Question about Insulation and the Placement of the Oven

I plan to construct my oven from 3x6x9" fire brick on top of a 4" concrete slab. The bottom of the oven floor will be 2" high density ceramic fiber board with 1.5" fire brick on top of it. I also plan to have 2 layers of 2" thick 6# blanket over the top and sides of oven.

My question is, should the side walls of the oven be on top of the 2" ceramic board or would it be okay to have the side walls directly on the concrete and the ceramic board in between the walls and back, basically the fire brick would be a perimeter around the ceramic board?

I’m wondering if it would be better to have a 4 inch thick ceramic fiber floor between the concrete slab and fire brick cooking surface leaving the fire brick walls (underside of the walls) to be in direct contact with the concrete slab but butt up against the ceramic fiber board versus a 2" layer of fiber board that is under the floor AND the walls? I’m probably over thinking this but I’d rather be safe than sorry.

Thanks in advance!

4" of ceramic board is quite a bit. Like Hostess Cupcake bakery type thickness…

The average Weekend Warrior would only need about 2" of insulation board. Maybe 3"…

But 4"? Unless you have the word Bakery or Pizzeria next to your home address, you probably don’t need it.

As for butting the walls of the oven up to the insulation - vs. having the oven walls on TOP of the insulation - I think your thought process is correct. Put the oven walls up to the edge of the Insulation Board corners - not overlapping.

That much weight - could possibly crush the board. Not likely… but could.

It could never, ever, ever crush concrete.

Thx -

Hey Kevin,

I appreciate the response. I know I’m overthinking this but once its built that’s it! So do you think I’ll be sacrificing much heat from the walls to the concrete slab if the fiber board is internal and butt up to the walls? Only reason I mentioned 4" is I have 2 boards 2"x24x36. If I butt them to the walls i could stack the two and have 4". Otherwise i had planned to lay them 36x48 and place the entire oven on top leaving and internal floor area of 24x36…plus an addition hearth entrance… so, what say you oven guru? :grin:

I don’t see any issues in this at all.

In fact, I like to have the walls of the oven on the concrete - not on the insulating panel.

Since the oven is 100’s of lbs (if not 1000+ lbs), it’s best to have it on concrete as the insulating panel is lightweight and fragile.

As for heating issues - there will not be any.

Thx -