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Stone Dude 02-06-2013 02:29 PM

Oven cracking, need some advice
 
A little background; I work for my dad, we operate a marble and granite fabrication shop in Southern California. He has always wanted to offer brick ovens as part of our service. He has been in the tile and stone bus. for over 30 years and finally built his first oven.

I know nothing about building brick pizza ovens, so I don't have all the details, but he basically did some research for a while, got some plans together and a template to build from. He had one of our masons build the oven. It was fired up every day for about a week or so, to cure the bricks. We started using it about the second or third week. It works phenomenally, but has developed some cracks. It isn't loose or falling apart, but I want to see if we can get this figure out.

We built this as a prototype so we can get the kinks worked out. Once we build one that can be used regularly without any issues, we will tear it down and build another to test, to be sure we have it right.

anyway, I have attached a link to a photo gallery to show the issues. I figured if anyone could help, it would be you guys that deal with this stuff all the time.

If you need any more info just let me know. I appreciate any input.

Thank you.

pizza oven - Imgur

ShannonCorum 03-08-2013 05:18 AM

Re: Oven cracking, need some advice
 
Looks like you built the same oven I did. I used a form from a company online called brickwoodovens. Mine has similar cracking issues but isn't falling down, thank goodness. If you aren't against tearing it down, then that is probably the best route to go and start with insulating the floor. I don't have an endless supply of firebrick or money so I refused to tear mine down if I could avoid it. What I've done is cut out the floor inside, down to the concrete slab underneath. I am going to fill the "hole" with a 5:1:1 mix of perlite/portland cement:water. Then I will lay a new 2 1/2 firebrick floor ontop. The next big issue is the chimney. It needs to be outside the oven, not inside. I will brick up the existing chimney. Before I can build a new one out front, I will need to close up the existing doorway, down to about 9 or 10" in height and about 16" across. Then I will build a new chimney/flue out front so when I have my oven going, the smoke and soot will go up the flue and not on my front brick and in my face. Lastly, since firebrick does not provide insulation, I will add some insulation over the entire oven. This will probably be an enclosure with loose or very light perlite/portland mix. I don't want any cracking so show on the outside so I am not going to do an "igloo" like finish, I want an actual enclosure this time. Lots of work. Yes. But other than the lack of insulation under the floor and the chimney placement, my barrel vault is fine if I pick up from there. There's a site that I found a lot of really good info on. I'll send you the URL.

Tscarborough 03-08-2013 05:42 AM

Re: Oven cracking, need some advice
 
I see several issues. First the vent is not large enough.

Second it doesn't look like you used refractory cement.

Third, there is no insulation under or over the oven. Other than being a waste of wood, it also causes thermal stress in the brick as the outside will always be significantly cooler than the inner.

Fourth, you do not need that much mass, it exacerbates the third point.

Lastly, the door opening height should be constricted to 63% of the ceiling height.

stonecutter 03-08-2013 06:07 AM

Re: Oven cracking, need some advice
 
I don't even see a vent.

deejayoh 03-08-2013 09:36 AM

Re: Oven cracking, need some advice
 
I think others are being pretty gentle with the feedback. If you are really planning to make a business of this, I'd suggest sh!tcanning that prototype and starting over. That's not a "few cracks", it's teetering on collapse. The design is never going to work as well as a pompeii

Step one: download the plans for a proper dome oven from this site.

texassourdough 03-08-2013 10:18 AM

Re: Oven cracking, need some advice
 
I am with DeeJay!

That has to be one of the worst oven designs I have ever seen.

If you want to make building ovens a business, do your homework! That oven would be virtually useless as anything but a visual element - it defies about every known parameter of a good oven!

Tscarborough 03-08-2013 10:46 AM

Re: Oven cracking, need some advice
 
And sadly, there is a company already selling them online. I have helped people save themselves simply because he calls out for 2 different colored firebricks and I can tell instantly when they call what they plan on doing.

ShannonCorum 03-08-2013 11:08 AM

Re: Oven cracking, need some advice
 
Tscarborough,

Don't know if you've looked at that site lately, but he has added insulation under the floor, over the dome, and closing the opening up in his building plans now. At least it's better than it was. Too bad it's after many of us have already built our ovens and are now faced with major renovation or tear downs.

Shannon

Tscarborough 03-08-2013 11:19 AM

Re: Oven cracking, need some advice
 
Good. He needed to fix it.

brickie in oz 03-08-2013 10:07 PM

Re: Oven cracking, need some advice
 
The mortar joints are humgoius you are not building a house, for an oven less or no joints are better.


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