Forum / Dome wall thickness


The thicker the walls of a wood fired pizza oven the greater the thermal mass the oven will have. The thermal mass of a traditional oven in conjunction with the effectiveness of the insulation determines how long the oven takes to heat up, the amount of thermal energy that can be stored, and the duration that will take the oven to cool down. A long cool down duration will allow for the cooking of different food items sequentially after the fire has expired. For example an oven brought to temperature for cooking pizza may then be used for roasting, and baking of bread, and then finally drying of fruits such as tomatoes at the later stages. Generally it is recommended that that for a personal home use oven the dome have a thickness of 4 inches (10 cm or 1 fire brick) and the insulation also be 4 inches (10cm) thick.

The material used for the walls and for the insulation additionally affects the oven effectiveness along with the thickness. A medium such as fire brick which has a very high bulk density and heat conductive properties requires less thickness than a less effective medium such as cob. Similarly with the insulation, fire blanket is generally more effective than insulating fire brick or vermiculite cement, and thus the thickness chosen will depend on the material chosen. When choosing the wall and insulation material the efficiency of the material, the initial costs and ongoing operation costs, and the types of food to be cooked should all be considered. The below table gives example thicknesses, heat up and cool down times for an oven constructed out of fire brick and vermiculite cement as insulation.

Internal Dome ThicknessInsulation ThicknessHeat Up DurationCool Down Duration
4" (10cm)4" (10cm)1 hour12 hours
4" (10cm)2" (5cm)2 hour6 hours
2" (5cm)4" (10cm)30 minutes4 hours
6" (15cm)6" (15cm)2 hour24 hours
· 5 months ago

I believe the measurement in cm's on third line has to bel 5 cm dome, 10 cm insulation. Am i wright?

Adam · 5 months ago

That's right. The conversions were incorrect. These are just estimates however generally the outcome is that oven wall thickness will slow heat up duration and increase the time it takes for the oven to cool down due to thermal mass. Insulation will multiply this effect.

· 5 months ago

newbie question; can the dome be made with the full length of the brick with the small end facing inside the dome, and can the large spacing of brick on the outside of the dome be filled with fire brick cut into wedges with a thin layer of mortar or is this unnecessary overkill.

Adam · 5 months ago

Yeah that's the normal approach. You should have the length of the brick towards the inside and outside of the dome so that the small surface area of the brick is visible internally. If you're concerned about the long bricks being difficult to stack you can use a mallet to break the brick in half and use half bricks to create the dome. Display the clean ends of the broken bricks internally for a nice wall. The cut ends of the brick will be covered by the insulation. 

· 4 months ago

  • Brandt Seegmiller

    This is Brandt,

    I understand that  the main difference between a brick oven, and a refractory oven, is the heat up times, and the cool down times.  I am designing a barrel shaped oven for backyard use. I am wanting a quicker heat up time, and I do not need 72 hours of heat to bake bread. 

    If I set the dome Fire bricks on the flat, instead of on edge, (a 2.5 inch thick dome vs 4.25 inches) will I get a heat up time closer to refractory construction? Refractory is denser so it can be thinner,  Will 2.5 inches of brick be enough to reach and hold pizza temps?


    · 4 months ago

    I did the math for any of you out there that might want to build an oven of different dimentions. 
    with 99% certenty the cool down duration can be calculated as =(1,06667*insulation thickness)+(1,46667*inner dom wall thickness)

    with 66% certanyty the heatup duration can be calculated as = ((0,26*inner dom wall thickness)-(0,13*insulation thickness))*60 

    i multiply by 60 to get it in minutes. These numbers should be good enough to get you going 

    · 4 months ago

    my calculations are in cm btw

    · 3 months ago

    Hi so I've got insulation which is 25mm thick fire bricks at 115mm thick halves. If I'm reading it correctly the insulation should be 100mm thick, so does that mean I need to have a 75mm render over the top? Cheers dan

    · 2 months ago

    No, 25 + 115 - 100 = 42

    Render should be 42mm