Ancient ingredients - new design

Construction trade sees growing use of alternative materials, strawbale and rammed earth lead the way.

Ever since genus Homo Erectus stood upright, and probably before, natural materials found in close proximity were used for shelter. From caves to yurts, tipis to log houses, Mother Nature was counted on for the supplies which mankind (and more often womankind) found new and ingenious ways to use in creating creature comforts.

Over the last few decades, home construction in North America and most of Europe has veered away from natural materials, as vinyl siding replaced more traditional wood, and asphalt shingles took the place of cedar shakes.

But in the last few years, a quiet revolution has started in the home-building industry. Brave and often visionary builders have started a return to more simple times, using such materials as straw bales and rammed earth to construct houses and utility buildings.

The process has not been without pitfalls, as "green" builders encountered resistance from local governments and building inspectors as they attempted to try something different. Alternate building materials have to be tested and proven once again to meet the needs of current building codes.

Builders using these materials have found themselves split three ways, being at the same time builders, researchers and educators.

Such is the case with Habib John Gonzalez, the acknowledged guru of the strawbale building movement in BC. Based in Nelson, Gonzalez has conducted strawbale workshops throughout BC, including sessions in Smithers, Whitehorse, the central interior and Gulf Islands. As head of Sustainable Works, Gonzalez has been involved with more than 40 strawbale building projects.

There are currently about 20 strawbale homes up to 4,000 sq. ft. built with building permits in the East and West Kootenay regions of BC. Several people in the Smithers area, Vanderhoof, and at least one in Dease Lake, have attempted strawbale construction after attending Gonzalez' workshops. Some are happy with the results and some are not, having found the process more expensive than they anticipated.

Straw has been in use as a building material virtually since the advent of agriculture. It was used to strengthen mud construction in the Middle East at the dawn of civilization. In North America, settlers used baled straw in the construction of homes, barns and schoolhouses in Nebraska more than 100 years ago.

There are two basic styles of strawbale construction: loadbearing (Nebraska style) and non-loadbearing (called infill). In either style, the thick straw walls are covered in wire mesh strung tightly, and covered in plaster, stucco or other similar materials. As with more conventional construction, proper drainage around the building and a solid foundation are critical.

"People are jumping into many new green building technologies with varying degrees of experience, and have all manner of results," said Gonzalez. "As simple as straw bale can be, it's not idiot-proof. There are international standards that have to be followed, and I will only work on permitted buildings. People should do their homework. You wouldn't try to frame a conventional house without doing some research."

Gonzalez said strawbale structures can be erected on any style of foundation providing it is properly designed and engineered, and also providing it includes a rubble trench of crushed rock or gravel under the foundation to ensure proper drainage.

Some who have attempted strawbale building in the Bulkley Valley have found it impossible to obtain bales with the proper moisture content. As part of his research, Gonzalez has developed moisture and tension

parameters for two suppliers he uses, one in the Creston Valley and another in Alberta. He says the benefits outweigh the challenges.

Among the benefits are high insulation qualities (R-43 to R-48), high sound absorption, natural and completely biodegradable material, renewable material needing only one season to grow, needs little energy to produce, diverts farm waste, and the aesthetics of a thick-walled structure with deep window sills. Compacted straw is extremely fire resistant, and also contains no nutrients to attract pests common in wood construction.

Like strawbale, rammed earth is an ancient method of building. The rammed earth method uses wooden forms that are placed and secured. Then damp earth mixed with a small amount of concrete is loaded into them and tamped to extreme compaction. When the forms are removed, the wall is complete.

Rammed earth construction received a tremendous boost in credibility when a front-page story in the Vancouver Sun Feb. 2, detailed a 6,000 sq. ft. home built of rammed earth, at a cost of $3 million, on Saltspring Island. The dwelling was built for aging rock star Randy Bachman. The Gulf Islands are a centre for alternate building materials, and Gonzalez has just completed a 3,000-sq. ft. home on Texada (at a much lower price).

