Fatal insulation error---I Fear.

[Derkp]

My dome/vault area is made of 4 1/2 inch firebrick, back wall also 4 1/2 inch, floor 4 1/2 inch. I applied about 3/4 inch of mortar over the vault to lock it all together.

My concern is that I have just finished my house enclosure, 2 X 4 walls, and there is only about 4 inches between the outer oven surface and the closest 2X4 edge. I plan on filling the total area, wall cavity and 4 inch space with perlite.

I have a thermocouple on the top, back wall, and under the floor. I am going to get a hot fire going before I do the roof and see what happens.

Will the 2X4s burn?

[echopark]

I have 2" of cerra-blanket over my dome and the hottest it's ever gotten on the outside is 100-degrees-F; but then my dome is not enclosed. You might want to consider metal studs for the roof -- I know of one oven who's wood roof burned off, now it's got a steel one. Good luck!

[Derkp]

The closest the 2X4 roof will get to the oven roof is 6 inches up to about 12 inches away.

Tomorrow will be the big burn and we will see hot hot it gets.

Thanks

[Tscarborough]

The ignition temperature of wood is pretty high (500F+), I do not think you will have a problem. As an example, fireplace clearances are usually 4" on the sides, and that is for exposed flame.

[Derkp]

Thanks Tom,

I was hoping that I would not have to track down some insulating blanket or something. There will be quite a bit of perlite on the sides and top. I remember seeing your photo and the big amount that you needed. The space does not look that big until you start to fill it.

Thanks

[texassourdough]

I would suggest using steel 2x4s. And sheathing it with hardiplank or equivalent. That way you have no concerns. (NOTE: I don't think it is likely to be a problem but...
Jay

[Derkp]

I have a piece of hardibacker left over from a tile job and I think that I will put pieces of it in between the 2X4 edge and layers of perlite. I found perlite for $8.60 per 4 cu/ft so I am going to lay it on heavy.