I'm considering a project that would include adding a solar space to an exterior south wall of an existing house and replacing what's on and between the 2x4 studs of the back wall ( about 10 foot length of it)with cob.
Then on the inside of this wall have a rocket mass heater for heating the small home.
Will it work to infill with cob this way? Would the cob be too thin to stand up?
Has anyone done cob infill to act as thermal mass?
It would be plastered post infill both interiorly and exteriorly.There would be a door( with glass panel) to the solar space from the house as well as adequate venting in the solar walls and house wall.
All thoughts/input on this idea greatly appreciated.
I wouldn't do it.. Cob really should be built separate from wood members, they tend to reject each other if inter-penetrated.. I'd use light straw or something similar with the frame and put the thermal mass inside somehow.
I had initially considered clay slip and straw but figured it didn't hold enough thermal energy compared to cob. I recognize that 4 or 5 inches of whatever I use isn't much but it is better than nothing. I think?
Clay slip and straw is still a possibility with earthen plasters on both sides.
Would adding medium size rocks throughout the clay straw mix add more thermal mass?
All input appreciated.
An ancient technique for fixing cob into a wood frame is called wattle and daub. You groove or drill the frame, set thin poles usually vertically in the middle of the wall thickness, weave flexible laths or branches into those like a loose basket, and apply cob on each side. The wooden parts secure the cob to the frame all around. This is often relatively thin, but could be made as thick as desired.
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