Block Wall - Hearth Form Question

[charger10s]

I am building my oven in the corner of my yard, in the corner of two block walls (see pic). I am going to lay concrete board and build the form on the non-wall sides as it it normally done.

I'm wondering about the wall sides; I want the hearth to go all the way to the wall, with no gaps for water to run down under the stand. I was thinking I could simply pour using the wall as the form and be done with it. Does anybody anticpate any problems with the hearth being in direct contact with the block wall? Should I put in something to act as an expansion joint between the wall and the hearth? Any thoughts?

Thanks!

[dmun]

Re: Block Wall - Hearth Form Question

I think the worst problem you could have is that there would be a crack develop at that point, which would be pretty much the same as if you did some kind of slip plane there. How are you going to finish the oven? Will there be a roof, or an exposed dome? If a dome, have you thought about rainwater drainage from behind it? The oven floor should be flat, but i think you would need some sort of drainage slope, lest water gather and soak into your oven enclosure.

[charger10s]

Re: Block Wall - Hearth Form Question

I think the worst problem you could have is that there would be a .......... .lest water gather and soak into your oven enclosure.

I am going to finish with an igloo enclosure. I was thinking about the drainage issue as well the other day. Should I try and slope the hearth away from the dome into some channel along the wall? Would that be terribly hard to do?

Another idea I had was to put some holes along the wall connected to some PVC pipes that could channel the water down and out from under the stand.

Luckily, it doesn't rain much here in Arizona, but when it does, it's usually alot!

[RES10CUE]

Re: Block Wall - Hearth Form Question

You could place an expansion joint type material against the wall. But prior to placing your concrete slice the material 3/4" down from the top and tape the back side or wall side. After the concrete is dry pick out the 3/4" peice and the tape. Then pick up a "self leveling sealant" they are kept in the concrete isle at HD. It should be a "Silka" brand. This will seal the space and allow for expansion. This stuff flows like crazy make sure you tape off everything well. I hope this helps.

[charger10s]

Re: Block Wall - Hearth Form Question

You could place an expansion joint type material against the wall. But prior to placing your concrete slice the material 3/4" down from the top and tape the back side or wall side. After the concrete is dry pick out the 3/4" peice and the tape. Then pick up a "self leveling sealant" they are kept in the concrete isle at HD. It should be a "Silka" brand. This will seal the space and allow for expansion. This stuff flows like crazy make sure you tape off everything well. I hope this helps.

Thanks, that's exactly what I am doing. I cut 4" strips of plywood to use against the block wall, and I cut the top 3/4" per your suggestion. I used a simple caulk to stick the wood to the wall, and I will pick it out after the concrete sets.