Barrel Vault Design

[okn]

I’m considering a few different options in designing my oven. Attached is a sketch of one of the basic ideas. Please note that the foundation is notional and I will be using the basic FB base design with angle iron etc., but plan on only having the hearth slab rest on 4” of the 8” wide CMU. Will this provide enough support? Another question is can I stack the 4”wide CMU on top of the 8”wide CMU and reinforce it with rebar all the way up? That gap between the outer oven wall and the CMU will be filled with perlcrete. Will that provide enough buttressing support to counteract the outward force of the arch? Any help would be appreciated, as I have never laid a block in my life (which may be painfully obvious from the design).

[brickie in oz]

Originally Posted by okn

That gap between the outer oven wall and the CMU will be filled with perlcrete. Will that provide enough buttressing support to counteract the outward force of the arch?

The perlcrete should stop it from moving, you should also consider ceramic blanket over the oven before the perlcrete as it will hold more heat in the oven, it will also allow for some expansion movement.

[david s]

With all that perlcrete as insulation you will be adding LOTS of water (about 1/3 of the volume of perlcrete) so you will take a long time to remove it. Try leaving the roof off your enclosure until you"ve expelled all the water.
If you use blanket on the sides of the oven you will lose the butressing effect as it can compress. Suggest you use blanket over the arch and end walls, but not the side walls.

[okn]

I appreciate th replies, and will definitely head the advise about using a thermal blanket on the top. Are there any other issues I may run into that you can see? Will the slab foundation be OK just resting on half on the 8" wide CMU?

[david s]

Are there any other issues I may run into that you can see? Will the slab foundation be OK just resting on half on the 8" wide CMU?[/QUOTE]

Yes should be ok especially if you've tied it in with rebar as per drawing.
If doing a barrel vault you should have the end walls inside the the arch rather than outside.

[brickie in oz]

100mm bearing for a slab is plenty.