While Bachman's home (palace?) featured a cast of 400 artists and tradespeople, installing curved walls and staircases colored with bands of crushed rock and shells, the Ford Escort of rammed earth construction can offer the same benefits as the Rolls Royce product.

Terra Firma Builders Ltd., which constructed Bachman's house, has modified the construction system to adapt it to any climate, including the central interior and farther north. Called the "sire wall" (stabilized, insulated rammed earth), Terra Firma's construction includes a core of foam insulation for cold climates, creating an engineered wall which surpasses code for insulation and is able to withstand major earthquakes.

"My belief is the more extreme the climate, the happier the client will be with sire walls," said Meror Krayenhoff, president of Terra Firma.

"People in (northwest BC) would be happy building with rammed earth because of the insulation factor. While the composite value of a typical stud frame house is R-17, ours is R-33. You lose half your heat through the walls, but rammed earth provides a much tighter building."

He said another advantage is the availability of material. When requested to build a home, the first thing Krayenhoff does is contact a local contractor to provide consultation on excavation and footings.

"If I was going into Smithers, the first thing I would do would be to contact a local backhoe operator. They know where the good packing soil is. It's ideal if it can be taken from the excavation for the foundation, but we want rock hard walls using 10 per cent cement. You might have to truck it five miles, but it is a common material, and not expensive. It is usually under $5,000 for the material for the house.

As with conventional construction, proper design and engineering are critical, and a rubble trench for drainage is mandatory as in strawbale construction.

"Good building design dictates every building has to have a good hat and good boots. The roof has to respond to local conditions, as does the foundation," Krayenhoff said. When it is built properly, rammed earth construction can be about 15 % more expensive than conventional wood frame. But in remote sites it can be a lot more cost competitive.

"Two weeks ago the two top bids on a house on Saturna Island were wood frame and our rammed earth. Ours came in cheaper because of the cost of getting concrete and other heavy supplies to the remote site."

Krayenhoff said proponents of rammed earth construction are looking at longevity, as well as insulation, soundproofing, good air quality, low energy and maintenance bills, and fire safety. "Wood frame houses from 25 to 40 years old are called medium," he said.

"From a European perspective, that's pathetic. We need to talk longer term and build for the longer term."

One look at the Great Wall of China gives you an idea of the durability of rammed earth.

An alternative building material primer

Recycling: Everything from old logging bridges to gymnasium floors is being recycled in home construction. Bridge beams can be re-milled, and hardwood floors and other materials from older structures removed and refitted. Reduces landfill waste.

Bamboo: A fast growing member of the grass family, bamboo can replace rebar in concrete, be used as pins in strawbale construction, and is now increasingly common in fibreboard.

Cob: Mixing local earth with sand and/or clay, along with straw or other fibrous materials, creates a stiff mud which is formed into small loaves (cobs). These cobs are then smashed together to form a monolithic wall on top of a stone or concrete foundation.

Earthen floors: A mixture of cement and earth (puddled earth) is becoming a common flooring material, and was used in Randy Bachman's rammed earth house on Saltspring Island.

Earthships: Soil-filled tires are dug into south-facing hillsides and stacked like giant bricks to form side and interior walls. Old bottles and cans are used to create a variety of detail features and fill gaps between tires. The building is framed in wood on the south side and roofed with metal to collect rainwater.

Cordwood stackwall: Most often a post-and-beam skeleton, with a combination of lime and cement between the walls as they are stacked. Can use sawdust for insulation, with five inches of cement at either end.

Hemp: Non-psychoactive hemp is being used for pressed-hemp fibreboard, with the inner pith of "hurd" used as an additive for lime-based concrete-like material.

Living roofs: Built on a sufficiently strong frame with careful waterproofing, a growing medium is placed on the roof and seeded with grass or other plants on a base of straw. Provides climatic stabilization, useful in wet, snowy climates.

(Al Price, a former Smithers resident, now lives in North Vancouver.)

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