Stacked brick oven on steroids

[seannieboy71]

Like many others, I got the itch to build a pizza oven after seeing a YouTube video of a perlcrete exercise ball pizza oven build. But after doing some research it became apparent that it wasn’t a good approach and I decided against it. During those searches I ran across other videos of people making stacked brick ovens and my mind fixated on that concept. I hadn’t found this forum at that point.

I was attracted by how quickly the oven could be used after being built. And so I used suggested dimensions from a couple of forums (pinkbird.org and traditionaloven.com) to come up with a design. I ended up with a pretty big oven.

I was able to start the fire in the oven for the first pizza cooking session while I was finishing the chimney. The picture is what it looked like when first used.

[seannieboy71]

I ended up changing the chimney and adding a file pipe. I also coated the outside of the bricks with Quikrete Quikwall surface bonding cement to stabilize the structure and stop the leaks between the blocks.

After a few more pizza nights with friends and family, I insulated the oven with 3.5 inches of mineral wool insulation. I was planning to use ceramic fiber blanket but after doing the comparisons and calculations, the mineral wool is a better insulation and significantly less expensive. It also worked for my oven since all of the surfaces are flat.

The insulation seems to work well. The inside upper wall temp was 900F and the temp on the outside at the same
position was 90F with an ambient temperature of 85F.

The oven does have quite a bit of thermal mass and it takes about two hours to get up to pizza temps, 900F + for the ceiling and 700F+ for the hearth. But I have enough residual heat to bake cookies (350F) 40+ hours later.

In addition to pizza I have cooked roasts, dessert pizzas, Biga wheat bread (Forno bravo recipe), artisan bread, cookies, German pancakes, and steaks. The steaks turned out amazing. And the s’mores pizza I read about on this form is delicious!

I worry about the longevity of the oven due to the use of regular clay bricks and the method of construction. But I find great satisfaction in cooking for friends and the enjoyment from watching the fire. I would do it differently if I were to do it again. But I don’t regret that I have been able to use the oven throughout most of the construction effort.

[seannieboy71]

The finished oven. The only remaining work is to embellish with decorations.

[Mongo]

Fascinating. Well done!
Did you use a steel plate for the ceiling of the cooking chamber? Thickness?
What about the steel used in your flue gallery?
I see what looks like 9 inch square tiles on the floor of your flue gallery. What are those? Do they extend into the oven?
What's the material directly under your oven floor bricks?

[seannieboy71]

I have 4 inches of 5:1 perlcrete under the oven. I wish I had done 6 inches. The tiles are 6x6 in sealed red clay quarry tiles. They extend through the entire oven. I thought they would be a better cooking surface than the bare bricks. I need to replace a few hat have cracked. They cost 5I cents each and I bought extras. We'll see how long I continue to use them.

The roof is supported by T cross section iron bar. The T is inverted and I ground the ends of the bricks so that the bar didn’t add to the height or length of the oven. The stresses on the steel are low, even with two layers of brick for the roof. My concerns with the steel are corrosion over time due to the steam created from burning wood and also creep due to the prolonged exposure to elevated temperature with constant stress. Time will tell how well it will hold up. The attached picture shows the roof from the inside of the oven before the first firing.

I used angle iron to support the bricks that span the opening of the flue gallery and the oven door.

the oven cooking surface is 30 x 34 and the flue gallery is 19 wide by 15.5 deep. The door is 15 x 10.5 and the roof is 18 high.

thanks for taking the interest to respond.

[seannieboy71]

The tiles are unsealed, not in sealed. Autocorrect got me again.

[seannieboy71]

Lesson learned. All of the tiles inside the oven on the hearth ended up cracking. Although the nice smooth surface was nice to cook on, I ended up removing them all and will cook directly on the bricks. Thankfully I did not mortar them in place.

I also started embellishing the oven. Since I live in southern Arizona, I want it to have that style.

[gigelus2k20]

Phenomenal results for such a simple design!

it's interesting that the hearth reached only 750F while the ceiling got to 900F, is this an issue of the bottom insulation?

How is the burn behavior in such a boxy design? Is the flue efficient at removing all the smoke?

