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RCANCILLA 04-26-2009 04:38 AM

Curing - Testing Without Insulation
Hi, I'm still fairly new at this, but I thought I'd pass this little experience along in hopes of helping someone else avoid a cracked mortar misadventure.

I went through the curing process without insulation on my Premio so that I could observe dome looking for cracks, etc. Meanwhile I had already constructed 4" concrete block for the enclosure.

Near the end of the curing process when temps got pretty high, I noticed some nasty cracks along mortar joints and in a couple of instances actually cracked block. At first, I thought it was due to shoddy construction of the walls.

Eventually I realized that the cracks appeared in the two areas closest to the dome - the sides. Even though I have about 6" clearance It wasn't enough. I guess insulation doesn’t do much good if you don't use it.

Oh Well. Live and learn.

mfiore 04-26-2009 04:56 AM

Re: Curing - Testing Without Insulation
Which block are you referring to. Cracks on the dome/arch are common. If your cracks are not part of the dome, are they of the supporting structure? I'm a little more concerned about that. Photos?

RCANCILLA 04-26-2009 05:22 AM

Re: Curing - Testing Without Insulation
The cracks are in the wall surrounding the dome. When I got to the curing stage 800+ degrees.The heat radiated to 4" block wall clossest to the dome. I shouln't have built the walls until I cured the oven and insulated it.

The dome is fine. We've been using it every night for about a week. Everyone absolutely loves the pizza and steaks and pork chops and on and on!

mfiore 04-26-2009 06:56 AM

Re: Curing - Testing Without Insulation
Gotcha. I was worried you meant the supporting stand.

texassourdough 04-26-2009 09:27 AM

Re: Curing - Testing Without Insulation
I think everyone gets some surprises when they build an oven. In my case it is the fact that my chimney should be a bit taller, that the angle iron expands a lot more than I thought it would (and "works" my chimney a bit), and that designing to keep rain out of the guts of the oven is pretty critical. That said, none of it is a big problem, just as your wall block cracks are not likely to be.

Hang in there and enjoy the pizzas!

RCANCILLA 04-26-2009 10:05 AM

Re: Curing - Testing Without Insulation
Now that you mention chimney, dmun suggested that I distribute most if not all of the weight of the chase bricks to the pad. Is that what you attempted with the angle iron?

I am attempting to do that by using a 4" I-beam behind the vent supported on both sides by columns of block. I think the beam was a bit of overkill, but I had it available to me for free. This is the best I could come up with.

I'm not an engineer, but I recon that the vent will be supporting less that 1/2 of the weight. I will build up to the level of the bricks in front and then bridge from front to back with 2.5" cut concrete peices and then build with brick from there.

I am attempting to attach pictures. I would appreciate any comments or suggestions.

christo 04-26-2009 10:11 AM

Re: Curing - Testing Without Insulation
Wow! Actually cracked the block outside the oven. I understand no inslutaion yet - but you likely had a 4 to 6 inch air gap between the oven dome and your block to allow for insulation. How much air space between the dome and the block that cracked?

I suppose too, if the motar were fresh between the blocks it could have dried vs. cured....

As far as the I-beam - I'm pretty certain it will carry most any load related to support a stand alone oven chimney. Pictures or sketches of what you intend to do will surely help.

Btw - If you want tall chimney Dmun's build has lots of great info - DMuns chimney went clear up the side of his house, so he likely has one of the tallest chimneys on this list.

Good luck,


RCANCILLA 04-26-2009 11:44 AM

Re: Curing - Testing Without Insulation
Right, the mnortar did not have enough time to cure. And to make matters worse, there was mortar debree making contact with the dome and block.

I tried to attach pictures, but it didn't work for some reason. I'll try again.

Thanks for the suggestion.

texassourdough 04-27-2009 12:36 PM

Re: Curing - Testing Without Insulation
QUOTE: dmun suggested that I distribute most if not all of the weight of the chase bricks to the pad. Is that what you attempted with the angle iron?

I have an FB oven that includes a door so we built a square opening in front of the oven and used angle iron across the opening (like a square fireplace) to support the front of the chimney. I had the help of a longtime retired mason who had built a few real fireplaces but never a WFO. The expansion of the angle iron is "interesting" but causes no problems - the cracks on the chimney simply open and close. My chimney and base are covered with sandstone and (because of its porous structure) it is probably not the best choice (but it does look good with my property...)

larrya1049 04-27-2009 01:55 PM

Re: Curing - Testing Without Insulation
Yikes! that was path I was going to head down. It seemed like it would be easier to pack the insulation between the double brick walls after drying out the dome. Thanks for the heads up. I'll be sure that insulation is between the inner and outer brick walls and not expose the outer bricks to such a high heat. Thanks

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