Insulating layer

[theboss]

I’ve casted my dome, and am now about to cover with a 100mm insulating layer of the same sand2:1clay mix. I was going to include vermiculite once I’ve puddled the mix, could anyone give me a steer on quantities?
Also as the vermiculite is so light and soft is it likely to get crushed in the clay mix and then lose its insulating properties?

I’ve heard other people using sawdust, but I thought vermiculite would be better?

Cheers

[simonh]

look up vermicrete, there are a couple of options on ratios, I went with a 7:1 mix