Newbie question about oven floor

[Puckncrazy1]

I'm having an oven built for me and told the contractor that we need at least a 4" base of insulated concrete to set the firebricks on for the oven floor. That was not done, instead I have 2 layers of firebrick on a massive base of concrete filled, concrete block.
Will this design work? Will this oven ever get hot enough to use and will it maintain heat?

Thanks
Jay

[Laurentius]

You're paying him? Have him to build it right! Once its finish it too late too costly. Provide him with details of your insulated concrete mixture, the info is on the forum. You should check each phase of the build, these guy are experts but not in the field of WFO. You don't want to end up with a White Elephant.

[Tscarborough]

Remove the firebrick and put the insulation in.

[Faith In Virginia]

They make an insulation fire brick. Insulation brick can work fine. If it is the regular fire brick that is for the floor and dome. Stop him now and get some insulation under there.

[Puckncrazy1]

so... this is an unconventional oven... the oven will be sitting on a 4' solid cube of concrete plus the 6-8" slab it is sitting on. I had free concrete blocks so the whole base is concrete filled concrete blocks.
My guy thinks that the two layers of firebrick sitting on that massive chunk of concrete will maintain heat and thinks that insulation under the firebrick is for ovens that don't have this solid base like we have.
Thoughts?

[deejayoh]

The base will suck the heat out of the oven - and the bigger the base you have, the worse the problem will be. You want to direct all the heat from the fire into heating your firebrick. Without insulation, the heat gets dissipated into the slab, and you'll never be able to maintain a hot enough floor for cooking.

As others have said, get some insulation in there before you go any further.

[Puckncrazy1]

Will the 2" thick Alumina Silicate board be enough insulation between the firebrick and the solid base?

[shuboyje]

Fire the mason and get one who can listen to simple direct instructions from his customer. I work in large commercial construction for a living, if I ignored the direct request of the customer I would no longer have a job. That's the easiest part of construction, the guy with the money calls the shots. If you are an expert in your field you may sway their thoughts, but they still make the final call.

[RTflorida]

Pull up both layers of the firebrick , add the 2" board and then top it with one layer of firebrick. The 2" board is the equivelent of 4-5" of insulated concrete, you should then be fine.

Fire the idiot, if you leave it the way it is you will have the largest heat sink known to man. It would NEVER, EVER get up to temp and certainly not maintain a temp. He may me a fine mason, but he certainly is not an oven builder.

RT

[Neil2]

"My guy thinks that ...."

I second Shuboyje and RT. Get a new "guy".

If he is going to screw up and argue on this, He is likely to screw up and argue down the line.