NON TIMBER BUILDING MATERIALS

There are nearly one hundred non-timber materials described and listed alphabetically below.

These materials are not endorsed purely because they are mentioned here. It is more the case that the Guide wishes to delineate their relative merits and faults. Mostly they represent ways of using either none, or significantly less amounts of timber in construction. Some of the materials may not be universally available, but are intended to exemplify just some of the limitless possibilities for safe, effective and durable shelter-creation.

The outstanding materials, in terms of their environmental friendliness, versatility, availability, and ease of use are: Bamboo, Biotecture, Earth, Grasses, and Hemp.

In general, once human and natural ethical concerns have been considered, choose natural materials which breathe (ie, are hygroscopic), rather than synthetic materials.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

ADOBE 1

Adobe bricks * are made from sun-baked clay. They have been used for millennia to build durable, well insulated dwellings in the warmer, drier regions of the earth, where the soil is suitable.

* See also the article Adobe & Super Block Technology

AERATED CONCRETE

Autoclaved Aerated Concrete* is made of quartz sand, lime, cement and water. It is a German innovation which has been used for house construction in Europe for decades, and is now used worldwide. Houses can be built more quickly and cheaply with such a lightweight material (1 cubic metre of raw material makes 5 cubic metres of AAC). CSR makes Hebel blocks and panels out of AAC, which is very light yet has excellent insulation properties, is fire and termite resistant, and reduces the amount of timber required to build a house to an acceptable standard. (The Wilderness Society recommends that consumers do not buy AAC or any other products from the Boral corporation due to its continuing insistence on putting the environment last by logging old growth forests for timber and woodchips.

The German parent company recycles its wastewater, steam (used in autoclaving), and solvents used in manufacture. Hebel blocks may have drawbacks, such as not providing a sufficiently firm substrate to anchor doors, fixtures and fittings (check with your builder re. a workaround for this).

* See under Non-Timber Building Materials in the Directory)

** Note: As at May 1998, CSR is embroiled in controversy over its attempts to establish a toxic waste dump in suburban Melbourne. Fortunately, and despite heavyweight political backing, CSR faces a formidable barrage of dissenting public opinion and direct action to prevent the dump's operation.

AEROSPACE MATERIALS

A new era of construction technology began in the seventies with the advent of so-called 'two-phase' or 'composite' materials ­ largely spurred on by the aerospace industry. Such materials consist of human-made fibres embedded in a matrix that holds them in parallel bundles. Fibreglass has been around for a long time, but more recently, human-grown fibres of boron, carbon and other elements have produced materials with amazing stiffness and strength-to-weight ratios. Engineers termed the technology 'the new science of strong materials', although it really is anything but new since all these composites are just human-made analogues of bamboo. The strength of the bamboo grass lies in bundles of fibres running the length of the culm held in a matrix of pith, just as it is in the 'new' strong materials. Bamboo spacecraft are not out of the question!

Carbon fibre, although a boon for such low-tech end uses as bike frames, boats, sporting equipment, etc, produces hazardous waste during its manufacture. Carbon fibre materials, if they must be used, are best purchased in Australia or the U.S., where environmental regulations for manufacturing are stricter than in other countries.

There is talk of researchers doing research on the potential for hemp fibre as an aerospace material ­ which makes a great deal of sense, since hemp is the longest and strongest fibre known.

ALUMINIUM

Used for window frames, light-weight mouldings, for roofing, walls. Should be used sparingly as aluminum production is a highly polluting and energy intensive process. Buy recycled aluminium window frames, for example.

(NB: If you decide to purchase new aluminium window frames, please specify that the window reveals must not be made from rainforest timber.)

ALUMINIUM CANS

Mobile home: A Japanese man in 1996 sailed 16,000 kilometres across the North Pacific in a solar-powered 9.5 metre boat made from 22,000 recycled aluminium cans.

The headquarters of Solar Survival Architecture * in Taos of the USA uses recycled cans as a building material.

* See under Architects in the Building section of the Directory.

ANIMAL HIDES

Yak, camel, goat, buffalo/bison, ox, bear, wolf, wildcat and beaver skins and many others have been used to shelter and clothe tribal people since antiquity. Animal hides are the traditional walls of choice for yurts, tipis, etc.

ANTIGRAVITY

Structures which are supported and/or held together by anti-gravity devices may well be in vogue in the not so distant future. An increasing amount of research-related literature continues to be generated by scientists and private researchers. (Probably the best way to get more info, is to enter the phrase 'anti-gravity' in an internet search engine.)

AQUATECTURE

Water as a building medium: New York architect Bill Ketavalos has beeen erecting structures using water encased in plastic membranes since the early nineties. He calls his creations Hydrodomes and Hydroarches. Walls, vaulted ceilings and arches can be built using plastic-enveloped water.

The technique involves creating a vacuum within the sealed plastic membrane which serves to draw the water upward in much the same way as does a drinking straw. It is cheap to build this way, there is no quarrying of the raw material, the finished product is flame-proof, and the vacuum seal means that any damage to the membrane will initially cause air to be drawn in rather than water to leak out! Aquatectures are good insulators for both heat and sound - the water may also be heated if necessary. The water can also act as a battery cell.

Mr Ketavalos has plans to build an underwater cathedral for catholic skindivers.

ASBESTOS

Asbestos is a general name for a group of fibrous silicate minerals which are now known to be carcinogenic. Originally it was used as for thermal insulation, in asbestos-cement roofing, wallboards, water pipe insulation, boiler pipe packing, paint, and fireproof gloves.

Asbestos fibres are very small, and when the parent material ages, the fibres are released and become airborne, where they can easily be inhaled, transported on clothing, or deposited in the soil, gutters, rainwater tanks, etc. Because of the danger to health, it is no longer used by the commercial building industry in Australia.

Most older buildings are having or have had any asbestos cladding or lining removed - a biohazardous process in itself for those involved. Owner builders using recycled materials in their home construction should never use any salvaged asbestos sheets, etc. Mesothelioma is the disease associated with exposure to airborne asbestos fibres or dust for any period of time.

For help in taking asbestos out of your home or office, etc, see 'Asbestos Removal' in the Sydney Yellow Pages or your local directory.

BAKELITE

Bakelite (invented by chemist Leo Baekeland at the turn of the century) is the trade name for a thermosetting plastic derived by heating phenol or cresol with formaldehyde and ammonia under pressure. It was used earlier this century for making radio cabinets, telephone receivers, electric insulators, and moulded plasticware, etc. Bakelite items these days are considered collector's items.

It is possible that bakelite items outgas formaldehyde.

BAMBOO

The world's most useful plant. Bamboo is a very large grass rather than a tree, yet has a timber-like quality when used as a construction material. It is the fastest growing plant in the world and certain species can reach heights of over 100 feet at rates of up to 5 centimetres per hour.

This botanical cousin to rice and corn has over 1,000 species of varying sizes and characteristics makes it amazingly versatile: it may be used for building whole houses, furniture, cases, baskets, screens, farm tools, fishing rods, windmill blades, boatbuilding, record needles, paper, kites, blowguns, polish, diesel fuel, scales, food, medicine, chopsticks, incense sticks, musical instruments, blinds, tipi poles, concrete reinforcement, plastic reinforcement, scaffolding, cables, bolt subsititutes, piping, bike frames, various other structures and a host of other durable, useful, crafted items. Perhaps the bamboo grove itself could be considered an 'item' in that it has traditionally been a place for contemplation and spiritual enlightenment.

Bamboo is also used for brewing beer. An Edison light bulb in the Smithsonian Institute in Washington, D.C. has a bamboo filament which is still capable of burning after more than a century. At one time, unscrupulous Assamese traders were fraudulently selling the carefully trimmed culms of a local bamboo species as genuine rhinoceros horn to the Chinese, who value the 'horn' for its aphrodisiacal properties. The bamboo cable-supported Min Bridge in Szechuan is over 1,000 years old.

With greater understanding of its qualities and propensities in the West, its reputation for invasiveness in the garden is now giving way to one of efficiency, workability, versatility, cost-effectiveness and earth-friendliness as a building medium. Due to its starch content, bamboo needs preserving to prevent borer attack and decay, but its cellulose content is also what makes it a source of paper pulp. Most of the bamboo used for manufacture (of mainly furniture and blinds) in Australia is imported from Southeast Asia, but plantations of the most useful species are springing up all over our country. (Note that China grows the most bamboo, while India is the largest exporter; but it is Japan which has traditionally been the greatest exploiter of the usefulness and beauty of bamboo).

When purchasing bamboo products, avoid any that have been treated with DDT solutions or similar to prevent borer damage. Instead, specify borax-treated bamboo.

(See also Rattan, under Cane. See Concrete in this list for information about bamboo-reinforced concrete. See the article Bamboo - the Rainforest's Universal, Renewable, Spiritual Resource. See Bamboo in the Building section and Bamboo in the Books section of the Directory.)

BAMBOO PLYWOOD

(See the article Bamboo Plywood, and Bamboo under Building, and Bamboo under Books, in the Directory.)

BANANA TRASH

Banana trash has been successfully woven or braided in Australia to make hats and bags. It is probably used in other countries as roofing material. The fibres are very strong and would be good for lashing.

(TREE) BARK

Bark roofs have been a part of Australian Aboriginal architecture since antiquity. Paperbark (melaleuca) and stringybark (eucalyptus) were just two of many barks commonly used, as was a combination of bark and brush. More recently, white settlers and squatters used bark to create a shingle-type coverings on the roofs of their sheds and dwellings if resources and/or finances prevented any other option.

BIOCEMENT, BIOCONCRETE

Biocement, a material still being developed, is a combination of crushed limestone aggregate, sand and cement.

(See Building with Concrete - the Hard Facts, and Innovative Civil Engineering Material from Sewage Sludge: Biocement And Its Use As Blended Cement Material in Books, Non Timber Building).

