Planning my 32" cast oven

[AndreasP]

Made a bit more progress last weekend. I was able to attach the cast entrance
I tied it off with the wires I had cast into it and filled the gap with 10:1 Vcrete.
Unfortunately it is not bonding well with the cured concrete (kind of expected)

I am planning on redoing it as follows:

• stuff gap approx. 1/2" - 3/4" with fiber blanket
• cover fiber blanket and gap with Rutland Fireplace mortar, works up to 2000F, plenty for the entrance dome.

I am wondering, will the above approach work?
Will the mortar bond to the cured concrete surfaces (both the gallery and cast entrance)?
Instead of buying the Fireplace mortar, should I just mix up a bit more Homebrew and use that?

Any suggestions?

[david s]

My design also employs the same design feature. It allows the inner parts of the oven to expand and contract freely inside the cooler outer shell and decorative arch. I have tried a number of solutions and like you l fill the gap with blanket and seal it off at the top with some vermicrete around 6 mm thick. I make it a bit richer (5:1) and run a pointing tool over it to compress it into the space. Obviously there are some bonding issues and the gap will fill with ash anyhow. You don’t want it to be too strong because you are asking it to act as an expansion joint, so it can’t be too strong. I’ve tried high temp silicon, but it’s not durable enough in that position. Other refractory caulks also failed which just go hard but not flexible. A floatingstainless cover over the gap is another solution that I’ve not pursued. I don’t bother filling the gap on the sides or at the top but just rely on the air gap which prevents conduction heat travel.
Let us know what you’ve come up with.

[AndreasP]

Thinking of changing my approach to the final render. Instead of finishing it with stucco I am thinking of tiling the dome in the hopes of getting a more waterproof finish.

I have looked around on the boards here and am wondering:

1. It seems that most people add a scratch and brown coat of stucco, then tile on top of that with an acrylic adhesive
   • How thick would you make these layers. I don't have a lot of space around the back of the dome and the thinner the better
   • I would plan to use a tile adhesive used for shower tiles
2. Any suggestions for the grout? Again, I would use what is used for showers
3. I am thinking of using a waterproof paintable membrane below the tiles. I know the challenge of keeping water in, but I have a vent hole at the top and around the chimney pipe
   • Where would this membrane go? I am thinking that on top of the brown coat (right below the tiles) seems to make the most sense, any suggestions?

Any feedback would be appreciated.

[AndreasP]

My design also employs the same design feature. It allows the inner parts of the oven to expand and contract freely inside the cooler outer shell and decorative arch. I have tried a number of solutions and like you l fill the gap with blanket and seal it off at the top with some vermicrete around 6 mm thick. I make it a bit richer (5:1) and run a pointing tool over it to compress it into the space. Obviously there are some bonding issues and the gap will fill with ash anyhow. You don’t want it to be too strong because you are asking it to act as an expansion joint, so it can’t be too strong. I’ve tried high temp silicon, but it’s not durable enough in that position. Other refractory caulks also failed which just go hard but not flexible. A floatingstainless cover over the gap is another solution that I’ve not pursued. I don’t bother filling the gap on the sides or at the top but just rely on the air gap which prevents conduction heat travel.
Let us know what you’ve come up with.

David, for now I decided to leave it as is. Last time I made pizza I had no issue with V-crete falling onto the pizza. I was worried about that form my attempt to fill the top and side gaps.

[AndreasP]

Made some progress last weekend.
Covered the oven with the scratch and brown coat.
Covered the whole thing with plastic to let it cure slowly.

I will wait for a week before painting it with RedGuard. Once that is dry I will add the tiles.

Hopefully the breather hole at the top and the V-crete being uncovered around the chimney with flashing on top will be enough to keep the tiles / stucco / oven from cracking should any water get into it.

[AndreasP]

Finally, the pizza oven is done. Thanks a lot to everybody who helped me realize this oven! It's been a fun journey.

To finish the oven I

• Painted the stucco with Red Guard to add a waterproofing membrane to the oven.
• Tiled with penny round tiles

The tiling was a lot of effort. Had to cut the sheets in strips one tile wide so that I could try and follow the round dome shape.

I may still paint the chimney black, but that won't take long.

Another pizza party tomorrow.

[MarkJerling]

That looks really nice. I keep thinking I'd like to mosaic mine.

[AndreasP]

Thanks, if I did it again I would pay even more attention to the surface of the dome and make sure it's really smooth without any ridges or dips. It'll make tiling a bit easier.

Also, cutting the sheets into strips really helped.

Initially I tried using a while sheet for the bottom, then strips if three tiles wide, but i had to take them off again to go single tile strip. It's just too easy to see the seams.

[Kvanbael]

That is a beautiful penny tile finish! Wow! That must have been very unforegiving for irregularities. Curious to see how it aligns towards the back.

[AndreasP]

Thanks, yes, it took a lot of time and effort.
Luckily the back is against the wall, so you basically can't see it unless you climb up onto the counter and lean over.

The biggest challenge was that three was only about an inch between the oven and the back wall.

I just took a sheet, slid it down and tried to push it against the oven with a stick.
Same for the grout. Tried to squeeze it in with my hand, then a stick and scrape most of it off.

Here is a photo from as far from the back as you can see it.

[MarkJerling]

Andreas, that looks so nice. Time for me to start shopping for mosaics! LOL

[gnwjr]

Very good looking pizza oven, my congratulations on the completion.

I’m getting close to completing the dome on mine, another 5-6 rows, then the curing fires. I’ll do those before 3 inches of ceramic insulation followed by a rendering stucco scratch coat and a brown coat. All that to ask about what results you’ve seen regarding the RedGuard? I’ve been thinking the same thing, but there seems to be a lack of information.

Take care and again thanks,
Glen

[UtahBeehiver]

IMHO, I would not cure until you have the insulation on the dome but before you stucco. Insulating the dome reduces the temperature differential between the inside and outside of the dome during the cure thus reducing the potential of thermal shock cracking.

[AndreasP]

Glen,
Not sure how to judge the effectiveness of the Red Guard.
It went on really easy and seems to be quite durable. A nice thick rubbery layer. I used 2 coats.

From the way it looked after I had applied it I think it will do the job of keeping water out very well.
I hope that the Red Guard together with the flashing I placed and sealed around the bottom as well as the tiles below the insulation will keep the oven from getting wet.

It doesn't rain much where I am, so it will probably not be until next fall that I find out if it is really waterproof.

[gnwjr]

Ok, thanks. If you come across anything, please let me know.