Wrong dimensions - Help!!

[peterthewolf]

Re: Wrong dimensions - Help!!

So far it has been suggested that we use penetrating sealer, and also this option of the bituthane type. Sealer may not last over time; certainly the bituthane would in normal conditions. But what about when the oven burns hot? We realize because of the brick floor layer over it and an airspace (not to mention the metal plate beneath brick) that heat coming down won't be at it's extreme, but certainly there is going to be heat. We already know this because the floor rapidly and continuously drained heat out of the oven. That means that some significant heat will hit the bituthane below across the airspace. Any chance we'd end up with a slight signature pizza flavor from vapors?

Pros and cons: That was con. Here's pro. Since we are demo-ing all the way down, the metal floor support is solid, not in pieces. So the only place for vapors to go is sideways, into the walls. Heat does push out, but gasses expand to fill the size of their container which means if there are any vapors from this material, I want to be totally sure our food doesn't taste like someone is tarring the roof next door. This kind of puts me back to favoring a penetrating sealer that is dry cured once it is dry. Last question on this: Metal fabricator said as long as we are using the firebrick (of course, that's the floor) over his metal, 3/8 inch is plenty without worry of warping it. Steel is a hell of a vapor barrier, except for condensation from cold wet underneath. Ah, did I just reinforce the need for sealing that slab... Or does it really matter what happens below the steel as long as there *is* an air space beneath it, wet, dry, whatever?

[Laurentius]

Re: Wrong dimensions - Help!!

What type of insulation is under your fire brick to prevent your heat drain?

[peterthewolf]

Re: Wrong dimensions - Help!!

Laurentius-
Uh, none but an air space so far. Ok, now I get it. I was taking this literally, and of course, will be following fornobravo plans, as has also just been suggested again to read fine detail of plans for sure (thanks UK). I don't know why I didn't see this before but I thought I was being advised to leave an air space. Now it is coming to me that yes I should, however, I should then *fill* that air space with insulating material - not just a chamber of open air.

Ok then. For this reason of adding insulation - it is the bituthane layer that will serve to keep water from coming up into the insulation - and the insulation will keep heat from damaging or out-gassing the bituthane. Since the slab is 2 inches above weepy ground (directly on it), and will then be covered with the bituthane moisture barrier, the new insulation will stay dry. Right?

Now. That leaves one more thing. Once we are finished blasting, we'll be finding out whether the dome walls and the insulation inside them were sitting *outside* and *below* that slab directly on weepy ground. In that case, we will need to build slab upward from the ground in a large donut around the existing slab to elevate above weepy ground. Then we can do the same bituthane application on it before rebuilding the dome.

Right??

As for insulation, we already know about vermiculite. But do you folks want to make a better suggestion? Can I stuff fiberglass blanket into that space before putting the metal floor down? And finally, I had 4 inches of space to excavate old wet vermiculite and replace. Minus 3/8 inch steel under floor support to bring brick floor back to where it was. So almost 4 inches of space to re-insulate. What's better than vermiculite?

[peterthewolf]

Re: Wrong dimensions - Help!!

Laurentius-
Uh, none but an air space so far. Ok, now I get it. I was taking this literally, and of course, will be following fornobravo plans (except that this is not an "elevated tabletop level" oven) as has also just been suggested again to read fine detail of plans for sure (thanks UK). I don't know why I didn't see this before but I thought I was being advised to leave an air space. Now it is coming to me that yes I should, however, I should then *fill* that air space with insulating material - not just a chamber of open air.

Ok then. For this reason of adding insulation - it is the bituthane layer that will serve to keep water from coming up into the insulation - and the insulation will keep heat from damaging or out-gassing the bituthane. Since the slab is 2 inches above weepy ground (directly on it), and will then be covered with the bituthane moisture barrier, the new insulation will stay dry. Right?

Now. That leaves one more thing. Once we are finished blasting, we'll be finding out whether the dome walls and the insulation inside them were sitting *outside* and *below* that slab directly on weepy ground. In that case, we will need to build slab upward from the ground in a large donut around the existing slab to elevate above weepy ground. Then we can do the same bituthane application on it before rebuilding the dome.

Right??

As for insulation, we already know about vermiculite. But do you folks want to make a better suggestion? Can I stuff fiberglass blanket into that space before putting the metal floor down? And finally, I had 4 inches of space to excavate old wet vermiculite and replace. Minus 3/8 inch steel under floor support to bring brick floor back to where it was. So almost 4 inches of space to re-insulate. What's better (and equal/easier) than vermiculite?

[Laurentius]

Re: Wrong dimensions - Help!!

I for one prefer Ceramic Fiber board for my floor and Ceramic fiber Blanket for my dome, and if you enclose your dome add the vermiculite mixture.
As I write we are have another earthquake after shock.

[dmun]

Re: Wrong dimensions - Help!!

Can I stuff fiberglass blanket into that space before putting the metal floor down?

Domestic fiberglass has organic binders that burn and stink with much more than attic heat. I'd go with refractory board or vermiculite concrete.