question about hearth slab framing

[cook4fun]

Re: question about hearth slab framing

Greetings fellow FB fans...a question: I'm having the concrete block for my oven done by a builder, I have provided him all the specs, dimension (WxL) as well as height...I want a 4 inch layer of perlite / portland on the top (ration of 6:1), so here's the Q...should I have him do the entire "top" (measuring 6 x 6) with this mixture, or should I sketch out the dimensions (shape) of my oven, and have him make a frame with that shape, and only fill that in with the mixture, then fill the remainder with "just" Portland (asked another way, if the mixture is all on the top, will there be any wicking of heat / moisture to be concerned about ?

Thanks to all that can provide thoughts or guidance.

PS: I currently live in Germany, and will return home in June, so that's why we have a builder doing this work.

[johnnybrewmeister]

Re: question about hearth slab framing

Why not use 2x6 boards like I did? It worked great. I had my wife help me hold the boards up. I had them about an inch or so below the "slab" that I was laying. This way I was able to suck it tight to my concrete block to hold it into place. I put 2 screws in each end to hold the boards. I just worked my way around. Put one board up, measured 3.5", made sure it was level as I screwed in my next board. The last joint was a little tough because I had to make sure it was very tight, but I really liked how it turned out. I dont even know if I 'needed' the support boards, but put them there just in case.

I poured my slab just a couple weeks ago. Make sure you have enough concrete, I didn't. Hope it helps.

Nice framing idea...this would have worked for me I think...anyway, I'm enjoying your build thread, learning lots along the way. Thanks for sharing.

[DavidApp]

Re: question about hearth slab framing

Hello Cook4fun

I would have him make a form and pour the insulating layer in the shape of the oven making sure it is big enough for the dome bricks to sit on the insulating layer. The perlite / Portland mixture is a little fragile so a concrete band around it helps to protect the edge.
My 2 cents worth.

David

[Greenman]

Re: question about hearth slab framing

Hello Cook4fun

I would have him make a form and pour the insulating layer in the shape of the oven making sure it is big enough for the dome bricks to sit on the insulating layer. The perlite / Portland mixture is a little fragile so a concrete band around it helps to protect the edge.
My 2 cents worth.

David

Something like this. It also pays to have a hole in the middle of the 'keyhole' so any water that finds its way under the hearth can drain away. This worked for me and is easy enough to do.

[almondsurf]

Re: question about hearth slab framing

Nice framing idea...this would have worked for me I think...anyway, I'm enjoying your build thread, learning lots along the way. Thanks for sharing.

My pleasure! Feel free to follow my thread... I'm sure to make lots of mistakes that you may learn NOT to do. Building the oven is fun... Right now I have to be patient as it's drying out, but it's fun.

[Les]

Re: question about hearth slab framing

Thanks for all the tips!

Stonecutter, the "legs" are already shimmed to level things out and stabilize, but still it is quite wobbly.

SableSprings/Mike, I've already learned from your past experience, because I was gonna screw some braces to the top to see if that would help - now I won't try this.
I like your idea of the wire...might give that a shot.

NCMan, are you saying you just screwed some of your "legs" to the block stand? I could probably get some tapcon screws (if they aren't too pricey).

Les, I can't honestly picture what you're describing. Got any pics? I know I've been thru your build thread, maybe it is time for a re-visit.

Thanks,
John.

John, I know this is a little late - just saw your request. This is the best I can find. The wood you see is supported from the bottom ( inside the storage area) and is basically floating inside the block. http://www.fornobravo.com/forum/f8/s...arth-1850.html