BIO-BRICKS

(See Sewage Sludge)

BIOPLASTICS

One of the better known proponents of biological plastics is Germany's Mercedes Benz, which is attempting to make their vehicles completely biodegradable, through the use of vegetable fibre-based plastics for body panels, etc - as did Henry Ford at the turn of the century. (See also Vegetable Fibre, below). This manufacture of bioplastic panels for cars is akin to the French developed product, Isochanvre, which is a hemp-based, flexible yet strong construction board.

(See also Hemp, below).

BIOTECTURE

German landscape architect, Rudolf Doernach is a designer of what he has termed biotectural systems. He has had to evolve a new vocabulary to describe his concepts:

Biotecture - is the design of multi-purpose plant shelters for human occupation with integral conservation and energy generation capacity.

Urbiotecture - is the process of creating a living layer of vegetation on the outer walls of houses, buildings and sheds, or the use of a layer of vegetation in place of walls of conventional, inert building materials. It has been practised in modern times in alternative communities in Europe, where it has a long history.

Agritecture - is house farming - a new branch of agriculture. It is the growth of buildings and building components (eg, biotectonic sod structures can be grown in about two months).

Hydrotecture ­ Plant and animal organisms ­ there are more than 2,000 species of them ­ live on the seabed. Their building products vary from mucous to shell-hard secretions. Light, oxygen, temperature, current, minerals and biocenosis ­ the balance of animal and vegetal partners ­ contribute to shape the colonies of these micro-organisms. For example, the serpulla build bowling-pin shaped hollow tubes of lime on ships hulls forming a crust of as much as one and a half inches a year. By immersing suitable cores in seawater, the biological builders, by colonising the cores or 'formwork' in any shape can construct building components for use on sea or land using only solar energy.

Doernach's creations produce incredible savings compared to inert construction/insulation materials and and have great potential for employment, given that say, 10 million homes have 100,000 hectares of plantable surface suitable for food cultivation. Insulation, energy-savings, noise-reduction, dust suppression, carbon dioxide conversion, oxygen production and psychological benefits are all positive by-products of planted walls. Or, to paraphrase a letter Rudolph wrote to the Permaculture Journal: "Become a low-riser, a gardener­biotect in a self-growing, energy-harvesting, air-delivered biotectonic plant shelter. Zero-energy and zero-cost habitat is possible, if you really want it. Who can teach you how to build it? Mother Nature!"

Biotecture also extends to the use of shelterbelts and windbreaks to modify the climate around and within a dwelling without modifying the dwelling itself.

(See the articles Biotecture, Pleaching and Living Fences. See also Naturwerkstatt and Plant Houses in Books, Building Design, and Biotectur Partner in Building, Architects. See Pleaching below - and back-issues 7 & 8 of the Permaculture Journal.)

BONE

Mammoth bones which were used as a structural framework for a covering of animal skins were an early form of shelter for nomadic hunter-gatherers in northern Europe. Such bones have been found in the Ukraine which date back to 50,000 BC.

BRICKS 1

A very versatile medium for construction and landscaping, although an energy-intensive process is required to manufacture them. Brick floors (as well as pise and rammed earth) are becoming increasingly popular with do-it-yourself and commercial home builders because of their thermal properties. Check out your local building recycler for second hand bricks.

Please don't buy new bricks from Boral - see note under Aerated Concrete in this section. (See also Sewage Sludge Bricks, below).

BUSH ROCK 1

In urban areas, bush rock (as opposed to quarried rock - see stone) is more often used for landscaping and decorative purposes than construction. This is due to the cost of sourcing and transporting natural rock. The use of rock taken from bushland has become quite contentious in this day and age, due to the ever-shrinking 'resource' (ie, the bush!).

In rural and/or isolated areas where there is a still a plentiful supply, it makes a cheap, ethical, stable and durable construction material.

CABLE NET STRUCTURES

Builder Chris Piper has devised a structure made of cable-tensioned steel mesh mounted on tall poles, which is based on the work of Frei Otto1, and Rudolf Doernach's and Stephen Lesiuk's 'biotecture' designs. The aim is to give people an 'instant' biotecture-type structure, which would otherwise take many years to grow. The cable net structure seeks to fulfil many criteria ­ close to nature, domestic and industrial applications, comfort, low cost ($25/sq m), multi-functionality, enviro-friendliness, microclimate control, low maintenance, ease of construction, food growing ('living pantry'), etc. Kitchen, sleeping, living, and working areas, etc are protected by waterproof membranes suspended under the mesh roof and thermally efficient strawbale walls. Gardens, orchards, aquacultures, ponds, in-ground or above-ground tanks and semi-outdoor areas under the roof can directly receive diverted runoff from the protected areas. The mesh roof, poles and cables can all be used to support food plants and vines. Various sectors of the roof can support evergreen or deciduous vines, depending on aspect. A more detailed description of the way the structure works and explanation of issues such as tensile strengths, pole installation, costings, and council approval can be read online at the Permaculture Journal's website.

(See also Steel, below)

1. Frei Otto created huge cable net tension structures spanning many hectares, as featured at the 1967 Montreal Expo.

CANE

'Cane' is really a generic term for the stem of palms, grasses and bamboos.

The long, trailing stems of the rattan plant (actually a species of palm) can grow hundreds of feet long, high into the canopies of tropical rainforests. It is mainly found in Malaysia, Borneo and the Philippines and India;some also grows in Australia's tropical and subtropical forests.

Rattan is ideal for furniture, thatching (very durable), wickerwork, mats, pots, rope, walking sticks, etc. Rainforest tribal cultures have used it for thousands of years. Unfortunately, overharvesting due to too high demand is making rattan scarce. Also, because of overlogging and rainforest destruction, many rattan species are in danger of extinction due to lack of habitat in which they can thrive. Several community projects in the tropics are now trying to cultivate it in plantations and/or ethically harvest their rattan.

NB: If purchasing a rattan product, specify that you do not want any material which has been treated with toxic chemicals such as DDT or Lindane, etc. Try and buy it untreated from a village-based craft supplier in a developing country, or an Australian community organisation which acts as an importer.

(For suppliers, look in your local Yellow Pages under 'Furniture, Cane & Wicker'. See also Bamboo)

CANVAS

Canvas is a heavy cloth which derives its name from the word "cannabis", the first real canvas. These days, cotton is the main source of raw material for canvas cloth, rather than flax or hemp. No tent, tipi*, tarpaulin or awning should be without it!

* For info on Tipis, see Books, Tipis and Tipi Manufacturers in the Directory.

CARBON

Carbon is often a component material in solar panels.

(Carbon Fibre: see under Aerospace Materials)

CARDBOARD

Two US companies, Gridcore and Simplex Products, make a fibreboard from cardboard boxes*, office waste, paper mill waste and manufacturing scrap. The board is very durable and, in Gridcore's case, envisaged as a substitute for plywood and/or gyprock.

* See also Building with Cardboard.

CAR TYRES

(See Tyres)

CELLULOSE

Cellulose is found in wood, coir, cotton, hemp, kapok, jute, paper, sisal and all vegetable tissue. A fibre of relatively modern origin, it is normally associated with cellophane 'plastic' and fabrics such as linen and rayon. Cellulose (ie, from recycled newsprint) is now being incorporated into buildings as thermal and acoustic insulation, as well as in vegetable plastics for packaging.

Cellulose glues are useful additives to make non-toxic surface sealers for masonry.

The AARCitecture Environmental Home, designed almost completely of agriculturally derived materials, is an 1,800-square-foot, passive solar, energy-efficient home designed and built by staff and students of a Colorado, U.S. university. The aim was to make the house both market competitiveness and low in environmental impact. The home's bio-based materials include structurally insulated wheat straw panels for the walls, floor, and roof. The designers incorporated soy panels with masonry units for the trombe wall. Corn, cork, jute, bamboo, and other cellulose-based materials make up the house's interior flooring, shelving, cabinetry, and built-in furniture details.

CEMENT 1

Cement in the form of mortar is the 'glue' for every conventional housebrick that gets laid and is the base material for every slab of concrete that is poured. The manufacture of cement* is very labour-intensive. It is usually made from alumina, lime, iron oxide and silica, which are burned together, then pulverized into the grey powdery substance we know as cement, which chemically hardens when mixed with water.

Composite materials, such as cement board may contain a mixture of portland cement, ground sand (silica), cellulose fibre and water. They are becoming very popular for cladding, panelling and screening in house and commercial building projects because of their durability, workability, lightness, fire resistance, termite and rot resistance, dimensional stability, and variety of textures.

A major drawback is that usually a chemical-based sealer must be used wherever there is a join in a cement board-based structure. Also, respiratory irritation, silicosis and even cancer are potential health hazards for people who cut cement board and regularly come into contact with the silica dust. Respiratory protective devices should always be worn when drilling, cutting or sanding cement board, and the workplace cleaned up of any dust, debris or tailings.

* NB: Cement kilns in the US are the third largest source of dioxin contamination of the environment. This is in part because kiln operators are allowed to incinerate intractable toxic wastes as fuel.)

CEMENT BLOCKS 1

Cement blocks provide one of the cheapest available means of erecting masonry walls. (See also Cement, above.)

CHLORINE

Chlorine is not a building material in its own right, but is commonly used in the manufacture of many common household items such as pesticides, bleaches, paper, nylon, dyes, pharmaceuticals and the ubiquitous PVC (polyvinyl chloride) plastics. Chlorine is a major source of dioxin, one of the most toxic chemicals the world has ever known. Dioxin is known to cause cancers, and foetal, reproductive and immune system damage.

(See also Plastics)

CLAY 1

Clay is used in house-bricks, mud bricks, rammed earth, pise, and terracotta roof, floor and wall tiles.

