Hebel base

[surfingyogini]

Hi everyone, I’ve been lurking and learning for a while now as hubby and I do a slow build (sitting around a year) on our pizza oven here in SEQ but find myself needing help. We’re almost up to the dome!

I wasn’t sure where to post this so am sticking it here… for those that have used hebel as insulation on the base (under the firebrick cooking surface), how have you placed them on the suspended slab? I’m thinking of leaving them loose and just in brickies sand?

This is the current state of affairs:

[UtahBeehiver]

You can look at Oasiscdm thread, he used hebel in his build. It is an okay floor insulator not the best, not the worst. So it depends on how you are going to use the oven. A 25 to 50 mm layer of CaSi would vastly improve the floor insulation characteristics.

[fox]

You base looks quite low?

[surfingyogini]

UtahBeehiver Thanks. I looked at that but he used a whole sheet. We have a suspended slab (@fox it’s sitting around 120cms off the ground and I’m only 150cms so it can’t go much higher!) and then 75mm hebel bricks with 25mm fire bricks on top of those. I’ve read that most people just use brickies sand for their fire bricks but I wondered if I could do the same for the hebel blocks?

[UtahBeehiver]

You should still consider CaSi on top of the hebel blocks, even 25mm would improve the floor insulation alot.

[MarkJerling]

I used 75mm (3 inches) of Hebel panel over my slab. It has worked well. Over the top of that I have sand and then my oven floor. There is virtually no heat transfer to the supporting slab under.

[UtahBeehiver]

FYI, here are the published K values (thermal conductivity - lower is better) of Hebel is 0.11 and CaSi is 0.05. CaSi has better thermal properties by a factor of 2 but it is also more expensive and very water absorbent. I suspect AAC has much higher compressive strength and less water absorbency to there are trade offs.