Greetings from Minnesota Introductions Discuss Greetings from Minnesota in the Good Background Information forums; Hello, my name is Eric, and I am about half-way into the construction of an indoor 36" Pompeii. What an ...

[Eric Pfeifer]

Hello, my name is Eric, and I am about half-way into the construction of an indoor 36" Pompeii. What an ordeal in Minnesota! The outside foundation next to my home's kitchen had to be dug 48" down, and then we poured a 12-foot tall reinforced concrete box to get the hearth platform to the right level in the kitchen. The one night I made the leap and took a sledge hammer and busted the kitchen wall out. Last week I poured the structural part of the hearth and now it's time to set in the insulating hearth. I bought four 2" ceramic insulating boards and plan to set these in a bed of perlite-portland. In three or four days when the stuff cures, I get to do the fun I have been waiting for--laying the brick. As this labor of love progresses, I have now one question which I think will require the experience of the group, and it centers around the insulating boards:

The FB insulating boards I received seem to have good compressive strengh, more than enough I think to support the firebrick oven floor. I am worried about the walls of the dome, which will transfer close to 1000 pounds, if not more to the boards beneath them. From the perspective of an amateur engineer, this weight will be distributed over appx. 100 square inches, and again I think there is no need to worry about the compressive strength of the FB boards. But what about after a heat? The ceramic material is expected to shrink, and has anyone noticed deformation of the dome relative to the floor after a few firings? Probably not. But I'd thought I'd ask before setting in this relatively expensive part of the build.

Many thanks!
Eric

[dbhansen]

Welcome Eric! Wish I could've installed my oven indoors -- walking through the snow to load it up is not my idea of fun. I didn't use FB board, but I'm certain there is nothing to be concerned about in terms of its strength, unless your dome will be supporting part of your house.

[mfiore]

Welcome, Eric. I, too, would love an indoor oven! I agree with Daren (as always). You should be fine.

[Les]

Eric,

In my thread "les' build", page 12, link 138 - you can see where I drove my truck onto the board. It did compress the leading edge (to be expected) where the tire rolled onto it. After that, it went nowhere. I also left some out in the snow and rain all winter with weight on it - again, no probs. The stuff appears to be fairly bullet proof.

Les...

[james]

One of the characteristics of FB Board (and ceramic fiber insulation in general) is very little expansion and contraction during heat up and cool down.
James

[mfiore]

Originally Posted by Les

The stuff appears to be fairly bullet proof.

Les...

C'mon, Les. You need to test this out next!

[Les]

Originally Posted by mfiore

C'mon, Les. You need to test this out next!

Damn - I threw all the scrap away when cleaning out the shop. I just bought a sweet little Kel-Tec 380 - It would have been fun to post a pic of that. Its the smallest 380 on the planet.

Les...

[jmhepworth]

The FB Board will be fine. Enjoy the journey.

Joe

[Eric Pfeifer]

Thanks, folks! I jumped in, and tonight a friend and installed the FB boards on a layer of pearlcrete. The boards were fairly easy to level, and had only minor variations in thickness. By the Germans these boards are not made, but they seem like they will work super well. I took an oxy-acetylene torch and fired a piece of scrap, and the center glowed like one of those space shuttle tiles you see on TV; I could immediately handle the piece by the edges--super stuff!

Thanks again!
Eric