A type of clay called Bentonite is used as a sealing agent for ponds and dams, although it is rather expensive. (See also Gley, below)

(See also Adobe, and Natural Concretes)

COB

'Cob' comes from an Old English word meaning "a lump, or rounded mass". Cob builders use their hands and feet to form lumps of earth mixed with sand and straw. It is said to be easy to learn and and an inexpensive way to build, and apparently surpasses related techniques such as adobe, pise and compressed earth bricks, etc. Because there are no forms, ramming, cement or rectilinear bricks, cob lends itself to organic shapes - curved walls, arches and vaults. Earthen houses are cool in summer and warm in winter.

(See also Earth, Mud and Rammed Earth, below. See the article Building with Cob)

COLD FUSION

(See the Coming Energy Revolution in the Directory, and Zero Point Energy, below)

COMPRESSED EARTH BRICKS

Compressed earth bricks are like blocks of reconstituted sandstone. They are comprised of clay, sand and clay loam milled and mixed with cement. They are very energy-efficient to manufacture, requiring only about one-quarter to one-third of the energy needed for clay bricks, concrete blocks or even sawn timber. They are extremely strong, durable, and are recyclable. In Australia and elsewhere, the CINVA Ram is one of the most commonly used earth compression machines.

(See also Earth and Mudbricks)

CONCRETE 1

Concrete is used for floors, concrete block walls, piles and columns. It is recommended in place of stumps, for foundations and other inground applications, but only where timber is not suitable. The manufacture of cement produces greenhouse gases, and concrete aggregates are obtained by extensive quarrying operations. The longevity of concrete structures could make it an ethically acceptable choice in the long term.

Concrete is recyclable as low-strength concrete or roadbase. The CSIRO is investigating improvement of the compressive strength of reconstituted concrete, ie to make it more efficient and versatile as a recycled material.

(See also Aerated Concrete and Cement, above; see Slag, below, and the reference in Steel to drawbacks of steel-reinforced concrete. For info on bamboo-reinforced concrete, see Books, Bamboo in the Directory. See also Building with Concrete - the Hard Facts!, in Books, Building - General, and The Concrete Solution, in Grass Roots no. 114, May '96.)

COPPER

Copper gets a mention here because it has yet to be replaced as an efficient plumbing material for water and gas. Many other materials should not be considered for plumbing in our homes, offices and factories: this includes plastic, especially PVC. The growth of bacteria in water is inhibited by copper piping, yet can do so easily in certain types of plastic. The Olympic Village for the 2000 Games will have copper plumbing, not plastic.

Admittedly, copper is a non-renewable resource; but it is easily recyclable, and in fact a large proportion of the used metal gets melted down and reprocessed.

CORK

Cork* comes from the bark of Cork Oak trees (Quercus suber), which are grown mainly in Algeria, Spain, Portugal and other parts of the Mediterranean. It is actually an elastic, homogenous mass of flattened dead cells combined with a fatty substance which makes it almost impermeable to moisture and gases. About every 8-10 years, the bark can be carefully stripped from the trees without injuring them. Cork trees in fact live about 150 years despite the periodical harvesting. The best, close-grained cork comes from the more mature trees. During processing, the stripped bark is briefly seasoned and then boiled to make it spongy and pliable.

Cork is great for wine bottle stoppers and has been used for this purpose since glass was popularised in the 16th century. Nowadays, synthetic stoppering materials are beginning to make inroads on its dominance, due in part to a steady increase in its price on the world market. Cork's flotation properties have seen it used for fishing floats and lifebelts, etc, for many years as well. It also found favour for a time as shoe insoles, but again has been largely superseded by high-tech urethane foams, 'gels', and plastics. Cork is still in demand for noticeboards and pottery bungs, however.

In building, cork is best known as a great flooring material - in tiles and sheets or in lino - due to its slight springiness underfoot. It has a natural honeycomb structure because of the cavities formed during its growth on the tree. These air-pockets allow it to slightly 'give' when pressure is applied and also give it excellent heat and sound insulating properties (in the U.S., it is sold as ceiling insulation, with an 'R' value of 3.45 per 3 cm). Homemakers have tended to favour cork as much as synthetic alternatives because of its natural character and appeal.

(For suppliers and installers of cork, look in your local Yellow Pages under 'Cork Merchants' and 'Floor Coverings'.)

*'Cork' can refer to any light and porous or soft and spongy tree bark; such species as Erythrina vespertilio, and Duboisia can also be considered to be 'corkwoods'.

DRIFTWOOD

Thought we'd sneak this one in here ­ just because driftwood is almost like timber that didn't come from trees. In the upcoming new book Homework, by the publishers of the famous Shelter books, a beautiful driftwood house is pictured which comfortably housed a young American family with 3 children for a year in the late sixties (before the local 'authorities' burned it down).

DUNG

Cow dung when gathered fresh and made into a paste or plaster type render dries rock hard when applied to a timber or stone wall, etc. Dung houses are still common in India, for example, among the people living a more traditional lifestyle.

EARTH 1

Earth is the simplest, cheapest, most easily worked, durable and most ancient building material. It is the best thermal and acoustic insulator, and is flame, rot and insect resistant. Earth walls breathe and help create stable indoor microclimates. Earth can be used raw or fired or baked as bricks. Mud brick or adobe dwellings can last for centuries. Ancient cob and 'wattle and daub' type structures still exist in the UK and Europe, hidden behind modern brick and plaster facades. Earth building has also traditionally been a great medium for experimentation in form and colour.

Architects now talk about earth-integrated buildings of varying degrees. These can be either above or partially below ground level, and with accompanying passive-solar design features. Earth can be piled against walls and up to the eaves of a conventionally constructed dwelling to give maximum insulation. Purpose-built homes can be designed to be completely covered with earth (apart from access for people, air and light), if the temperature range is extreme. An earth-sheltered house with a turf roof and (mud) slab floor provides a good, year-round comfort zone. Pressed earth blocks make an excellent construction medium, as do cob and rammed earth walls.

Leichtlehmbau or 'light earth method', is a newly arrived technique in the West, derived from an old European tradition of building light earthen dwellings. LEM, as it is called, is becoming popular in New Zealand. There are no known practitioners in Australia, yet.

The University of Minnesota's Civil and Mining Engineering Building actually goes 7 storeys into the earth instead of upward, placing 95 percent of the building below ground. A periscope system provides picture-window type views of the campus at ground level, and a series of mirrors provides solar lighting for all the below-ground classrooms and offices. Groundwater is pumped up to provide cooling for rooms at ground level.

One potential drawback for earth is its vulnerability to water and impacts. These are remediable characteristics, however.

(See also Cob, above, and Rammed Earth, below. See Builders, Earth, Adobe... in the Directory).

EXPLODED SHALE 1

(Shale: Rock or laminated structure formed by the consolidation of clay or claylike material)

FERROUS CEMENT 1

An excellent choice because of its durability, and because it reduces the mass of materials in a structure. 'Ferrocement' as it is sometimes called, is really a form of reinforced concrete made of wire mesh, sand, water and cement, which possesses unique qualities of strength and serviceability. It can be used in construction with a minimum of skilled labour and utilises readily available materials. Proven as suitable for boatbuilding, it has many other tested or potential applications in agriculture, industry and housing. Ferrocement can be fabricated into almost any shape, is more durable than most types of timber and can be used as a subsititute for either timber or steel in many applications. Ferrocement structures don't need heavy plant or machinery for their manufacture - the process is instead labour-intensive.

(See back issues 48 and 49 of Earth Garden Magazine ­ Ferrocement Tank; Ferrocement Roofs.)

FIBRE CEMENT

Fibre cement is used in irrigation, plumbing, electrical conduits, columns, etc. Fibre cement board is made of calcium silicate, silica and cellulose. This is a fairly benign building material. It is suggested that only (non-toxic) surface coatings which allow the board to 'breathe' are used.

For fibre cement roofing (ie, not asbestos cement), a durable coating is required such as non-toxic cement paint.

FIBREGLASS

Fibreglass in the form of 'batts' (also known as bonded glasswool, glass fibre, glasswool, fibreglass insulation or batts, insulation wool, etc), is made of borosilicate glass, heat-cured phenol-formaldehyde resin and solvent-refined mineral oil. It is known to cause such adverse health effects as skin rashes and eye, nose, lung and throat irritation; it has also been looked at as a possible carcinogen and is being compared to asbestos in terms of its danger to human health. For these reasons, it is not recommended for insulation in any building. Where it has already been installed, it may be wiser to leave it in place IF it is residing safely behind gyprock or plasterboard, etc, rather than risk being exposed to it during removal.

One notable example of building with solid fibreglass panelling (ie, not fibrous) has been its use in bioshelter domes built by the New Alchemists in Massachusetts, USA. For these they used "two layers of translucent fibreglass, three quarters of an inch apart, which formed a thermal pane and functioned as a protective membrane for the system."

A Japanese farm equipment maker, Kubota, is involved in a project to recycle waste fibreglass. Their researchers are developing a method of separating it from the surrounding plastic, and plan to use it in the manufacture of building materials.

(See also Geodesic Domes, below)

FIBRE-REINFORCED THERMOPLASTICS

Fibre-reinforced thermoplastics are comprised of plastic and natural fibres, but which are cheaper and structurally superior to conventional moulded plastics, and are easily recyclable.

Fibres used can include: coir, jute, kenaf, flax, agave, sisal, bagasse, wood, rice hulls, henequen, sun-hemp, ramie, straw (rice, wheat, barley, etc).

Thermoplastics include: polypropylene, low-density polyethylene, high-density polyethylene, polystryren.

Applications include: automobile interiors, shipping pallets, decking and fencing, office products, furniture, storage containers (buckets, crates), window and picture frames, service trays, fan housings and blades, flower pots, etc.

Environmentally, FRTs are an undoubted improvement to plastic-only materials, because of the renewable fibre component and overall reduced energy costs during manufacture. Issues related to outgassing are unknown to this Guide as yet. With further foresight and research a vegetable plastic could take the place of the petroleum-derived components.

(See also Plastics)

FLAX (and LINSEED)

Flax is best known for its processing as linen yarn and fabric. However it is also used in lino, ropes, wallpaper, padding, chipboard, doors, tiles, and insulation materials.

