Newbie question about oven floor

[Giulio]

Re: Newbie question about oven floor

Will the 2" thick Alumina Silicate board be enough insulation between the firebrick and the solid base?

YES IT WILL just biult an oven with 3 in calcium siliucate board and it is as good or better tnan my first with verm concrete,
they use the boards to ins blast furnaces at 1000 c
cheers

[Tomweb]

Re: Newbie question about oven floor

Regarding heat loss from the hearth slab, one other question, from one who has yet to get his paws dirty on a WEO......but can't wait~ If we are to insulate as described, why do we not consider the uninsulated sides of the hearth slab, which represent a fairly large surface area to dissipate heat also?

[Gulf]

Re: Newbie question about oven floor

Regarding heat loss from the hearth slab, one other question, from one who has yet to get his paws dirty on a WEO......but can't wait~ If we are to insulate as described, why do we not consider the uninsulated sides of the hearth slab, which represent a fairly large surface area to dissipate heat also?

If we insulate as recommended, there will be a measurable distance of insulation between the oven and the hearth slab. If that distance is not vertical, then the insulated foot print area should be wider than the foot print of the oven.
The firebrick (floor and dome) should be totally entombed in insulation. The concrete hearth should be seperated by, depending on the type of insulation used, 2" for most commercial insulations and 4" for V/Pcrete. If the concrete hearth is seperated from the oven by these distances then there is nothing outside of the tolerances to rob the oven of heat.

[Tomweb]

Re: Newbie question about oven floor

Good visual, thanks for the clarification, Gulf.

Adequate slab insulation, extending well beyond my hearth floor, coupled with my correctly insulated dome will do the job.
Scanning the threads and reading about other builds, I can see the importance of heat retention to carry out post-pizza baking/ roasting on occasion....

[david s]

Re: Newbie question about oven floor

I recently inspected a brick oven for a home owner who inherited a home built oven on purchasing a house. The one metre internal oven had been built on a timber stand. On close inspection the timber support in the middle was badly charred. Suspecting no insulation under the floor, on lifting a floor brick (common reds had been used) there was a 1" layer of clay under which a second layer of bricks sat on a thin sheet of steel. Because the dome had been built on top of the floor, removal of both layers of floor bricks and the clay layer in between was going to be a difficult job, let alone the replacement of the supporting timber beam. I did not investigate how the dome had been insulated because I could see that becoming a second nightmare. Needless to say I declined the job of fixing it. I bet they had some fun trying to get the thing up to temperature, but they obviously did judging by the burnt support underneath.

[Neil2]

Re: Newbie question about oven floor

"extending well beyond my hearth floor,"

Well, to the limit of the dome insulation anyway. Do not "daylight" to the edge of the slab as this will create a broad entryway for moisture.