Kiln wall material and insulation

What to use when you're building your own kiln. January 21, 2002

I'm building a 12 x 16 x 12 high kiln. I have the structure but need to put in walls and insulation. Any advice on the material I should use?

Forum Responses
I wood-framed with fibreglass insulation and ended up struggling for a while with vapour barriers.

I ended up tacking up Krona. (Other products of this type are usually polyethylene, which softens too much in the heat.) At first I couldn't find a tape that would seal it in the kiln environment. The 3M rep found me the stuff, though. 8951 is a tape for masking powdercoat or something, but it sticks tenaciously to the polyester surface of Krona and is unaffected by the heat and humidity.

You can get a guy to come in and blow polyurethane, which insulates and is a barrier too, but it costs a whack of dough.

I should add that, after foil tape failed on the Krona, I tried the Peel & Seal that Nyle sells. It is a 40 mil aluminum-faced asphaltic rubber made for low-slope roofing and such. It fell off the Krona, too. (Softens in the heat and pulls away.) Maybe it would seal other materials, but not the smooth polyester of Krona.

Polyurethane may not be the cheapest insulation, but considering its high R-value, I think it is a good value. It's also cheaper than rebuilding kilns every few years because of leaky vapor barriers allowing moisture to get to framing.

I had some pretty good luck using Ice and Water Shield™ (bituthene) as a vapor barrier over EPS foam board. I used both the standard and the high-temperature versions (the HT is much costlier) and saw no real difference in durability over a year of operation at temperatures averaging 130-150 degrees(F).

Will the Ice and Water Shield™ (bituthene) not eat away at the EPS foam board? I would think the solvents would dissolve it?

The bituthene still holds today. It is installed over thermax as well and still holds on that, too. If the adhesive ate at the styro, the bond didn't fail.

I am working on setting up a Nyle 200 now. We used fiberglass between the studs, 1 inch foam board, 6 mil plastic sheet then 1 inch pine lumber (so far). I am working on the doors now.