Linseed oil, which is obtained by pressing the seed of the flax plant is used in paints, lacquers, varnishes, dry mortar, plaster, and printing inks.

FOAM

In the context of building and construction, foam is a generic term for any materials which have been permeated with bubbles of a gas. As such, it is mainly used for cushioning and building insulation.

Foam rubber, for example is traditionally latex rubber which has been whipped to make it frothy prior to being vulcanised (ie, treated with sulphur and heat). Synthetic or plastic foam (or styrofoam) is made from a polymer of the styrene. Commercial versions of these synthetic materials are notorious for outgassing formaldehyde which is used during their manufacture. Formaldehyde-related diseases include cancer, dermatitis, asthma. Another by-product of the breakdown of styrene is styrene oxide, which is can cause cancer, or liver and kidney damage. Many if not most synthetic PVC foams are loaded with toxins and should be considered too dangerous to recycle.

A non-toxic insulating foam called 'Air-Krete', is now marketed in the U.S. as an alternative to fibreglass insulation. Air-Krete is made from tiny magnesium oxide bubbles which encapsulate atmospheric air. Magnesium oxide is a natural mineral used for centuries to make fire bricks. Its higher cost is offset by its superior thermal qualities.

Non-toxic foams based on vegetable plastics may be possible.

GEODESIC DOMES

Geodesic domes, the sixties brainchild of R. Buckminster Fuller, have slowly made their way into the mainstream of architecture. Their geometric design allows them to enclose substantial spaces with minimal structural materials.

One example developed by the New Alchemists in the U.S. is termed the Pillow Dome. It comprises less than 4% framing on its surface, compared to 10­25% for most greenhouses. The 9 metre dome weighs about 270 kg. Its plastic triangular panels are heat-sealed at the edges, clamped to the geodesic framing and then permanently inflated with argon. This prevents wind-flap and condensation inside the pillows while making pockets of still gas for insulation. The inflated panels pre-stress the building and give it the rigidity to withstand winds over 160 kmh.

The dome's pillow panels are inflated with dry argon gas, an inert noble gas commonly available through welding suppliers. Argon loses less heat through conduction and convection than air.

The Plastic glazing is a Dupont-manufactured product called Tefzel, three layers of which transmit as much sunlight as one layer of glass ­ about 85%. Tefzel is non-toxic, chemically inert, and long-lived. It is one of the few plastics that transmits ultraviolet light ­ and which helps to prevent the growth of fungal diseases on plants growing inside the dome ­ yet blocks much of the long-wave infrared radiation, thus reducing potential heat-loss.

Twelve fibreglas silos, each of approx 2 cubic metres capacity, are placed inside the dome to give it thermal stability.

GEOTECTURE 1

Geotecture refers to the design and construction of earth covered and earth sheltered housing. (See Clay, Cob, Earth, Mud, Natural Concrete, Pise, Rammed Earth, Soil Cement, Turf, Wattle and Daub).

GLASS

Glass is that ubiquitous, seemingly invisible barrier used in windows, doors, skylights, etc, of most Western homes. Like most manufactured products, it places a certain amount of strain on the environment during manufacture. The heat required for the process of fusion of the silica (sand), sodium oxide, and calcium oxide (limestone - because of its alkalinity) with mineral oxides, colorants and broken glass (cullet) matter (sand) is quite considerable. Once in-situ, however, glass is relatively inert, long-lived and efficient at its task.

In the US, recycled glass is being incorporated into 'Syndecrete' cementitious floor tiles. Also, a Seattle company, Trivitro, converts recycled glass into an abrasive material suited for sandblasting which offers environmental and health benefits over traditional sandblasting minerals since it doesn't have crystalline silica or heavy metals in its makeup.

Look for salvaged windows at your timber recycler. If it's available and affordable, always opt for safety glass (ie, intact panes which have been either tempered or have layers of plastic or mesh to prevent disintegration). If you must buy new glass, check out energy-efficient ones such as Pilkington Smart Glass (see Building Materials, Non Timber, in the Directory).

GLASS BRICKS

Light-conducting glass bricks have been available through building suppliers for many years. Also, old bottles and flagons set in walls reduce the amounts of concrete or cement required, yet make ideal light-conductors and maintain privacy.

GLEY

Related to the word 'glaze', a gley is like a biological plastic membrane such as is found in bogs, which is formed by a bacterial process that requires anaerobic conditions.

Traditionally a technique for sealing ponds and dams, there is potential for the process to be adapted for human-made structures. The Russian-devised version for dams uses a slurry of animal waste (pig manure) applied over the inner base and walls of the dam in multiple, thin layers, which is then itself covered with vegetable organic matter such as grass, leaves, waste paper, cardboard, etc. This is all then given a final layer of soil which is tamped down and the mixture is left for several weeks to allow the (anaerobic) bacteria to complete their task, at which time the dam is ready for flooding.

Gleys have the potential to revolutionise water storage capacity in regions with hightly porous soils. An aquaculture industry in otherwise unsuitable areas scould be one of the benefits of this technique.

Unlike bentonite clay, gley materials are virtually cost-free and are comprised of 'wastes' which would normally be discarded in the normal course of operations. Also, plastic and rubber dam liners may actually be dependent on the same anaerobic process for their own continued effectiveness rather than their lack of holes or punctures ­ ie, it is the anaerobic layer created below them rather than their own membranous qualities which prevent water seepage in the long term.

'GRANITE' 1

An artificial granite is available, called Environ Biocomposite. It has the look and feel of granite but is half the weight, is workable like wood and is non-flammable. It is made from a mixture of recycled paper products, plant-based resins (soy flour by-product) and colourants. It is all non-toxic, including having zero formaldehyde content.

GRASSES

Mainly used for thatching, but grasses can also be used like straw in under-roof insulation. Vetiver grass, for example, is traditionally used for weaving window-shades, which, when moistened, give off a delightful fragrance. Grasses often provide an abundant raw material for walls, roofs and ceilings, etc, in areas which lack sufficient trees due to climatic or ecological reasons. European architects of the biological building school are beginning to reintroduce grass roofs.

Spinifex grass is a traditional material used by indigenous people on their dome-shaped shelters in north-west Western Australia. The grass tree (Xanthorrhoea) provided indigenous and the first non-indigenous Australians alike with durable thatching material.

In Africa's arid Sahel region, people move from their mudbrick homes into shady mat-tents to escape the intense heat (40­45°C). The rectangular mats which 'tile' the roofs are often woven from grasses (but may be made of palms or rushes).

The Fijian bure is comprised of a bush timber frame with a thatched roof of grass or reeds, and grass or palm matting walls.

Australia's many species of Sedge grasses which grow in fresh and saltwater marshes may have great potential for home building - either thatched and woven for roofs and floors, or tied in thick strong bundles to form walls and columns.

(See also Reeds, Palms and Seagrass.)

GRASS SOD

(See Turf, below)

GYPROCK 1

(See Plaster and Plasterboard)

GYPSUM 1

Gypsum is comprised of hydrated calcium sulphate; it forms the base for Plaster of Paris. More commonly these days it is used in plasterboard (Gyprock) for roofing, wall lining and flooring, etc.

HAIR

Animal hair has been used for shelter construction by the nomadic tribespeople for many centuries, perhaps millenia. The Bedouins and Berber tribes respectively have used camel hair and goat hair taken from their herd animals, presumably for both shelter and warmth.

HEMP

Thought to have originated in the area just north of the Himalaya mountains, the hemp plant was used by the Chinese to produce fibre as early as 2800 BC. By 500 AD the plant had spread to Europe, and eventually it was brought to the New World by the explorers. Now it is a common plant found wild or cultivated over much of the world.

There are thirteen broad categories (and upwards of 25,000 specific applications) for industrial hemp: textiles; cordage; construction products; paper and packaging; furniture; electrical; automotive; paints and sealants; plastics and polymers; lubricants and fuel; energy and biomass; compost; food and feed.

Henry Ford used hemp, wheat, straw and synthetic plastic for the fenders and hemp and other agricultural materials in the fuel of his early prototype Ford automobiles.

Hemp-based construction products* can be used in place of cement, timber, gyprock, plaster, insulation and acoustic tiles. Washington State University's Wood Composite Laboratory has tested hemp for use as medium density fibreboard. It found that hemp is twice as strong as wood.

French, German, Hungarian, Polish and US companies now make hemp-based construction and insulation products**. Many other countries grow the raw material and/or manufacture hemp paper, and could adapt to more diverse production when demand is sufficient.

French-made products use natural lime and water for binding agents. Processed hemp can be used as cement and poured directly onto soil. Unlike cement, the hemp-based product is very flexible, doesn't crack, is water-resistant, and seven times lighter than concrete. These overseas-made products will begin to command greater attention in the Australian marketplace.

Hemp-based paints have already proved their superior coating and durability characteristics, but the cost of the oil will prevent any mass marketing of them until political climate allows widespread cultivation.

Surfboard makers in Sydney and Byron Bay are making fibreglass-free surfboards, which are instead sheathed in a knitted hemp fabric, sourced from Eastern Europe, Nepal and China, and knitted in Melbourne. The surfboards also have biodegradable polystyrene cores and biodegradable resins which have minimal environmental effect when they break down (although they are still toxic materials ­ research into hemp surfboard blanks and glues continues...). With more than 80,000 surfboards built annually and enormous health hazards associated with traditional surfboard manufacture, this is a great step ahead.

NSW finally has had trials of industrial-grade hemp fibre crops: the first was grown (not very successfully) near Armidale and was overseen by the University of New England.

If there is any justice, once the issue of growing low THC hemp*** is resolved, we can look forward to seeing an ever-increasing amount of real Aussie industrial hemp being converted to paper, fabric and construction material. The NSW Dept of Agriculture wants people interested in establishing further trial plots to contact their head office in Orange.

