Hearth build up / strength question

[tryrook]

Ok, I'm totally a newbie on this and am learning as I go. I have built my stand (a corner model) for an angled 42" oven. I poured the concrete slab for the hearth base and then the perlite/portland cement mix to the specs outlined in the plans. The perlite mix goes right to the edges of the hearth.

My question is this: Given the structural limitations of the perlite/portland mix, what are my options for putting a finishing layer on the hearth to protect against moisture, or alternatively, can I build up walls and a roof on top of the hearth? Will the perlite/portland mix hold up with the weight?

In retrospect, I probably should have formed it off to limit the perlite to just beyond the perimeter of the dome, but it is too late for that.

Any thoughts sincerely appreciated.

[Tscarborough]

It is easy enough to remove the perlcrete from the area where your walls will be, and that is what you will need to do.

[HConrad]

Thank you for asking this question! We did the same thing, but ran short of the perlite/concrete mix.

Tscarborough, do you mean we'll need to chip off any perlite mix that does not go right under the dome? Many thanks in advance, Heather in Pittsburgh

[Neil2]

Yes. Cut back the perlite to just short of the dome. If not, and depending on your finish, this layer could be a constant source of water entry.

The way to thing of this is to draw a circle - this is the inside of the oven. Draw a circle around that - this is the brick and hearth brick, the thermal mass. Another circle around that - this is the insulation. Another circle around that- this is the support slab and finish/cladding.

[HConrad]

Just one more question. If we are going to put a layer of tile on top of the perlite level, would we still need to cut it back? Would we be better served to do so anyway?

Many thanks!

Heather