I just took out the supporting forms underneath the slab a few days ago, and I just noticed three separate cracks in the earth slab. In addition to 2x4 wood framing underneath, I had square blocks stacked underneath the center of the slab which i had intended on leaving in there. The blocks seemed loose and weren't supporting much weight at all so I decided to take them out to make more room for wood storage. I did have to use a hammer to knock out the wooden supports... maybe I was ignorant in thinking that a few thousand pounds over my head would never move? I used a mix of 3/8" and 1/2" rebar every 6-8" when I poured the hearth 3 months ago, and I completed my dome 6 weeks ago.
I have read all of the different posts about cracked hearth, but my situation seems to be unique in that the cracks formed right after I removed the supports while at the same time I'm almost done curing my oven and it's the first time the hearth has potentially experienced heat with cool evenings right at freezing temp. I have not been able to find any cracks in the foundation slab, and cannot see if the cracks underneath hearth because cement board is covering it.
3 cracks:
-Front center that continues into the quickwall layer underneath the archway firebrick
-Back center that continues both 3" into the dome and 3" into cement block below
-Right center (not pictured) same as back center
-Left side center crack
Should I put a support back in the center under the slab?? Maybe a basement jack post? Huge thanks for any advice!
I have read all of the different posts about cracked hearth, but my situation seems to be unique in that the cracks formed right after I removed the supports while at the same time I'm almost done curing my oven and it's the first time the hearth has potentially experienced heat with cool evenings right at freezing temp. I have not been able to find any cracks in the foundation slab, and cannot see if the cracks underneath hearth because cement board is covering it.
3 cracks:
-Front center that continues into the quickwall layer underneath the archway firebrick
-Back center that continues both 3" into the dome and 3" into cement block below
-Right center (not pictured) same as back center
-Left side center crack
Should I put a support back in the center under the slab?? Maybe a basement jack post? Huge thanks for any advice!
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