* For more info, see chapter 3 of the booklet Industrial Hemp, titled Hemp's 25,000 Practical Products

** See the article Building with Hemp, and the listings under Building Materials, Hemp, Hemp Organisations and Books, Hemp, in the Directory.

*** Industrial hemp is allowed only a low tetra hydra-cannabinol (THC) content; there was strict security and stringent testing of the Armidale crop to make sure that the hemp did not exceed the allowed percentage of THC. (Those in the know say that the THC content of cultivated hemp will steadily increase with each successive generation, anyway.)

HESSIAN

It was not uncommon for rural houses in South Australia in the last century to be made out of wheat bags stretched over wooden frames and painted with a mixture of lime and cement.

Hessian was also used for the walls of the famous Coolgardie Safe. The sides of the safe were kept wet by filling a water container at the top and letting it overflow; the evaporation of water from the hessian kept the inside cool.

HOLLOW TREES AND LOGS

Many photos survive of early European immigrants and victims of the Depression making homes in large hollow logs or tree stumps. In the forests of century ago, it was not uncommon to find trees which measured more than a man's height in their diameter.

In Victoria's Gippsland, the upper part of big hollow trees were sawn off and a roof put on. Sometimes there was room for two or three floors to be built inside the trunk, with small windows cut out here and there. Such dwellings later became kitchens, stables, stores, or poultry houses, once their human occupants could afford a 'proper' house.

ICE and SNOW

Frozen water - as ice or packed snow - makes for a great igloo. Many such shelters have been built in the Snowy Mountains region of NSW, the Victorian Alps and Tasmania.

IRON

Mainly superseded by steel, which is an alloy of iron and carbon. Portable iron houses were being advertised in the 1800s as 'suitable for Squatters, Farmers, Selectors, Diggers, and others'.

LIME

Base ingredient for lime plaster and Portland cement.

LIMESTONE

Limestone is said to be equivalent in price to sandstone, but is considerably cheaper to lay in walls due to ease of cutting. A quarry exists at Mt Gambier in South Australia, but this is rather remote for NSW builders. Quarried materials are also quite energy-intensive when compared to recycled brick, stone or mud brick, etc.

LINSEED

(See Flax)

MAGNESITE

Magnesite is a composite of cement, magnesium carbonate, sawdust and sand ­ used as a hard, continuous floor finish. It is not so common in Australia.

(See also Sawment)

METALS

A non-renewable resource - very precious; use sparingly. Apart from scrupulously reusing and recycling your own metal containers, appliances, furniture, etc, it is important to seek out recycled or salvaged metal building components whenever possible. Steel, copper and aluminium for example, are definite candidates for continuous reuse. Everything from nails to corrugated roofing to piping to wall and structural brackets, window frames, steel beams, wiring and cable can be kept in the building cycle and not ejected as waste unless rust, corrosion or inordinate stress or damage have deprived the metal of its functionality.

During the Depression, homeless people squatted on land near West Melbourne's Dudley Street rubbish tip, and built themselves homes (the Dudley Mansions) out of salvaged scrap metal from the tip.

If new materials must be used, buy only those which will be durable and/or fixable.

Metal furniture is useful for its hypoallergenic properties, but metal fittings in a dwelling (including pipes, wiring, cabling, ducting, bedsprings, furniture, steel frames, metal roofing, etc) may also disrupt natural electromagnetic fields, to the detriment of human health. (NB: Digital mobile phone users who wear metal frame glasses are apparently more likely to suffer from the adverse effects of their phone's microwave radiation.)

MUD1

Dwellings in Turkish villages of 8,000 years ago were made of wood, reeds, stone and/or mud bricks coated in a render of mud or lime-based plaster bound with chopped straw, animal hairs, feathers, or cow manure.

MUD BRICK 1

Mud bricks, stabilised with lime, cement or bitumen and mixed with straw are used to build low cost, energy-efficient, durable dwellings the world over.

(Refer to Grass Roots Magazine, issue 113 - A Mud Brick Vision, and, Obtaining a Mud Brick Building Permit - see Books, Journals, in the Directory.)

NAILS

Iron, steel, copper, brass, nickel and alloy nails are straightenable, reusable and recyclable. (Nails have been made from very hard, durable timbers in the past - especially in areas where metal corrosion is likely.)

NATURAL CONCRETES & CLAY PANS 1

Several types of concretions or cemented particles occur naturally in soils, depending on mineral type. Calcrete forms naturally in certain types of calcium/phosphate-rich soils. It is extremely hard and is impervious to tree roots, but when broken up, can be used as a very stable building material. Underground homes in the US have used the naturally-occuring surface layer of calcrete (or caliche) for their roofs. Other natural concretions are: silcrete, ferricrete, solcrete and clay/plough pan.

NUTSHELLS

A Spanish company has developed a wood subsitute material called Maderon which is derived from almond, walnut and hazelnut shells. The shells are crushed into a powder and mixed with a resin, creating a paste which can then be moulded with adapted injection moulding technology to make furniture items. Maderon is itself recyclable.

PALMS

Palm fronds are some of the most abundantly found base materials for roof thatching, being used all through Southeast Asia and the Pacific, Caribbean and Indian Ocean regions and northern Australia. The combination of the leaves and an efficient overlapping method of fixing means thatched roofs of cabbage palm for example, can withstand torrential tropical downpours as well as protect occupants from the heat of the sun. Durability varies according to climate and aspect, but generally well thatched roofs could be expected to last for 5 - 10 years before requiring replacement. (Of course, when food supplies ran low, Australian indigenous people often moved to another area ­ and another easily erected but serviceable dwelling.)

In Australia, the coastal Pandanus and tropical Coconut Palms' long, straplike leaves are ideal local sources of thatching material. Balinese Ubud Palm leaves are being imported by a Brisbane supplier, and are available in Sydney from roof thatchers Gilbert Thatch.

Coconut fronds when split along the midrib make excellent (biodegradable) wall panels and screens.

(See also Reeds and Grasses).

PALM WOOD

Coconut palm wood is quite useful in many building applications normally requiring timber. A sydney company, Pacific Green, imports and manufactures furniture made from plantation-sourced Fijian coconut palm wood.

See also Tropical Plantation Timbers.

PAPER

A German company, WS Handelsund *, manufactures coffins weighing only 12kg, made from 85% waste paper and which pack flat. They cost half the price of a wooden coffin, yet their appearance and functionality is very similar. The manufacturer claims a number of environmental benefits for their product, including reduced air pollution during cremation. (If the Australia-wide hemp trials are a success this year, we may even get to see Australian-made hemp coffins.)

* See under Non-Timber Building Materials in the Directory.

PAPIER MACHE

Papier Mache has been used as cellulose insulation for many centuries in France cellulose effectively being pulverised paper. When treated with non-toxic borax decahydrate, the material becomes fire resistant.

PERLITE

Perlite is an excellent insulating material. It is mined from volcanic ash which is crushed to size and them expanded in a furnace to form the tiny lightweight 'pebbles'. When poured into concrete blocks, perlite increased the 'R' value from 2.86 to 9.07.

PISE 1

Pisé, or Pneumatically Impacted Stabilized Earth, is much like rammed earth, except that the material used may be comprised of clay and/or gravel. Pise walls are nice and thick, and have the strength of more conventional walls. They can be textured and coloured to taste.

Early European settlers in South Australia ­ with insufficient timber available and too little funds for stone-built houses ­ found well constructed pisé dwellings to be cheap to build, and very comfortable and durable.

(See also Cob, Earth, Rammed Earth)

PLANT FIBRE

(See also Vegetable Fibre, Hemp, and Cellulose)

PLASTER

Plaster when wet is essentially a soft, 'plastic' mixture; it is usually comprised of lime (heated, ground gypsum plus water), sand and hair, and is spread on walls to form a smooth surface suitable for painting.

Plaster of Paris is comprised of calcium sulfate and is a potential eye and respiratory system irritant. An approved dust respirator should be worn when working with anything larger than minute amounts. If lime is added to the plaster mix, this can make it even more hazardous. Plaster of Paris can cause serious burns if spilled on the skin and not washed off immediately.

PLASTERBOARD 1

Plasterboard is comprised of a gypsum plaster core with a paper lining. In general, this is a good choice for building because it breathes ­ provided that any accompanying chemicals are checked for outgassing. If the board has been manufactured overseas, the likelihood increases that it may have been manufactured with talc or mica and thus may be emitting radon gas and gamma radiation. Note: natural gypsum is not normally radioactive.

Choose those boards which have no synthetic chemicals in their makeup, and little or no glass filament. Look for a non-chemical means of fixing and finishing plasterboard.

PLASTICS (Avoid PVC! Use non-synthetic materials, or PVC-free Polypropylene or Polybutylene instead)

Plastics function quite well in inground applications, or where materials are likely to be exposed to persistent damp, bacteria, or poor ventilation. They are also used for mouldings, insulation and durable facings on board products.

However, the Guide recommends that you opt for more environmentally friendly materials whenever possible. Plastics are made from non-renewable petroleum byproducts, are energy-intensive to produce, involve the use of toxic chemicals and create toxic waste during their manufacture. Most plastics are not biodegradable, making for an ever-growing dilemma of how to safely and ethically dispose of them. (Scientists have yet to devise a viable plastic-eating bacteria.) Too much plastic is abandoned in landfills after only one use - as take away food containers, plastic bags, packaging material, etc. Countless land and marine animals die every day after being choked, strangled or poisoned by plastic rubbish - plastic bags, bread tags, six-pack rings, plastic foam, etc. Plastic refuse is also an horrific visual pollutant in the urban and rural areas and marine environments of the world. (Customers at burger restaurants and takeaways are mostly unaware of the fact that they are paying for the plastic packaging which all too briefly holds their fast food before being discarded and all-too-often blowing away into the ecosystem.)