The red bricks will crack in time, they are more brittle than firebricks, but it's a very simple and inexpensive design, so fixing it won't be an issue. What size T-bar have you used? I couldn't find any T-bar in my area (except humongous structural-sized stock) and I ended up using angle bar with pieces of cut angle bar welded to it to create a home-made T-bar

[seannieboy71]

interesting points. I hope the red clay bricks don’t crack too soon. I found the T-bar at Industrial Metal Supply. It was expensive. Looking back, I would just use two pieces of angle iron instead on the T-bar. Would have cost 1/4 of the T-bar.

I lose a lot of heat through the base. 4” inches of perlcrete is not enough.

I get smoke out the front of the gallery during startup even with a preheated flue. I stop most of it by using a piece of cement board to close off the upper two thirds of the gallery opening. I rest the bottom edge of the cement board on two cut pieces of brick to allow air in for the fire. Once the fire is burning well, I remove the cement board.

About thirty minutes before cooking pizza, I spread the fire around All the sides of the oven and add wood on all the sides. This heats the oven up evenly. Then I move the fire to one side for cooking pizza.

Heat retention is okay. The oven is at 250F 48 hours after cooking pizza. The outside temperature probably helped with that. The high today at my house was 105F.

[Jubilado]

I am curious that you used the terracotta tile on your hearth and the cracking you experienced. I am in late design phase of my oven and considering adding clay tile on top of the oven floor.

I live in Mexico, so saltillo tiles are not hard to get. I need to query about quality, as there are many manufacturers, from cottage sellers to mass produced. I see some tiles are sintered at 1000C, others don't say what temperature. I doubt that all of them are processed at 1000C. You might ask your tile supplier about this.

I see that one can purchase rather expensive terracotta tiles just for this purpose from Italy. From what I read I think a material with lower thermal conductivity is desirable on the hearth to allow the bottom of the pizza to cook slower to equal heating of the top of the pie. The slower take-up of heat would eliminate or lessen a need for 'doming.'

I've looked for other materials. Stone conducts heat about as well as dense fire brick, in general. There is volcanic rock slabs available here, which are porous basalt. Even with the porosity, the thermal conductivity is high.

I plan to postpone the purchase of tiles. I think that they can be added later. I think that the right quality floor tiles could be laid over a thin layer of sand or clay mortar? to compensate for the formed cleats or pattern on the bottom of the tile.

Perhaps others have experience with a clay tile cooking surface.

[MarkJerling]

Like many others, I got the itch to build a pizza oven after seeing a YouTube video of a perlcrete exercise ball pizza oven build. But after doing some research it became apparent that it wasn’t a good approach and I decided against it. During those searches I ran across other videos of people making stacked brick ovens and my mind fixated on that concept. I hadn’t found this forum at that point.

I was attracted by how quickly the oven could be used after being built. And so I used suggested dimensions from a couple of forums (pinkbird.org and traditionaloven.com) to come up with a design. I ended up with a pretty big oven.

I was able to start the fire in the oven for the first pizza cooking session while I was finishing the chimney. The picture is what it looked like when first used.

Cool! I have seen a few youtube videos about stacked brick ovens. It's like Lego on steroids! LOL
I trust you have no earthquakes? Here by us, in New Zealand, that would turn into a pile of bricks very quickly, unfortunately.

[david s]

It's not really the temperature the tiles are fired to that determines their resistance to thermal shock, it's the clay composition (high in alumina. low in fluxes) In fact lower fired clay has better thermal shock characteristics as evidenced by the low fired Sth American and African wares that can be placed on a stove.

Regarding the T section steel to support the roof, an alternative is to drill holes through the bricks and thread them on to a threaded rod with washers and nuts on either end. The brick sections can be tied together with the rods also penetrating some angle iron at the ends. I built a top loading jewellery kiln using this method years ago, it worked like a charm.

I reckon you will find your oven performance improves, re the floor insulation, the more you use it. It takes many firings to dry the floor insulation if you used a vermicrete brew. Try drilling a few holes up from the bottom, through the supporting slab to allow moisture too vent.