I dropped by to visit my friends Nathan and Maggie (and Laurelynn) on Sunday and found their yard bustling with activity. They were hosting a work party to help build a workshop behind their house. Nathan is a passionate woodworker and tinkerer and wanted plenty of space for his hobbies (although I think he also wanted an excuse to build a building using cool natural building techniques).
The foundation, framing, and metal roof had all been installed previously and this work party was focused on filling in the walls. Slipstraw is pretty straightforward. Once the frame of the building is up, you come through and screw a piece of plywood about 2 feet tall to the inside and the outside. This makes a little box and the empty space is where you want the wall. The wall itself will be made of slipstraw and the plywood will eventually be removed. (In this main picture of the building, all you see are the finished slipstraw walls where the plywood has been removed.)
To make slipstraw, mix clay and straw until it is a slimy, sticky, mess and then shove it in between the pieces of plywood. The goal is to basically make bricks in place so the next step is to pound it as hard as possible and keep adding more slipstraw. Eventually it will be packed so tightly that you can remove the plywood and the slipstraw will harden into place. Oh, and you can also put in windows as you go, slipstrawing around them. They used some awesome retro-looking glass blocks.
Nathan said (if I remember correctly) that the seeds in the straw will sprout shortly after you’ve pounded your walls into place, while the clay is still wet. However, as the slipstraw dries out, the sprouts will die. So you wait until your walls turn green and then die and turn brown again and then you know it’s dry. Then you come through with a protective coating of earthen plaster on each side. They are planning to stick with a basic mud-color brown for the outside but use a bit of whitewash on the inside to give it more of a finished look and lighten up the interior. Their chicken coop has a protective coating of earthen plaster that has stayed rock hard in the four years since they built it so they’re feeling very confident that the building will hold up well.
So why the fuss about natural building? Part of it is a desire to minimize use of nonrenewable resources and potentially toxic substances. Part is the joy of creating a building using materials you gathered yourself. (In this case, the clay came from the pond they are digging in the backyard and the straw was purchased from a farmer outside of town.) And part of it is certainly aesthetics; it’s much more original than vinyl siding, at least in this neck of the woods. There’s also an element of adventure and a degree of flexibility in most natural building styles. I don’t have the physical strength to lug bricks around but I can build a house one armful of muddy straw at a time without taxing myself. The slipstraw part also doesn’t take much skill, although it does take a lot of labor and it definitely helps to have someone in charge who can make sure that the slipstraw is not too wet, not too dry, and pounded just hard enough. For now, I’m content to be the grunt labor for an hour or two and then stand back and admire the building coming together.