Straw and Earth

Anthony Spick, P. Eng. of Blackwell Bowick structural engineers of Toronto has been involved with many “natural building” projects over the past decade. They involved techniques such as straw bale walls, rammed earth bag foundations, and wood-peg joinery.

Q. WHAT KINDS OF “NATURAL BUILDING” PROJECTS HAVE YOU BEEN INVOLVED IN?

I’ve worked on six community buildings and some 40 houses. Two of the community buildings are environmental learning centres. Another was a shared food bank and thrift store in Haliburton, beside the old train station. Also I worked on a museum in Minden, and the Madoc Arts Centre.

The idea of natural building is to use local materials and materials that go through as few processes as possible. In that way we hope to reduce the amount of greenhouse gases produced in the course of creating a building and reduce any other negative effects of the building on the earth.

Most of the straw bale projects were built by hand, but I wouldn’t say that is something that has to define the building method. There are some prefabricated straw bale wall systems that are built off site and transported and craned into place. At the end of the day, I favour systems that have standardized their means and methods of construction. There are a few out there.

Q. HOW DID YOU GET INTO ALL THIS?

I started working for Blackwell Bowick right after graduation, just over eight years ago. I was always interested in work that had an environmental benefit, and one day Chris Magwood showed up with a couple of jobs looking for an engineer. Chris is a builder and one of the leaders in natural building in Canada. He had heard that as a company we are not afraid to try new things.

Currently Chris teaches the course in sustainable building and construction at Fleming College. He and the students in that program have built most of the community buildings that Blackwell Bowick has been involved in.

Q. WHAT ARE SOME OF THE TECHNOLOGIES YOU USE?

The most unusual foundations, for example, would be a rammed earth bag, which is what we used at Madoc. On the site they take something like a rice bag — white polypropylene — and fill it with earth, usually from the site. They close the end of the bag, lay it on the ground and basically ram it down with a weight. Often the weight is just a piece of concrete cast around the end of a broomstick.

On the Madoc Arts Centre another traditional technique we used was wood-peg joinery. Wood peg, or mortise and tenon, joinery was the way most timber in buildings was joined together until the early 19th century when nails started being commonly used.

A. DO YOU SEE NATURAL BUILDING AS A GROWING INDUSTRY?

Yes, I do. It’s limited to what kind of things it will be suitable for. We’re not talking about 150-metre high atriums here. I think any sustainable building needs to respond to the context in which it is built. Natural building techniques are well suited in my mind to a rural or semi-rural context.

If anyone is interested, the Natural Building Engineering Group (NBEG)( info.nbeg@gmail.com) is a peer group of Canadian engineers who help each other do this type of work.