Square pizza oven

[tylerbecker]

Hello,
I would like to build my own WFO. I’m brand new to the forum and have been reading (and learning) a lot on here. I have a limited budget so I have been trying to think of a way to build an oven to suit my purposes as well as be cost-effective. It seems to me that casting my own using the homebrew mix might be the way to go. My question is: Would a rectangular 24” x 30” oven with a flat lid that sloped front front to back (18” high front wall, 12” high back wall) work? I could cast all the pieces separately and then mortar them together. Just not sure if a completely flat ceiling would work well. Thanks for any info

[UtahBeehiver]

I suggest you download the free eplans from the Forno Bravo website. The plans specifically address how heat distribution is affected by oven shape.(square/retangular vs dome) as well as other WFO construction/design processes. You can still do a dome shape cast oven. There is a well documented cast oven in the Newbie Section named Treasure Archive.

[collo]

Welcome to the forum! It’s great that you’re planning your own build on a budget.
To answer your main question directly: a completely flat, sloped ceiling is generally not recommended for a wood-fired oven, for two main reasons:

• Structural Integrity: Cast homebrew refractory mixtures have great compressive strength but very low tensile strength. A flat slab spanning 24 inches will sag, crack, and potentially collapse under thermal shock and its own weight. An arch or dome shape keeps the material under compression, making it structurally sound.
• Heat Distribution & Airflow: WFOs rely on a rolling flame that travels up the arch/dome and radiates top heat down onto the food. A flat, angled roof interrupts this convection current, creating heat traps and cold spots.

A Better Budget-Friendly Alternative:
If you want an easy build using homebrew castable, consider a barrel vault (arch) design:

1. Build a simple curved form out of insulation board or flexible hardboard.
2. Cast the arch in 3 or 4 arch sections so they are easy to lift and assemble.
3. Mortar them together over your floor.

Also, try to keep your peak interior ceiling height around 10" to 12" relative to the floor. An 18" height will trap too much heat at the top, leaving your pizza toppings undercooked while the crust burns!
Good luck with the build—casting in sections is definitely a smart, cost-effective way to go!

[david s]

The problems of uneven heating and the resulting thermal expansion particularly in brick builds can lead to stress and fractures usually created in the mortar joints. Therefore cast builds are less susceptible because there are fewer joints. At the other end of the scale, the larger the brick or cast section, the greater the chance of cracking, hence the use of loose laid floor bricks which can expand and contract individually.

While a half barrel structure may seem simpler to build than a dome, it introduces more complex issues requiring more complicated solutions.A few thousand years of millions of oven built and thousands of different design solutions experimented with have resulted in the hemisphere with its superior chamber circulation as well as its inherent stability characteristics, to be the most popular choice.

1. A half barrel oven with its internal height equal to half its width is a relatively stable structure until thermal expansion takes its toll. A 10" high ceiling would result in a 20" wide oven.

2. If the end walls are built against, rather than under the vault, the expanding vault simply pushes the end walls out.

3. If multiple sections are used in this fashion the top of each section heats and expands first, while the base remains a lot cooler, creating stress and possible fracture.

4. A larger radius vault results in far greater outward thrust at the vault's base, requiring either buttressing or bracing, as well as unworkable angles at the vault sides.

5. More vertical sides increases workability but the uneven thermal expansion remains. So brick builds in this form are far harder to construct and far less stable than cast ones.

6. Steel bracing to support structure. Buttressing is another method, but introduces far more thermal mass, requiring more fuel and longer heat up times.

7. Single piece cast dome, sometimes preferred for mobile applications.

8. Multi piece cast dome, either low ceiling or hemisphere preferred by most commercial manufacturers.