Plastics don't 'breathe' like natural materials (wood, stone, earth, cotton, hemp, etc) and in fact often emit noxious fumes or hormone-disrupting, biologically active chemicals (phthalates, dioxins) - such as from PVC products, or when they are burnt (highly dangerous).

Products which contain the organochlorine PVC include: pipes, guttering, windows, vinyl flooring, wallcoverings, shower curtains, blinds, non carbonated drink bottles, cooking oil bottles, cling film, margarine tubs and boxes, interior trim, sealants and underseal in cars, tubing, probes, catheters, blood bags and gloves in hospitals.

Greenpeace*, which argues that 99% of current PVC products have a safer alternative, has been fighting long and hard to prevent the use of PVC plastic building materials in the construction of the Sydney Olympic Village. Unfortunately, Australians rank second to Americans in their consumption of PVC products. Recent (and hopefully short-lived) comebacks for PVC have seen it featuring in designer clothing and inflatable designer furniture. Chemicals used to manufacture PVC include the persistent and toxic organochlorine group of chemicals. Production also creates highly dangerous dioxins and hexachlorobenzene (HCB) as waste products. Additives during manufacture include lead and DEHP, both highly poisonous. Pthalates added to PVC are suspected carcinogens.

Older plastic water pipes release pseudo-oestrogens into the water supply. These are implicated in the ever-decreasing sperm counts and increasing feminisation of male animals and humans worldwide.

The U.S. Consumer product Safety commission warns that 'miniblinds', which are made in China, Taiwan, Mexico and Indonesia contain PVC, which degrades to lead dust after being exposed to sunlight and heat. Lead is added during production in order to stabilise the plastic materials in the blinds. Young children have been found with high lead levels in their blood due to ingesting dust from the miniblinds. Horrendous health problems have ensued, including mental and physical retardation and kidney failure. Sweden, Germany and Austria have banned the use of PVC in construction and other applications.

Plastic-based (petrochemical) paints don't allow vapour-exchange in timber, which can lead to its premature breakdown - the exact opposite of what is desired.

Recycling of plastic is very energy-intensive, polluting, and is only third best in terms of a program to "reduce, reuse, recycle". Yet many more recycled plastic products are coming on the market. Those plactics which best lend themselves to recycling are polypropylene, polystyrene, polyurethane, polyethylene (PET, HDPE). Also perspex, polycarbonate and ABS plastics can be recycled. (Processors of all these can be found in the NSW EPA's Recycling Directory).

Polymer Corp. of Queensland has developed a process which fuses and laminates mixed, recycled plastics making them suitable for use as a wallboard (the Guide is not aware of the degree of outgassing from this product, however). Their innovation is that they have managed to devise a technique which can utilise different kinds of plastics. This has been a challenge for the recycling industry because it has been extremely difficult to reprocess plastics with different characteristics, and it has been very hard to get clean, single-type used plastics from the waste-stream.

In Holland, countless thousand of recycled plastic coffee cups, bottles and yoghurt containers were melted down and remoulded to make 50 metre-high, earth-filled noise barriers which were placed alongside a railway line. It was apparently an easy material to work with and also competes well with concrete and steel barriers in terms of price**.

The Japanese car maker, Honda, has opted to establish a new company to manufacture new items, including tables, chairs and simulated wood flooring - all with plastic left over from car production. Also in Japan, a lingerie maker has developed a new line of women's underwear - made from soft cloth and lace produced from chemically processed fibres of crushed plastic bottles. American and European outdoor clothing manufacturers have been using recycled plastic fibre for some time to make thermal clothing.

The U.S. organisation, Rainforest Relief***, is promoting the use of post-consumer recycled plastic lumber for waterfront construction ie, piers, wharves, pontoons, and above-water applications. They believe it to be an excellent way of reducing consumption of rainforest timber. It is longer lasting and therefore more economical than wood and other materials, which is important for government budgets. It can be recycled again after use, and does not leach chemicals.

Non-PVC and non-petroleum-based bioplastics and vegetable plastics are being developed by scientists and these are slowly finding their way onto the market as their cost of production decreases, although nature has already developed such things****.

(See also Fibre Reinforced Thermoplastics)

* See under Chemicals, Toxics Groups in the Directory.

** More info: Municipality of Tilburg, P.O. Box 90155, 5000 LH Tilburg, Holland. ph: 0011 31 13 428811.

*** See under Forest Activist Groups in the Directory.

**** See Gley and Hemp, above. See also under Non Timber Building Materials, in the Alternative Directory.

PLEACHING

Living Walls: The Grown Environment

Architectural Pleaching is the process of creating a living bond between growing trees of the same or similar species - a kind of grafting to create one organism from two plants, but with two or more individual root systems. Many species, including eucalypts such as the Australian River Red Gum, are actually self-grafting (ie, are 'inosculate' - from the Latin, osculor, to kiss). The curtain fig tree also relies upon intergrafting of twining for its survival. The roots of such trees also form underground pleached networks. There could be many more which self-graft or respond to cultivated grafts. Low-growing or dwarf species could be pleached to produce living fences - suitable for paddocks and for insulation barriers near dwellings.

At the recent World Bamboo Conference in Bali, a shadehouse made from still-growing trees, was demonstrated to delegates . In this case, leguminous nitrogen-fixing trees had been set at the four corners of the intended shadehouse structure. Their trunks had been cut part of the way through at about 2 metres above the ground and the upper part bent down horizontally and interlaced with the other sections. A shadehouse roof had then been made from interwoven bamboo culms, which kept the structure solid and in place.

The early hedgerows of Britain were made through an ancient process of grafting together branches from adjacent, individual bushes - ie, pleaching them - which meant that one large, living organism was created out of many smaller entities. Up to the 17th century, pleaching was considered an art form in England, producing many pagodas, tree houses, and summer houses. The technique was also used in Mediaeval Europe to construct shelters and dwellings from whole grids or 'orchards' of pleached trees. When the trees were mature, their pleached branches formed the level base of a platform which elevated the community above the frequent floodwaters while branches of outer trees were grown up to form the walls and roof.

(See the articles Pleaching and Living Fences. See also Biotecture, above. Early Permaculture Journals, no's 7 and 8, made mention of pleaching and biotecture. See also Earth Garden, issue #99.)

POLYCARBONATE

Sheets of Polycarbonate form a translucent roofing material for areas which need protection from the elements yet still require natural light. They make good surface skins on greenhouses. However, being a petroleum-based product, polycarbonate is quite energy-intensive to manufacture and therefore comes with some environmental cost. Polycarbonate is recyclable in NSW, but this also requires energy-intensive processes to accomplish.

Check with your local building materials supplier for good quality second hand sheets or look at the option of using translucent fibreglass instead. (Please don't purchase polycarbonate sheets from companies asssociated with the Mitsubishi Corporation - Mitsubishi continues to log rainforests throughout the world.)

(See under Non Timber Building Materials in the Directory)

POURED EARTH 1

(See Cob, Earth, or PISE, above, and/or Rammed Earth, below.)

PUMICE BLOCK

Pumice is a porous or spongy form of volcanic glass which is light in weight and floats in water but is dimensionally stable. It is best known in Australia for its abrasive qualities either as a small block used for hand-cleaning and textile conditioning, or in powdered form for industrial cleaning applications. Larger building blocks of pumice in Australia are not known by this Guide, but the material is plentiful on many of our coastal beaches.

PVC

(See under Plastics)

PVC-FREE SYNTHETICS

Three companies in Sydney, Heritage Contract Systems, Forbo Australia, and Regupol import non-pvc synthetic and natural rubber flooring.

One of the largest electrical cable companies in Australia, OLEX Cables, manufactures a new generation of PVC-free cables called Envirolex. Apart from placing far less stress on the environment during manfacture, the new cables are superior performers to PVC in fires, giving off less smoke and acid gas emissions, which significantly increases fire-safety levels in factories and offices, etc. PVC sheathed cables, on the other hand, can quickly decompose, giving off toxic hydrogen chloride fumes, which become hydrochloric acid when they contact moist areas on the human body eyes, nose, throat, lungs.

The Euro Tunnel, London Underground rail system, and the latest P&O cruise liner all have zero PVC used in any construction materials or fittings. It is to be hoped that the Sydney Olympic Games Committee will stick to its word and not allow PVC to be used in any sporting venues or living quarters.

(See Plastics, above, and Non-Timber Building Materials in the Alternative Directory).

RAMMED EARTH 1

Rammed earth building (sometimes also called either Poured Earth, &/or PISE), requires the use of minimal amounts of timber and maximum amounts of onsite (free!) raw material, ie soil. It is a viable, resource- and energy-efficient option: rammed earth is one of the least labour-intensive of the earth building modes and requires little maintenance. For these reasons, its popularity is continuing to grow.

The rammed earth technique's viability is site-dependent, however, as many soils are not compatible, and because the cost of importing appropriate soil is economically and environmentally expensive. It is important to test soils for compatibility before attempting this means. Cement may be added to sandy soils to improve strength and stability; clay soils are often strong enough without cement. Rammed earth floors and walls have excellent insulation properties. Construction is effected by means of pouring and/or packing earth into timber forms and building up sections of wall, then removing the forms when the new sections of wall are sufficiently dry. Any imperfections, cracks, or damage are easily fixable with mud render. Constructing roofs with generous eaves to protect walls from the worst of the weather is always advisable.

(See Cob, Earth, PISE, above, and Sawment, below. See the article Rammed Earth - with a veneer of science. See Builders, Earth Adobe, and/or The Earth Garden Building Book, in the Directory.)

REEDS

Many indigenous peoples have for centuries built the roofs and walls of their dwellings - and even boats with reeds. Reeds are also woven as mats, baskets, ornaments, chair seats and broom bristles.

They are more than just a standby in areas lacking sufficient timber for building, they give great design, structural and energy-efficient qualities in their own right. Bundled and tied reeds can be used in a structural, load-bearing capacity.

