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ArkansasOven 12-19-2010 12:06 PM

cracks and settling
I am trying to decide wether or not to tear down my oven and start from scratch. I did the barrel vault design. There are cracks thru the heatstop mortar that seperate it from the brick, and its bad in some places. There are places where u can see how the brick shifted and settled after firing.
Is this common? I dont know if I need to cover the cracks with mortar and finish the build or ???

Any and all help/suggestions would be appreciated. I am getting very discouraged with what I have now and not sure what direction to take.

Thank you.

Neil2 12-19-2010 12:13 PM

Re: cracks and settling
Any pictures ?

ArkansasOven 12-19-2010 12:26 PM

Re: cracks and settling

I dont have pics and taking them now would be a bit misleading. After reading some posts a few weeks back on how to handle crack repair I ground out the mortar in preperation for laying a new bed of mortar into the cracks.

I have been on hold with this since it has gotten colder, work and a small vacation.

Tscarborough 12-19-2010 12:30 PM

Re: cracks and settling
There should be zero amount of settlement. Settlement will appear as displaced brick, i.e. not cracking, per se, but bricks that move in or out for lack of a better descriptor.

If the settlement is in the entry arch it is probably due to lack of buttressing, but really, without pictures it is futile to guess.

ArkansasOven 12-19-2010 12:40 PM

Re: cracks and settling
The first picture shows where the bricks that support the outer wall are beginning to move/shift away from the rest of the floor.

The second is a crack in the dome that developed with the cold weather. I havent fired the oven in over a month.



ArkansasOven 12-19-2010 12:47 PM

Re: cracks and settling
There were also 5 bricks that seperated cleanly from the mortar in the back of the oven that I have removed in anticipation of either putting them back in with hopes they stay put or as a beginning of the demolition and starting over.

Tscarborough 12-19-2010 12:51 PM

Re: cracks and settling
Can't tell anything from the first, the second is shrinkage cracking.

If there is settlement, the dimensions of the arch will change.

dmun 12-19-2010 12:52 PM

Re: cracks and settling
Ovens crack. It's mostly because they are constantly in motion, expanding with every heating cycle, and shrinking when they cool. Depending on which plan you used, there is a lot of thermal mass around the brick shell, mostly a LOT of concrete. They're built like bomb shelters. Neither of the cracks you've shown seem to be structural to me.

I'd say, if the cracks bother you, grind them out and repoint them. You shouldn't do this until your oven is thoroughly cured. Many people, myself included, have been running ovens with cracks for years, without damage to the food or the oven.

ArkansasOven 12-19-2010 01:02 PM

Re: cracks and settling
It seems that what I am feeling is fear that something will go wrong once I get the entry done and the oven covered. So far it really is just a brick cave. Nothing covering it, no entry...
From what I am gathering from further reading and the kind posts here, is to finish the oven and enjoy it.
Is there a recommendation on how to cover the brick? Vermicrete? Ceramic blanket? I plan to build a house around it to conceal the messy brickwork, but if there is a preferred way to cover this beast to help insulate and hold it together that is what I want to do before building the house.

dmun 12-19-2010 03:44 PM

Re: cracks and settling
Your question about insulation sort of implies that it's the first you've thought about the issue. My apologies in advance if this isn't the case.

Your oven should of course be covered by a minimum of two inches of refractory blanket insulation, or four inches of vermiculite concrete. If you're building an enclosure you can fill it with loose vermiculite, but the same four inches of coverage applies.

The thing is, you need a similar amount of insulation under your oven (two inches board, or four inches vermicrete) This would be the only situation under which you should consider a re-do. Nothing reduces oven efficiency, usability, and practicality like not having proper insulation.

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