Help with laying the two-piece hearth

[jbarlow]

Hi
I am at the stage of laying the the structural and insulating hearth layers. Can anybody clarify whether the insulating layer is built immediately after the structural layer? Or should I wait until the concrete in the structural layer has gone off?
Thanks!

[james]

You can do it either way. You can add either your vermiculite concrete layer or your solid state board insulation (FB Board, or similar) on top of wet concrete; or you can let your slab dry, and add the next layer on top of dry concrete.

Either way, you can leave the forms on the structural slab for quite a while, allowing the slab to cure.

Aren't we flexible? :-)

You can do it your way.
James

[JoeT62]

I gave it a day - enough to "set" but not to cure. But James iscoreect. It really doesn't make a difference.

Incidentally, I wanted a smaller base of insulating "vermicu-crete" than the underlying slab as I wanted to drive my enclosure studs into the "real" concrete. I was able to remove an outer strip of "vermicu-crete" quite easily with a circular saw and chisel.

Good luck!

[james]

Originally Posted by JoeT62

...I wanted a smaller base of insulating "vermicu-crete" than the underlying slab as I wanted to drive my enclosure studs into the "real" concrete. I was able to remove an outer strip of "vermicu-crete" quite easily with a circular saw and chisel.

Good luck!

That's a very good point. The insulating layer only has to be as large as the cooking floor/dome of your oven. You can either:

1. Frame in the vermiculite layer to fit under the oven;
2. Cut your FB Board to fit under your oven; or
3. Cut back your vermiculite layer after you have poured it (alla JoeT62).

This might be an area where we can update the Pompeii Oven eBook to be more clear.
James

[JoeT62]

I also used the vermicu-crete strips as insulation "filler" in the enclosure (still have the ceramic blanket and loose perlite, but maybe I needed to buy a little less perlite this way).

Of course those pieces of vermicu-crete are fun to play with. I freaked out my friend by tossing him one (they are LIGHT). Ahhhh....good times.