, “permanent press” quality. The benefits of the use of cotton, as with the use of so many natural materials, are thus clouded by these considerations.
The silky fibers from the seed capsules of the silk-cotton tree (Ceiba pen tandra) can be used for the fillings of bedding and upholstery; however, when worn, the fibers break down to produce a dust to which some people are allergic.
Jute fibers are traditionally used for making burlap for use in sacking and wall coverings. Its main use in our homes is likely to be as the backing for linoleum and carpets.
The hemp plant produces strong coarse fibers used to make cord, rope, matting, and cloth. The main problem is that the growing of hemp or cannabis is strictly controlled because of the use of its dried leaves as a drug (marijuana). It also produces high-quality paper, owing to its long fibers.
Sisal fibers, from an American desert plant (Agave sisalina), are exception ally strong and can be made into cord and matting.
Coir comes from the coarse fibers of the outer protective husk of the coconut and is mainly used for door matting.
There are three main animal products in widespread use today: wool, silk, and leather. At present there is a glut of wool on the market due to competition from synthetic substitutes. However, natural wool is a strong, durable material and is almost certainly the most appropriate material for carpeting, ideally with burlap backing. It wears well and is healthier in the home than synthetic alternatives.
Silk is spun from the cocoons of a moth that no longer exists in the wild. It has an extremely strong weight-to-strength ratio and can be dyed most effectively into brilliant colors. It is used for special furnishing where a rich quality is desired.
Leather is used as a furnishing and upholstery material and is extremely hard-wearing if it is looked after properly.
PRIORITIES FOR ACTION
+ Choose sustainable sources of timber.
+ Avoid using tropical hardwoods except those mentioned above.
+ Become acquainted with indigenous hardwoods and use them where appropriate.
+ Use composite boards such as plywood and particleboards wherever they can result in more efficient use of timber.
+ Also consider using:
• other timber products, such as linoleum, cork, rubber, wallpaper, and cellulose insulation from newspapers
• grasses such as reeds, straw, and bamboo
• natural fibers, from linen to coir
• animal products—wool, silk, and leather
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