Question about wrapping timber frames in light straw clay

I am working on a building for a job in the countryside in china. In part of the building the client wants the timber frames inside the light straw clay walls. The walls are 30cm thick and the timber frame (square) posts are 20X20cm, so that would leave 5cm if light straw clay on both sides of the timber frames to tamp in the LSC. Is it possible to imbed that into the light straw clay wall, or is that too thin of for the wall to hold. I'm concerned that it might fall off the wall in the thin areas where the LSC covers the posts. They also are in areas around corners where the posts have to embedded (leaving 5 cm of space to tamp into). I could make the walls 35 cm... but it really feels like a thick wall at that point

Much thanks in advance.

Hello Michael,  Welcome to Permies....  I don't have any specific experience with your question but in 'the books' it is often recommended to key in joints using nails or wood slats to help bond the two surfaces together and keep it from cracking. Anything really that will add a definite texture to the the wooden beam that the straw clay can bind better to.
I know for cob walls, totally embedding a beam in the cob is not recommended but rather to have surfaces of the beam left exposed. Perhaps its to allow for the expansion/contraction of the beam.
With LSC this might not be an issue with all the tensile strength from the straw unless the logs are still green and could trap that moisture in there causing mold.

Perhaps someone with more experience in this area will chime in to help. Good luck!

thanks for your response Gerry. I was wondering then, if i am tamping the light straw clay then it seems that having nails in place would get in the way of tamping (with all the nails in there). is it that you put in the nails after the tamping? with cob its easy but with the small space between the form and the LSC with a bunch of nails in there, i don't think that's possible. Any thoughts on that. Thanks

michael pope wrote:thanks for your response Gerry. I was wondering then, if i am tamping the light straw clay then it seems that having nails in place would get in the way of tamping (with all the nails in there). is it that you put in the nails after the tamping? with cob its easy but with the small space between the form and the LSC with a bunch of nails in there, i don't think that's possible. Any thoughts on that. Thanks

I think the issue might be, the timber frame beams will shrink once they are dried out. At 1 inch per year to dry, an 8 inch timber frame beam would take 8 years to be fully dry, so it is impossible to dry them out before building with them, hence they move.

But one idea I can think of...maybe...is to secure chicken wire or hardware cloth to the beams. That way when you put on your straw clay mixture, it will grab onto that hardware cloth grid, and help hold it in place. You could tamp all you liked then and it would just adhere more to the wire.

thanks travis. the wood is old recycled from torn down houses, so there's no issues with any shrinkage. i think the idea about the chicken wire will probably work well. maybe jest leave small spacers between the wood and the chicken wire the LSC can get into that space...

michael pope wrote:thanks travis. the wood is old recycled from torn down houses, so there's no issues with any shrinkage. i think the idea about the chicken wire will probably work well. maybe jest leave small spacers between the wood and the chicken wire the LSC can get into that space...

You could stand off the chicken wire a bit with screws driven into the beams, and then tie with wire or zip ties.

Hi Travis. i am considering to move the wall so that there is 10cm of LSC covering the post on the outside and and on the post is flush with the wall on the inside.  then i just have to cover the post (20cm wide) with something (mesh or otherwise to plaster over it) so its sort of a leaves me to work it out during plastering... but at least the wall will be stable along the posts. if anyone has any other suggestions or thoughts, i always welcome them.... but time is sort of limited, this is china and they literally work around the clock on these large construction jobs in the countryside.