28" Oven in Seattle

[JBA]

It's been a while since I last posted on the progress of my oven build. While the oven is nearly finished and has already been used to cook pizza, I will dedicate the next few posts to documenting the build process, hoping that it might help someone in the future.

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After the hearth was poured, I drilled several holes in it and laid out ceramic tiles to elevate the 4" calcium silicate board. In hindsight, I've learned that I should have laid the ceramic tiles bottom facing up, but it should still be better than nothing.

The calsil board was cut to shape with a jigsaw and covered with aluminum foil to protect from moisture.

The firebrick was laid on a thin bed of fire clay and sand mixture. I think I was able to get the floor pretty even. Note that I placed the floor brick on their side for extra heat retention. The floor thickness is 4.5 inches.

For cutting the bricks, I used a 10" sliding composite saw from Harbor Freight that I fitted with a diamond blade. Bricks were always soaked before cutting but there was still an incredible amount of dust. A mask was a must-have.

[JBA]

Next up: Brickwork.

Building the dome tier by tier. I mixed a homebrew refractory mortar. Lots of wedges between the bricks. Flue gallery and chimney base with carefully angled cuts.

For the last tier and capstone impatience got the better of me and the fit and finish on the inside suffered a bit. Still very much functional though.

The build videos on the YouTube channel 'Artisan Made' really helped me.

[JBA]

Wide angle shot from the inside (after drying).



The top doesn't look great as mentioned in previous post.
I also didn't mortar and tuck the gaps smooth between the bricks on the inside. I don't imagine it makes much of a difference to the performance of the oven, but I'll take any advice on it into account for a future build.

[JBA]

Curing/Drying cracks after the final fire that cleared the dome:




Also note the use of an anchor plate attached with tapcon screws, sealed with high temp silicone. Double wall 3ft and 6in diameter chimney attached to anchor plate.





None of the cracks exceeded 2mm.
They occurred at the very top, around the gallery, and at the back of the dome.

[JBA]

Insulation: 3" of ceramic fiber blanket, and about 1.5" of vermicrete.





I also got a feature in the Seattle Times!

[JBA]

Oven door. Built using sheet metal and stainless steel rivets. Temporary for now until I can have someone build something nicer for me.

[MarkJerling]

Looking good. And you even got in the newspaper with it! Well done!

[david s]

Curing/Drying cracks after the final fire that cleared the dome:



None of the cracks exceeded 2mm.
They occurred at the very top, around the gallery, and at the back of the dome.

Apart from raising the temperature too fast, cracks are more likely if the drying fires are done with the the oven uninsulated. This is because there is a much greater difference between the inside and outside temperature of the bricks. This leads to uneven thermal expansion and a greater propensity for cracks to develop. If the dome is insulated the temperature is much more even. Nothing you can do now, but maybe keep this in mind for the next oven you build.

[JBA]

Since the oven was functionally finished in late July, it has been fired up about a dozen times when the weather has been dry. Apart from cooking the mandatory pizzas, I've also tried my hand at pita bread, ratatouille, fish, roasting various vegetables and chicken, and even things like lentil soup using retained heat. Speaking of retained heat... the generous insulation and extra floor thickness really holds in the heat for a long period of time!

It's been exciting to cook various foods in the oven and understanding the dynamics of it. Hopefully the oven does well sitting under a tarp through the wet season in Seattle. Next spring I plan on adding the remaining cosmetic touches such as pouring a concrete countertop around the oven, rendering the dome and stand, and adding a few coats of paint.

Here's a few pictures of foods cooked in the oven: