I’m collecting materials to build a small Timberframe art studio. I want to use clay straw fill for walls/ insulation. I have less than 5% clay in my soil (jar test) and I can’t seem to find clay to buy. Any ideas?
Does pond clay work?
Hi Johan. Welcome!
You know, I've always known the jar test to be just an approximation of what a soil is like and not an absolute. You may find that the amount of clay in your soil is enough for your needs.
Go ahead and make a small test wall with it and see how well it holds together. Light straw clay is not really meant to be that strong anyway so it may be just fine.
Also it is good to consider what you will be covering the interior and exterior walls with. If your on-site material contains a low amount of clay as it is you might have difficulty in creating an earthen plaster which is an ideal application to straw-clay walls mainly for managing moisture. Gerry is right in that very little clay is needed in getting straw clay (slipstraw) to hold its form but it sounds like you might run into more trouble coming up with enough clay for your plasters and finish work. Still it is possible to have functional plasters with lower clay content than desirable but in that case it is more important that they remain dry as they are not as durable.
Hi Johan. I've made decent straw slip walls with the subsoil on the property, which is mostly silt and about 10% clay. They hold together and are strong as long as they are tamped into the forms really well. When it comes time to plaster you have a couple of options. One would be to use lime plaster, and the other would be to use the low clay earth mix and finish it with wheat paste to keep it from dusting. Friends of ours with similar silty soil did the latter and it worked beautifully.
posted 1 year ago
Thank you! I’m glad I reached out to Permies. I appreciate you sharing your ideas. Both you and Gerry have helped me feel like my goal wasn’t a lost cause.
posted 1 year ago
And to Aaron as well! Thank you!
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