spray foam on a kiln wall ?

[Tom L]

will the spray in foam insulation work on the walls , floor, sealing, insulation on a kiln.
I see everyone is using fiberglass,
one company sells these spray foam insulation kits, so you can self instal

any problems with this?

[Brad_S.]

I used spray foam for my walls and ceiling. I didn't know much about it going into it so I trusted the contractor. He sold me on an open cell foam (cheaper) with a reflective vapor barrier. BIG mistake!

Moisture worked its way through the barrier and the open cell foam soaked it up like a sponge. When it came time to insulate my workshop I knew enough to use a closed cell foam on any wall that may see moisture.

I used a concrete floor with 2" blue board foam underneath. 

 

[BBTom]

Spray foam works great--IF-- you use 2.2 lb/cuft foam.  The foam that is used in home construction will absorb the moisture,  the industrial weight does not.  Some places call it 2.2 lb- others call it 2.5 lb.  I got Mooney and Moses, an Ohio insulation company to come and spray mine.  It is not cheap, but it is almost care free and absolutely sealed.  My 15' x 30' x 9' kiln cost about $3000 for 4" all 6 sides.  I am very pleased with it.
 

[xlogger]

Brad_S. I like the door you have on your kiln. What do you use to open it?

[LeeB]

Do a google search on spray foam kits. Several manufacturers and mostly close to the same price. Good information on most of the sites. Closed cell is more expensive per coverage (measured in board ft beleive it or not), but nearly twice as effective so not that much cost for the r-value, and should be used in high moisture applications.

[Brad_S.]

I have since gotten out of the sawing business and no longer have this set-up, but the kiln was located inside a 40x100 barn that housed my operation. The door was raised by an electric winch secured to one of the roof trusses.

BTW, what I didn't make clear in my previous post was that I am a huge fan of foam insulation, just be sure to use the right foam in the right application. For a kiln, closed cell foam, which I believe is the same stuff BBTom was refering to, is used whenever water or heavy water vapor will be present and is a must for a kiln. Closed cell foam also adds structural rigidity whereas open cell, not so much. Like BBTom, I filled the whole cavity but they say that only the first 2" is the really effective layer, additional inches add very marginal value. Like Lee said, foam insulating is priced by the boardfoot so if you figure out the bdft contained within the walls you want to fill, you can get a rough estimate of what it will cost. When I had my barn done 2 years ago, I believe the price was $2.65 per bdft. (The contractor loved the fact that I understood bdft pricing!)

I too looked into the DYI foam kits but when I added the expenses of the DYI vs. professionally installed, there was a negligable savings. The kit also seemed problematic...stop spraying for just a few seconds and the nozzle would plug up IIRC.

[Firewood dealer]

I have 3"of closed cell foam inside my firewood kiln and it works great. the temp. inside the kiln vessel runs around 250 deg. f. and you can lay your hand on the outside and it is cool.

[Tom L]

250 degrees is hot, how do you heat your kiln?

[Firewood dealer]

Wood waste from the processor. It gets fed into a firebox by conveyor. The firebox temp runs around 1100 deg. the hot air goes up through a heat exchanger and 4 fans circulate the hot air in the kiln vessel. When the wood is almost done, the supply temp. will be around 250 and the return will be around 210.

[Tom L]

so it is basically a forced air unit with a heat exchanger inside the firebox and you pump air in and out of the kiln to supply the hot air. that is a pretty neat idea. I bet the exchanger is some type of stainless steel so it takes the heat.

[GeneWengert-WoodDoc]

There are many softwood kilns that do not use a heat exchanger at all.  The wood is able to accept a low humidity.  For hardwoods, we need the exchanger in order to prevent low humidities--with an exchanger, you can recirrculate the hot air int he kiln, thereby keeping the humidity as high as you need it.