Questions about wood base fire safety

[Jumbalaya]

Hi,
I'm building a movable cast oven on a wood base. Essentially the bed will be a box made of 2"x6" (or 2"x4")lumber with a plywood bottom sitting on a wooden stand. The box will be filled with perlicrete (ceramic board is too expensive) then 50/50 sand/clay for leveling then 1 1/4" thick firebrick (under the oven only) then the 28" cast oven on top. The firebrick floor will be level with the top of the wood box.
-Can anyone comment on minimum thickness of perlicrete and clearance around oven to wood to make this base safe in terms of fire safety and efficiency?
-Would it be better to add a cutout sheet of Durock shaped like the oven over the perlicrete layer?
-How thin should sand/clay layer be for leveling?
Thx,
Jumbalaya

[dakzaag]

2X6 is not enough depth for pericrete. 2X10 may be pushing it. Since you are using half brick for the floor, you have half the mass protecting the support structure. Just remember, the unwanted fire will ignite well after the fire is down inside the oven. Like 3-4 am when you are passed out in bed. Build the base with masonry and sleep soundly.

[Toomulla]

A couple of observations. Firstly you mention the oven being moveable, the pericrete is not structural and I expect the assembly will break apart when you try and move it, you have not stated what will actually support the structure other then "a wooden stand" ,a concrete slab of reinforced concrete with 4 inches of pericrete under the oven would I believe perform better.. secondly should you go as you describe the risk of a fire is there, although six inches of pericrete should provide sufficient insulation as most ovens have less then that over the dome and do not usually get hot to the touch

[Jumbalaya]

The perlicrete would be contained in the box I mention in my initial post so it doesn't need strength. To illustrate what it will look like here is a video of a similar stand design...

[Jumbalaya]

Thanks Dakzaag I'm thinking maybe to be safe I will take your advice and build the box out of Durock board fill with perlicrete and only make the legs out of lumber.

[dakzaag]

Brace it well, the Durock will not burn, but it can transmit heat to the wood a layer of Al. flashing between the Durock and wood is cheap insurance. Pericrete is about half the insulation value of ceramic fiber board or Cal sil so if you wanted 4" of Cal sil you would need 8" of Pericrete. Again think safety first, Code is 12" from firebox so don't be setting this thing on a wooden deck.