Natural Building with Slipstraw

Slipstraw WorkshopI 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.)
Mixing slipstraw

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.

Pounding slipstraw into place

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.

Window in slipstraw wallSo 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.

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6 Responses so far »

  1. 1

    Andy said,

    June 30, 2008 @ 11:02 pm

    Awesome! That is a different technique than I have seen before. I lived right next to a cob house the past year, which is the same materials except you throw the chunks of cob onto the wall and then poke it with a stick to weave together the straw pieces instead of pounding them. On the other side was a strawbale house which is made with a regular timber frame and then full bales of straw 18 inches thick are stacked around the frame, ground down to be a little more flat, and then plastered over. Both very neat techniques that can be made with all local materials.

    I spent a few days this past week helping someone make a cob bench on the side of the street by their friend’s house. It’s really fun to get your hands and feet dirty in the process and really get into it!

    And here’s a really neat one: http://abg.smugmug.com/gallery/2343207_ba8FL/1/122659491_3GyQq/Medium
    It’s a cobbed wall with glass bottles throughout it. I saw this on a permaculture farm in New Zealand, and it’s actually a composting toilet outhouse.

    Just for some clarification, straw doesn’t have seeds by definition. It is hay which has seeds. From your pictures it looks like the method they used was halfway between strawbaling and cob that I have seen. Was this in Ohio?

  2. 2

    Maggie said,

    July 1, 2008 @ 9:11 am

    This project is in Bloomington, Indiana. There are also some cob and straw bale houses in the area and I have played with both techniques, as well as another that used slipstraw but wove it around upright sticks to make a thinner wall without the 2×4 frame.

    This stuff is a lot lighter than cob (no sand, much less clay) but it’s a pretty similar concept. I have seen some beautiful cob structures, especially from folks who use glass bottles. There was a fair amount of cob at Lost Valley, in Oregon, where I studied permaculture. However, cob seems to hold up better in drier climates; it can develop cracks if it gets wet and dries again. I think slipstraw might do better but I’m not sure.

    You’re right about straw and hay although I have never seen straw that was completely seed-free. That comment was something I overheard as I was walking by so he could have been talking about sliphay or whatnot. I’ll double check on that.

  3. 3

    Jessica said,

    July 1, 2008 @ 6:49 pm

    The real question is, where do you get friends who would want to come help with a project like that? I’m quite certain that if I attempted it, I’d be on my own. To many of my friends are opposed to manual labor and/or getting dirty.
    Sigh.

  4. 4

    Andy said,

    July 1, 2008 @ 10:06 pm

    Jessica, people actually pay money to help out on cob/strawbale projects often. It’s funny, I have helped out on many that are just looking for help, but there are some which say they are a workshop and charge $150 for a day, but are nothing more than the “come-help-me-because-i-cant-do-this-all-myself!” ones.

  5. 5

    Maggie said,

    July 3, 2008 @ 10:20 pm

    Yeah, it takes a lot of labor to do natural building but Andy is right that there are lots of people who will pay for the learning experience, if you’re in the right place. Plus, with work parties, people can come and work for just a half hour or they can stay for the entire day if they’re into it. (I’m more of the half-hour worker myself.)

    Many forms of natural building will let you work slowly in little bits so if you want to do a little yourself one day and then have a big work crew one weekend and then let it sit for a couple of weeks, that can be an option. But labor is definitely something to think about when you plan any building project.

  6. 6

    slip straw construction | mayaland said,

    December 14, 2012 @ 11:45 am

    [...] are some other folks doing slip-straw construction and blogging about it, here, here, here, and here.  Here is an interesting thread on the permies (as in permiculture, I think) [...]

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