Clean building practices are the line of defense against the thoughtless, ubiquitous use of toxic building materials. The Slow Space Movement advocates for buildings that are good, clean and fair. This is Part 2 of a two-part series on toxic building materials and sustainable building solutions.
Many toxic materials lurk in our homes and buildings, and they are a danger to our health and the planet. So what is the solution? We think it is going back to basics, slowing down the techno frenzy and learning from techniques that have been tried and tested for thousands of years. I am not going to give up my iPhone, but I want to stop jumping on the bandwagon of every new material technology.
The perfect wall: Mud hut with framing, a bark weather barrier, dirt insulation and grass rainscreen.
This past summer, my husband and partner in (solving the building industry’s toxic materials) crime, Andrew, and I took the kids to Norway, where we always like to visit the Norwegian Museum of Cultural History because they have assembled buildings there from all over the country, extending back a thousand years. For instance, there is a recreation of one of the oldest native structures that offers us a great lesson in building science for cold climates.
This mud hut has framing, a bark weather barrier, dirt insulation and grass rainscreen. In fact, this wall assembly meets the definition of a “perfect wall” as defined by Joe Lstibureck and the Building Science Corporation.
From this example we can start to build a list of clean, healthy building materials. Chemical-free, non-toxic, natural materials: wood, bark, dirt and grass. We could also add stone, straw, clay, cork, wool, sand, leather, hemp, brick, bamboo. Any others?
Speaking of wool, I am reminded again of Joe Lstibureck and his sweater analogy.
A true Joe Lstibureck-ism: To stay warm, it is much more efficient to wear your sweater, rather than eating it.
Joe is a funny guy. In a building science seminar Andrew and I took with him, he was describing some fundamentals of insulation. He explained that in Canada, where he and all great building scientists are from, they have learned that to stay warm, it is much more efficient to wear your sweater, rather than eating it. Huh? What he meant was, put your insulation outboard of the framing, not between the studs.
It is much more efficient to wear your sweater, rather than eating it.
Wool Insulation: Buildings have sweaters.
But instead of expanded polystyrene (yuck!), why don’t we actually use wool? It is renewable, non-toxic and no animals need be hurt in the process. We have been shearing sheep for thousands of years.
Wool Batts. Image by Havelock Wool.
Builder Magazine recently featured a wool batt insulation product by Havelock Wool. Wool, the article says, is naturally mold resistant, flame resistant and the amino acids in it naturally bond with and trap harmful chemicals improving indoor air quality. I know this is still an example of eating the sweater, but at least the sweater is non-toxic.
The warming hut by Aamodt/Plumb on the frozen Red River in Winnipeg uses wool felt for insulation.
Warming hut by Aamodt/Plumb on the frozen Red River in Winnipeg. Photo by Dan Harper.
We have worked with wool felt a bit, and it is a wonderful product. We used it here to line the interior of the Warming Hut we did on the frozen Red River in Winnipeg. The felt acted as a warm blanket, keeping out wind and cold and reminded us of carpets or pelts that line indigenous tents and huts.
Hemp is an example of a material you really should eat as it is loaded with healthy essential fatty acids.
Clean materials you can eat. Images by Hemp for Victory.
Hemp can also be used for clothing, building materials and fuel for your car. The only thing you can’t do with it is get high. That is hemp’s naughty cousin, marijuana. On this website “The History of Hemp,” it explains that hemp was a staple crop for thousands of years, and still is in many developing countries, because it is so useful and easy to grow just about anywhere. But around 1900, big companies like Dupont were threatened by the cheap sustainable material and had it outlawed.
But it’s coming back, and we can help. Hemp literally has thousands of uses. A quote from a hemp website gives us an idea:
“I wake up in bed in the morning on my hemp sheets, on my hemp mattress, on my hemp bed frame, and I put my hemp slippers on, and I walk across my hemp carpet. I drink my hemp smoothie, brush my teeth with hemp toothpaste, slip on my hemp clothes and drive my hemp car, which burns hemp fuel.”
I have never used hempcrete, but a little research uncovers that this non-structural hemp and lime material comes as cast-in-place or block form. It is an excellent insulation and air barrier that is vapor permeable, and it is pest, rot and fire resistant. I think it would work really well as a rigid insulation outboard of the framing with a rainscreen or stucco over it.
Hemp walls by Steffen Welsch Architects. Photos by Steffen Welsch Architects.
Steffen Welsch Architects in Australia uses exposed hemp walls. And there are many other examples of low-tech building techniques that use inherently clean materials and many architects like Mass Design Group, Shigeru Ban and Studio Mumbai, are using them in very modern ways. Rammed earth, tadelakt, and charred wood are ancient building techniques that are finding new favor because of their inherent beauty and connection to the earth as well as our own humanity.
Building practices have evolved slowly over time. Photo by Studio Mumbai.
Building practices evolve slowly over time to meet our needs, and through trial and error, cultures have learned what works and what doesn’t. But the the pace of innovation is so fast now that the feedback loop doesn’t reach us until thousands of buildings are built and hundreds of thousands of people are affected. What will our future selves say about the materials we are using today?
Building practices evolve slowly over time to meet our needs, and through trial and error, cultures have learned what works and what doesn’t. But the the pace of innovation is so fast now that the feedback loop doesn’t reach us until thousands of buildings are built and hundreds of thousands of people are affected.