Reclamation of wetlands for agriculture, use of chemical fertilisers and desertification in developing countries is putting many reed species on the endangered list. Holland is a producer of reeds for the thatched roofs of Europe, as are areas of Germany and the waterways of Norfolk in England. Taiwan and China are traditional producers of seagrass.

Early European settlers in rural Australia made thatched reed roofs with eucalyptus leaf linings for their sheds and dwellings.

The Thatched Earth Cafe at Heronswood in Victoria is one of the few contemporary Australian examples of a thatched reed roof. It was created by master thatcher Norbert Kleinschmidt. The organic curves of the roof's outline make it immensely aesthetically pleasing. It is a beautiful light brown colour and incredibly neat and trim.Although the installation cost was higher than for a 'traditional' corrugated iron roof, the life-expectancy is about 80 years. The inside temperature on a 40 degree day was 23 degrees, and was warm on cool days. The thatch is 250 mm thick and so densely packed that it does not allow rain to penetrate. Ceilings are optional. (See the article 'A Roof of Reeds' in Grass Roots No. 120, April/May '97).

NB: Avoid imported products made with pesticide-treated and/or synthetically coloured reeds.

(See also Grasses, Palms and Seagrass.)

ROCK 1

(See Stone)

ROCKWOOL

An insulating material consisting of wool-like fibres made from molten rock or slag by forcing a blast of steam through the liquid (Macquarie Dictionary).

RUBBER

Rubber appears mainly to be used for flooring in Australia. Several companies manufacture and/or import enviro-friendlier rubber-based floor coverings. (See also Tyres, below. See Non-Timber Building Materials in the Directory. NB: For info on availability of imported Indian Rubberwood, see under Timber Industry Promotion Groups, in the Directory)

RUBBLE 1

Also known as 'Slipform Stone building'.

(See back issues 9 & 42 of Earth Garden Magazine)

SAND

Sand is included in every mix of mortar, ferro cement, and concrete. It is one of the main ingredients of 'sawment' and soil cement (see below). In the US, it is being bagged and wired in layers to build very strong, stable structures.

(See the article Adobe & Super Block Technology).

SAWDUST

Used for heating fuel, makeshift floors, and weed-suppressing on garden paths. (See also Sawment, below.)

'SAWMENT' (Sawdust, Sand and Cement) 1

This is a building medium gaining acceptance in the Northern Rivers region of NSW and will no doubt be a strong contender for mainstream applications. A moist mixture of the three materials is packed into wall-cavities to provide thick, solid walls - a low cost way to get excellent insulation properties. Can be used either in construction or to retrofit an existing dwelling.

(See also the article Sawdust, Sand & Cement.)

SEAGRASS

In Australia, most often found in seagrass matting, although it has found application as a home insulation material.

(See also Grasses, Palms and Reeds)

SEWAGE SLUDGE (!)

Yes, believe it or not, you can get your poo together! A pilot plant is being set up by Wollongong University's Dept of Civil & Mining Engineering, where they will manufacture bricks made up of 70 percent sewage sludge. The bricks are odorless and are about 20 percent stronger and lighter than regular bricks. They are also more porous, which means they bond to the cement very str`ongly.

Clay and shale is added to the wet sludge and baked in an oven for several hours, producing a 2 kilo brick. Experimental production in the U.S. produced half a million bricks from 30 tonnes of sludge. Given that sludge disposal is very expensive for local governments ­ and often smelly and/or dangerous for citizens ­ actually making a buck out of making a brick must be very appealing once the squeamish feeling is overcome.

(See Innovative Civil Engineering Material from Sewage Sludge: Biocement And Its Use As Blended Cement Material, in Books ­ Non Timber Building)

SISAL

Sisal is a fibre derived from the Mexican agave plant. It is most commonly used in carpets, and is non-toxic, antistatic and antibacterial. Sisal's durability and environmental friendliness is making it increasingly it popular with Australian consumers.

SKIN

(See Animal Hides)

SLAG

Incinerator slag is made into paving stones and other building materials in Japan. The City of Omiya, Saitama is the first to use slag (20%) in asphalt being used on roads. A nearby region has halted its use of incinerator ash in paving stones because of community fears regarding hazardous materials (dioxin, heavy metals) in the ash. Residents raised concerns about the consequences of weathering and leaching of the toxic substances, and the danger potential for children playing on or near the blocks.

There is apparently a Japanese-developed process for combining slag with concrete waste to make very hard rocks.

SOD

(See Turf, below)

SOIL CEMENT 1

The compound of soil, cement and water, mixed in the proper proportions and compacted to the proper degree, constitutes 'soil cement'.

SOLAR-ELECTRIC ROOFING

A robust, high-efficiency solar panel is being marketed in Australia as a roofing material which also generates solar energy. The photovoltaic integrated roof panel comes in four styles: a flat roof style, one for a stepped roof, and two styles for a batten and seam roof design. A large Japanese eco home building company has already incorporated them into its designs. It is estimated that a 55 sq metre roof could generate sufficient energy for a family of four from an average of 3.5 hours of sunlight per day. (See Unisolar, under Alternative Energy Suppliers and Services in the Directory)

SOY BEANS

Soy bean flour is used to make Environ Biocomposite, a hardwood-like material with the appearance of granite. (See under Non Timber Building Materials, in the Directory).

SOY MILK CARTONS

Being a combination of paper, plastic and aluminium, soy milk cartons can be used as a lining material and/or reflective insulator in ceiling cavities.

Soy cartons also make great tree seedling containers, etc. Because of the high proportion of eucalypt pulp used in their manufacture, used soy cartons are now utilised as a component of high-quality recycled paper. However, re-using them is still the preferred option. In an ideal world, perhaps we would have only refillable soy and dairy milk containers...

NB: Very big multinational corporations like Coca Cola and Sanitarium control most of the world's soy milk market. They mostly use destructive flooding irrigation to grow the beans which eventually causes collapse of the soil structure. Monsanto corporation's genetically altered, Roundup-resistant* beans also mean higher levels of herbicide residues in your soy milk, making it not quite the environmentally-friendly option it would appear to be.

* See the info on Roundup (Glyphosate) in Toxic Herbicides.

STEEL

Steel is recommended as a substitute for many structural hardwood uses and is often cheaper to buy than its equivalent strength in timber. Steel can be added-to and has the advantage of speedy and precise construction; it is incredibly durable; it is also reusable and recyclable.

Steel reinforced concrete was in the past often used in large buildings. Sometimes, when the concrete began to weather and develop cracks, the steel rods would rust and expand up to 63 times their own volume. The concrete casing would then begin to break up, thus making prematurely obselete (and dangerous) a very expensive concrete building.

Industrialised building systems using steel components (beams, girders, rods, wires, cables, mesh, etc) are available and offer opportunities for innovative design.

Steel's main drawback is that its production consumes a lot of energy and adds to greenhouse gases, particularly carbon-dioxide. Also, according to a new book by Greenpeace, steelmakers are now cited as one of the worst dioxin polluters in Australia, accounting for more than 90% of total emissions in NSW, and having emissions of up to 65 times the German standard. (A Japanes researcher has apparently developed a high-purity oxidised steel-refining process, which will reduce greenhouse emissions considerably).

Steel still offers a reasonable alternative to unsustainably-harvested timber, but in terms of lifecycle energy requirements and emissions, unless it is recycled, is less desirable to recycled or (mixed species) plantation-grown timbers, which are renewable resources.

STONE 1

Stone, in its many varieties, is among the most practical, durable, and aesthetically-pleasing of building media - one of the cheapest too, if it is available onsite for construction. Quarried stone types such as sandstone, granite, slate, marble, basalt (also known as blue metal gravel, good for concreting, roads and paths), and river stones are all popular choices, although their price of some of them often limits their use to feature work. (Being non-renewable, quarried stone will continue to become ever-more expensive.) It should be noted that quarrying is essentially industrial mining, which makes especially the harder stones, such as granite and marble quite energy-intensive materials by the time they are on site (quarrying, handling, processing, storing, shipping, etc).

Although renowned for its durability, stone can be prone to splitting if exposed to water and/or temperature extremes.

Stone floors and walls can also create an inivisible hazard by introducing significant levels of radon1 gas into the home.

People who quarry or process stone must protect themselves from silicosis which is a respiratory ailment caused by inhalation of stone dust containing free silica. Silicosis affects breathing capacity, resistance to respiratory disease, and results in scar tissue in the lungs. Stones containing large amounts of free silica include quartz, granite, sandstone, slate, jasper, opal, amethyst, onyx, soapstone, diabase, dolomite, travertine, serpentine, marble and limestone. Stone masons, sculptors, carvers and other processors also have the obvious hazard of flying chips and thus need to to wear protective goggles when chipping or grinding.

Owners of older stone buildings should be encouraged to repair and refurbish them with recycled (salvaged) stone if there are no local sources of raw material. There is a product on the market called Rock-Face Block, which combines a sandstone fascia with a lightweight concrete block. This gives the appearance, strength and durability of a sandstone block, but for less than half the price.

(See Environ Biocomposite and Terra Firma Blocks in Non-Timber Building Materials and Builders, Earth, Mudbrick... in the Alternative Directory. See also Bush Rock, and 'Granite' above, and Tufa, below.)

STRAW

Straw for roofing has been used for millennia. Packed straw walls were common during the Tudor period in England and more recently the good folk in parts of America and Canada used straw bales to build walls when lumber was in short supply. More recently, the pressure on the world's forests and concern about greenhouse emissions has caused what was once an agricultural 'waste' to come to be regarded as a truly sustainable and energy-efficient building medium. At least one house in Sydney has been extended using pinned, cement rendered and chicken-wire reinforced straw bale construction. The cost worked out to be about half that of the nearest equivalent material (cavity brick) while having hugely superior insulation properties.

STRAWBOARD

Materials for a straw-based fibre or particle board can include , wheatstraw, oatstraw, flax, sisal, hemp, etc.

(See Biocomp in Non Timber Building Materials in the Directory. See also International Kenaf Association under Non Timber Paper.)

