Repairing Outdoor Pizza Oven Cracks

This is a rough guide to repairing cracks in a clay or cob oven. See details below.
When wetting the cracks it is best to use the light mist setting on a sray hose nosel. You don't want to erode the surface with the water. The idea is to get the water to penetrate the material without wearing it away.
- If your oven only has superfical plaster cracks you should be able to use the oven as soon as the cracks are dry.
- If you are repairing cracks that go all the way through the oven, realize the surface of the patch will dry first but the inner material is still wet. In this case it is better to wait the 1-2 weeks mentioned in the video.
This video ended abruptly as the repair took longer than anticipated and the wrap up and finishing of the demo got cut short. I plan to make a more comprehensive video in the future. See more details below.
MATERIALS:
Thermal Cob = 1/4 clay rich subsoil + 3/4 concrete (course) sand
Earthen Plaster = Thermal Cob + fibers
Slip = Thick clay suspension (disolved clay + water)
Thermal Cob is used in repairing cracks that go all the way through the oven. These cracks should be repaired as soon as possible. If your oven is cracking every spring this means you likely have a problem with frost heaving and you should address the cause which is likely site drainage of the foundation.
Earthen Plaster is used to repair superfical cracks in the outer plaster layer.
If you have any questions or comments please leave them in the comments. Thanks for watching.
Easy Jam by Kevin MacLeod is licensed under a Creative Commons Attribution license (creativecommon...)
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[@billyboy-59]

Thanks for taking the time to show us William.

[@tracyalcott5525]

Great Video!!! Very helpful! Going to patch my oven today! Fingers crossed it goes as well as your video!

[@tgchism]

I repaired a reoccurring expansion crack moving up for my brick arch toward the top of my dome by working a piece of stainless steel window screen into the line plaster layer. It has not returned. Also, consider rolling a coat or two of a water class solution on the inside of the oven, It strengthens the surface and keeps any fine material from falling off. I did that when my oven was new.

[@SimhaBode]

Thanks for your insights. I have wondered about adding metal mesh to the plaster cracks, but have never tried it. I imagine your level of insulation would need to be good enough that the metal doesn't heat up. If it did heat up, I would imagine this could cause even more cracking. I have never heard of water class solution. Is it a natural material, heat resistant and permiable? I have never had any issues with the interior crumbling and falling. Did you find this video through ovensdiy.com? If you are ever interested in making a post of your experience and knowledge on our new forum I would appreciate your contribution. Peace, Will

[@tgchism]

@@SimhaBode That was a type o on my part. WATER GLASS is sodium silicate. It's a sealer and or binder. I applied it on the inside if my oven when it was new as a precaution. Seems to have worked great. Yes, the mesh is above my insulation level which is 6" thick. It also is on top or a bout an inch of lime plaster. I applied a thin wet coating of new plaster and worked the mesh into that. Then built up more plaster on top of the mesh. It is really holding up well so far. I found the video just reviewing videos on cob ovens. Always like seeing what others are doing. Our oven is 7 years old. I added the brick door way after the original construction. Ive since had to replace the original keystone about the same time I worked on the crack. These ovens are very versatile and easy to work on when needed. Thanks for the invite. I will take a look at your site!

[@tgchism]

@@SimhaBode My two videos with my oven. kzbin.info/www/bejne/oHbTloWZjN6Zmrs. kzbin.info/www/bejne/hKbFg5SVeM98mbc

[@zeekoozee686]

I have the same cracks and May be worse I live in Florida Can you advice me please what the exact material and who supply them please Thank you in advance

[@cornholius]

Rad

[@doctorfloydhayworth9080]

Hey man, can I get your opinion on my cracked perlite dome? Maybe a way to send you pictures?

[@SimhaBode]

sure thing - [e-mail]

[@rthomas802]

What material is your doorway arch?

[@SimhaBode]

This arch we cast out of a DI Y refractory cement. R-Cement = 1 part Portland cement 1 part fireclay 1 part lime - Final mix - 1 part R-cement to 3 parts sand. You can see photos of the forming process on my site ovensdiy.com on the blog post - “4 Easy to make materials you need to build an outdoor pizza oven”