Building in Central Florida, Question about insulation beneath cooking floor

[GianniFocaccia]

Re: Building in Central Florida, Question about insulation beneath cooking floor

I believe it has been noted here that perlite/vermiculite has the same insulating value as insulating firebrick (IFB). The 3" base of my oven-floor insulation is 8:1 vermiculite and although it took a small amount of work to install, it was an easy project. I topped this layer with 2" of Insblock 19.

For the same depth (4") you would need approximately 120 IFB vs two 4cuft bags (I paid $29 ea) of vermiculite to properly insulate the bottom of a 42" oven.

John

[glowthb]

Re: Building in Central Florida, Question about insulation beneath cooking floor

Thank you.

The K-23 here is $3.75 a brick, with Perlite at $35.00 for a 4 cu. foot bag the costs are relatively the same.

So the issue comes down to efficiency. K-23 vs. Perlite/cement.

[Tscarborough]

Re: Building in Central Florida, Question about insulation beneath cooking floor

The K-23 run about 9 bucks a pop here, while perlite is pretty cheap. They will work well, if you can afford it.

[Jed]

Re: Building in Central Florida, Question about insulation beneath cooking floor

Hi glowthb,

I don't have any experience with the light weight brick.

I can say the mixture detailed in the FB Pompeii plans, with four inches of perlite / cement mixture, works. It is a known and proven technology.... I'd stick with what is proven.

JED

[glowthb]

First let me say hello and thanks to all that post here...been learning alot.

I am getting ready to pour the hearth for my new brick oven but am looking at different options for the insulation beneath the cooking floor.

I have been able to locate large perlite at the local hydroponics store if I go with perlite/cement insulation medium.

Or I also found at a pottery supply center "Soft Straight K-23 Firebrick" that are used for insulating Kilns. They are the same size as fire brick, 9x4.5x2.5, but weigh only two pounds.

1. What are your thoughts on which is better for beneath the brick cooking floor?

2. If perlite cement mixture is used, how thick does it need to be? Looks like 4" according to the Pompei building guide.

3. Does anyone have any experience with the K-23 bricks?

Thanks.