Round shape

[brickie in oz]

Replace it.
Put a plaque or something over it..

Do you think the brick got that hot that it cracked?

Edit:-
Have you got a roof over it yet?

[Gulf]

Originally Posted by Mike D

I am less worried about the fire brick part of the crack (it is so small). The crack in the red brick Just looks bad and it makes a way for water to get in when it rains.

-Any ideas how to fix it?

Mike

I have never tried this on an oven or fire place:
I had a few cracks above a couple of windows and one real good one on a knee wall on my front porch. For the mortor joints I used a tube of exterior latex mortor patch (HD or Lowes) I can't remember which. This stuff was mortor gray and had sand already mixed in. (In you case I would just use the plane gray exterior latex with no sand mixed in. It will be easier to squeeze into the crack) For the brick I got the closest colored exterior latex that I could find. Try rubbing a little brick dust over the face of the brick while the patch is still wet then wipe off all of the excess. The mortor joints may require a slightly damp rag to remove the excess. I would do the mortor joints first and wait till they are completely dry then move on to the face brick. I believe that the latex will have enough flex to make the crack at least only obvious to you.

I am new to WFO's but as for as water proofing goes, I also believe in a permanent roof over the oven.

[Mike D]

-Alright I am back at it after a long long time off. I am ready to finish this oven. Sorry guys for the wait.

- I have the copper sleeve and top chimney cap (copper) that will go around the flue pipe wrapped in fire blanket. I was planning on filling the empty space with loose dry vermiculite up to a level height (but not all the way up to the brim).

-Then I was thinking of putting a mesh screen on top of the dry vermiculite, to keep it in place, then putting a layer of Vermicucrete (with some reinforcement) as a cap. This cap would go around the copper sleeve, to somewhat hold it in place. To keep the water from getting in from the sleeve, I was going to use a High temp silicone.
-I was thinking of putting a small intentional gap in between the sleeve and the vermicucrete to fill it with the silicone. Does that make sense?

-What ratio mix of Vermicucrete should I use for this cap?

-On top of the Vermicucrete I was going to use a SBC or a stucco with some type of acrylic additive, to keep the water out. But that will happen later after the vermicucrete drys out.

-Mike

[david s]

This is my solution. The two terra cotta caps allow moisture from the insulating layer to pass between them and out to the atmosphere. If you make too rich a vermicrete mixture at the top then you trap the moisture in.

[Mike D]

What do you mean too rich of a vermiculite mix, too much vermiculite or too much portland cement? I was thinking it could be lighter (less cement) than the insulating layer under the oven because it didn't need the strength. I forget what the normal bottom insulation mix ratio is (10 to 1 ?).
-Mike

[david s]

Too rich = too much Portland cement. The recommended under floor insulation ratio is 5:1. The dome insulation is better at 10:1. This layer is not under compression and only has to support itself to stand up by itself and be firm enough to render over it so a minimal amount of cement is better.

[Mike D]

Thanks David-

-I looked back in my old threads and saw that I used a 6 to 1 mix under the oven with 2" ceramic board on top. I will use a 10 to 1 mix on the top.
-I was going to put wire bars/masonary ladder (that people use to connect brick/block together) with a wire mesh to reinforce the vermicucret cap.
-what do you guys think about the sbc or stucco on top?
-Mike

[david s]

"-what do you guys think about the sbc or stucco on top?"

It's your choice, the outer shell is only to keep the thing weatherproof. but make sure you eliminate the water from the oven and the vermicrete layer before you do your stucco, otherwise the steam will probably crack the outer shell, regardless of how much reo you put in it. Remember one litre of water = 1000 litres of steam.

[Mike D]

Will do on the curing David, thanks for the help.

Mike

[Mike D]

Can you put normal stucco on top of SBC? I have some left over SBC and was thinking of putting a layer on top of the vermicucrete cap to give it a structural bond, and then finish with a normal stucco for aesthetics. I don't think the SBC looks that nice (you see the little fiberglass pieces).

Mike