STRAW BALES

(See the articles in Straw Bale Building)

SYNDECRETE

In 1983, U.S. architect David Hertz developed a hand-crafted, precast, lightweight cement-based composite called Syndecrete as an alternative to nonrenewable and petroleum-based materials. Mainly specified for reception desks, table tops, basins, and planters, Syndecrete is also available in slabs or tiles for walls and floors.

It is 20 percent industrial waste like milled carpet scraps and fly ash (coal residue from electric generating plants) and 25 percent recycled aggregates (marbles, record chips, golf tees, chains, video cases, wood chips, eyeglass frames - whatever is in the client's waste stream). The remaining 55 percent is water, sand, and cement.

At its plant, the manufacturer Syndesis recycles polishing water, form-building materials, and Syndecrete dust. Since each job is custom, the company prices Syndecrete on time and materials. It usually costs the same or slightly more than granite.

TENTS, TIPIS

Perhaps best known of tent shelters is that of the nomadic, desert dwelling Bedouin peoples of Africa and Asia. The Bedouin tent* accomplishes six things at once. In the desert, temperatures often exceed 120 degrees fahrenheit - there is no shade, no air movement. The black Bedouin tent when pitched, creates a deep shade that brings one's outer body temperature down to 95 degrees. The tent has a very coarse weave, which creates a beautifully illuminated interior, having a million light fixtures. Because of the coarse weave and the black surface, the hot air inside the tent rises and is drawn through the membrane. This creates a breeze from outsidethat drops the sensible temperature further to 90 degrees. When it rains, the fibres swell up and the tent gets tight as a drum. And of course, the tent can be rolled up and transported to the next camp site.

Tipis** are the conical tents of the native American Plains Indians, consisting of animal skins stretched over timber support poles. They are easily pitched, roomy, well ventilated at all times, cool in summer, well lighted, proof against high winds and heavy downpours, and, with a fire (safely) blazing inside, provide snug warmth in the severest winter weather. Tipis are also one of the most beautiful dwelling structures ever created. Technology has improved upon the durability of the canvas, but has not been able to improve the design.

Both tipis and Bedouin tents are dwellings in which to live, not just to camp.

An Australian 'tree tent' can be made by bending the tops of a suitable cluster of small saplings toward each other until they meet. This forms the skeleton of the tent which can then be covered with a parachute or tarpaulins, etc.

* From Design, Ecology, Ethics and the Making of Things, an article published in the Spring '96 Earth Island Journal by architect William McDonough (see Books, Journals, in the Directory).

** From The Indian Tipi - its History, Construction and Use. See Books, Tipis, in the Directory.

THATCHING

Thatched roofs of locally available natural fibres have been common throughout Australia since both before and after the arrival of non-indigenous Australians. German settlers in the Barossa Valley area frequently place thatched roofs on their stone, wood or pisé dwellings.

(See Palms, Reeds and Grasses)

TREES

(See Biotecture, above).

TIN CANS

Last century, when lack of finances or materials prevented other options, many huts were built of used kerosen tins, bully beef cans, etc. Tinned Dog Hut in W.A.'s Norseman goldfields had flattened tin 'shingles' for the roof and walls of whole cans laid like bricks in clay mortar. Period photos also show people living comfortably in 100,000 litre water tanks.

TUFA

Tufa is a soft volcanic rock which hardens on contact with air. It therefore makes an ideal building material by being workable during construction, and then hard, resilient and stable once it has cured.

TURF 1

Grow your own roof! Turf or grass sod roofs were popular in Northern Europe for centuries, and are still found in Lapland. They consist of a crop of grasses and/or herbs growing in a layer of soil on top of a flattened tree bark such as birch, which is near rot-proof and watertight when placed overlapping. All of this is supported by the specially constructed roof frame. Squares of pasture soil with roots and grasses intact are placed together on the birch bark. As seasons pass, the roots intertwine between sods, thus creating a contiguous whole. Rain and other weather conditions only serve to consolidate the strength and durability of the mat.

Turf roofs are energy-efficient insulators and are self-renewing. The soil in the sod acts as a storage system for the heat produced by sunlight and plant photosynthesis during the day, while the plant fibre stabilises the mass and creates an effective thermal barrier which helps retain heat in the cold of night, and moisture during the daylight hours. Turf roofs have been tested in Germany to prove their superiority over tiles. A system of central heating has been devised to draw off excess heat from the roof and warm the interior of the house.

If accessible and sufficiently sturdy, the roof can also be part of the food source for grazing animals. A sod roofed dwelling set into the side of a hill is ideal for this.

(See also Living Structures)

TYRES

Car and truck tyres rescued from garbage landfills (!) are now being used in the U.S. to build houses. There has however been consternation at the prospect of old tyres 'out-gassing', ie giving off noxious gases after being reused or reprocessed. Material from recycled tyres has been used for retreads, acoustic materials, roofing, runways, road base, oil spill absorbers, aggregate, asphalt, speed bumps, barriers, mud flaps, doormats, car floormats, packaging, toys, watering systems, animal bedding, fences, garden borders, artificial reefs.*

Ranchers in Arizona in the U.S. are constructing erosion-control 'dams' made of old tyres, which slow rainwater runoff and act as sediment traps. (The initiative was necessitated by 300-odd years of overgrazing by cattle). The U.S. now has a scrap tyre recovery rate of 95%. Two Australian companies, Flexitec Pacific and Regupol, manufacture floor coverings and pavers, etc, from old car tyres.

(See under Builders, Car & Truck Tyres, in the Directory and The Tyre House Book, Books, Building with Tyres.)

* It has been claimed that old tyres may leach cadmium, but the Guide is unable to verify this or whether it applies only for specific brands or composites, or for older makes only. The US Environmental Protection Authority has issued a report that there is no undesirable out-gassing from tyres.

UNDERGROUND

In the 1800s, copper miners at South Australia's Burra Burra mine lived in underground houses which were set into the soft clay walls of a ravine nearby to where they worked. Their first task on arrival at Burra Creek was to dig themselves and their families a home. Each had three or four rooms with adjoing passages. Rooms were whitewashed or papered, with sleeping recesses cut into the walls. The community lived in good health in their dwellings until a series of flash floods forced them out of their 'habitable grottoes'.

VEGETABLE FIBRE

Flax, sisal, jute, ramie, indian hemp, even banana fibre - are all being used in panelling for Mercedes Benz vehicles. Many Japanese food sellers serve their meals on water-resistant 'potatotrays', ie, plates made from potato starch, which are compostable along with the food scraps. There is certainly scope for construction materials to be developed using similar techniques. Coir, from coconut fibre, and sisal, from the cactus-like agave plant are both extremely durable as floor coverings.

(See The Natural Floorcovering Centre, in Non-timber Building Materials).

VOLCANIC ROCK

(See Tufa, above)

WATER

Apart from being essential for the chemical curing of concrete and cement, water is better known for its aesthetic (and life-giving!) properties in and around the average Western dwelling. Yet its insulative abilities give it enormous potential in the design of low-energy buildings of the future.

Water-filled bottles, for example, can be built-in to make attractive, inexpensive, light-conducting walls which reduce the need for conventional materials such as bricks and render, yet can be masked to provide great insulation properties.

(See also Aquatecture, Glass and Ice and Snow, above.)

WATTLE & DAUB

(See the article Stick & Mud Building)

WHEAT STRAW

(See Wheat Straw Particle Board)

WIRE

Barbed Wire is used in conjunction with bags of sand or earth to create building units, based on ancient techniques.

Fencing wire has been used for decades to secure temporary shelters. Many bamboo houses are lashed with wire.

(See the article, Adobe & Super Block Technology)

WOODWOOL SLAB

This Guide is not aware of any woodwool slab in Australia, but it is apparently a board made of glued, compressed wood fibre ­ much like MDF. Traditional woodwool is comprised of fine wood shavings, and is used as a packing material for fragile objects, or as a filler in plaster.

Zero Point Energy

'Zero point, or space energy is the primordial energy of the universe. It offers the tantalising possibility of small, safe, cheap, clean, home-based collectors that draw on limitless free energy that surrounds the planet.' Inventor Nikola Tesla worked on harnessing this energy during the time when he introduced the idea of using alternating current to power the electricity grid ­ in place of Edison's unstable DC current.

1. RADON GAS HAZARDS

One unseen hazard with stone and other materials is that radon gas is often associated with areas which contain deposits of granite or slate. Radon is radioactive (and carcinogenic), colourless and odourless, and is a byproduct of the decay of uranium and radium. It can be found under the earth where we walk, in tar and bitumen, and in masonry building materials like brick, stone and concrete. It can also be present in groundwater.

Indoor levels of the gas are usually much more toxic than outdoor levels, so interior stone floors, etc should be assessed for this possibility and well ventilated.

Like all forms of radiation, exposure to radon gas has a cumulative effect; ie, there is no 'safe dose' or harmless level of exposure over a period of time. Documented diseases from long-term low-level exposure include leukemia, kidney cancer, melanoma and childhood cancers, birth defects and genetic mutation. Radon is said to be responsible for 20 percent of all lung cancers (the other 80 percent being tobacco-related).

To eliminate radon buildup in homes with significant levels of the gas, they should be thoroughly ventilated twice per day and/or have underfloor ventilators or gas drains installed and/or close all gaps and cavities with a (non-toxic) sealer.

The release of radon and other radioactive compounds is more prevalent where the land is subject to faulting, or where rocks such as granite occur. (Baggs, 1996)

Concrete, earth, rocks, rubble, gypsum, conventional bricks, compressed earth bricks, rammed earth walls and adobe blocks ­ these should all be checked for radon outgassing levels (there are monitoring devices available: consult your builder, architect or engineer). Pole Houses with their high ground-clearances may be the best structures to build in high radon areas. Earth-sheltered houses must have coninuous waterproof membranes in the walls and floors ­ these also provide a barrier to radon.