Kiln Insulation?

WoodChucker · April 17, 2004, 07:43:17 AM

Hi all, I asked this in another thread but it sort of got lost in the BS, that stands for saw dust, ;D and never got answered.

Anyway, I need to know if it's OK to use the fiberglass rolls of insulation inside the walls and ceiling of my new kiln if I put the rigid foam over it with a VB? And should I use the rigid foam inside and outside of the studs?

I've heard people say to never use the fiberglass in a kiln because of the moister, but I'm not sure if it would matter as long as it was covered with the rigid stuff? Thanks!

R.T.

Norm · April 18, 2004, 06:23:01 AM

WC I've read and would agree that no matter how good your vapor barrier is that moisture will get into the fiberglass insulation. When I built our chamber I used rigid on the inside with poly and the outside of the walls sheated with it, nothing in between the studs. It is inside of a building so I didn't have to cover the outside layer of rigid insulation. Keeping the heat in has not been a big problem. Most times after getting the heat up the dh unit just running keeps it up to temp.

Don_Lewis · April 18, 2004, 06:56:41 AM

Rigid foam on the inside and fiberglass on the outside is okay if very carefully done. It is best used on low temp (below 120F/ 50C) kilns. Make sure there is a good vapor barrier, the inside is coated with an asphalt based coating and the seams are all caulked and sealed with asphalt and cloth.

shopteacher · April 18, 2004, 06:58:29 AM

I don't have a kiln yet, but do plan on putting some type of building together before summers end. Myself I plan on using only rigid insulation. Lowes carrys 2" thick insulation. I plan to double thick between the studs with either a sheet of 1" insulation or plywood covering that. I also intend to cover the inside of the building with sheetmetal to protect the walls. There's a large duct manufacture about a mile from me that has a dumpster full of scrap galvanized pieces every week.

WoodChucker · April 18, 2004, 06:59:48 AM

Thanks Norm_F, that's interesting, never even thought about being able to do it that way. What size was the rigid insulation that you used? And did you do the same thing for the ceiling? And did you run into any problems building the door doing it this way? Thanks for your input!

R.T.

WoodChucker · April 18, 2004, 07:09:36 AM

QuoteRigid foam on the inside and fiberglass on the outside is okay if very carefully done. It is best used on low temp (below 120F/ 50C) kilns. Make sure there is a good vapor barrier, the inside is coated with an asphalt based coating and the seams are all caulked and sealed with asphalt and cloth.

Hi Don, what type of cloth are you talking about? Never heard of that before. So if I needed to get the temp up in the kiln to set the pitch in pine to around 160 for a couple of days, I shouldn't use the fiberglass then, right? Thanks!

R.T.

Norm · April 18, 2004, 07:14:33 AM

If I had it to do all over again WC I'd have someone come in and spray on the insulation. Horselogger showed them doing his and it looked like a great idea.

Yes I used it on the ceiling also, and the door. It's 1" doubled on the outside and one layer on the inside. The door is still the weak point in my kiln. One big door or two smaller ones it's still hard to get them to seal. My door is one large one built with 2x2's and insulation on both sides.

Nyle has some good plans that they sell, mine came when I bought the unit.

WoodChucker · April 18, 2004, 07:31:05 AM

Yeah I tried to find someone around here that did that spray insulation and didn't have any luck so I gave up on the idea. Thanks for the info on the door. I can see where that would be the biggest problem area. I'll be getting the door kit from Nyle, is that what you used? Thanks again!

R.T.

shopteacher · April 18, 2004, 10:07:23 AM

here is a company that sell the foam in a kit
http://www.fomofoam.com/

WoodChucker · April 18, 2004, 11:01:15 AM

Thanks Shopteacher, that might be worth checking into. Appreciate the link!

R.T.

Norm · April 18, 2004, 01:43:33 PM

I just went to the hardware store and bought weatherstripping WC, it doesn't work very well. Brian Bailey spoke of using hot water pipe insulation, maybe he will see this and tell us how he does his door.

Don_Lewis · April 18, 2004, 04:31:19 PM

Two or three points. DON'T use galvanized metal inside the kiln. The zinc and acetic acid from the wood react. Plain steel lasts better than galvanized but that still isn't too good.

Be careful with the foam kits. While a professional installer can control the density and do multiple passes, the kits tend to make foam that is much too light and deteriorates. But a job by a competent pro is the best way to go if you can find one that hasn't been breathing too much of it

Can't remember the third point...I'll skim back through the posts

Don_Lewis · April 18, 2004, 04:33:48 PM

Right...the cloth. You can buy a roll of fiberglass cloth that lloks like bug screen. It is sold with the ashpalt roof patch. Trowel the asphalt into the joints and then press the cloth in and retrowel. Then put aluminized, fibered metal roof coating over the whole thing.

WoodChucker · April 18, 2004, 04:39:54 PM

OK Norm, thanks!

Don, thanks for the info, I won't be using any metal, just cdx plywood.

Is it better to go with 2x6 studs or is 2x4 enough? I'm thinking I might run into problems with the door if I used 2x6.

R.T.

Brian_Bailey · April 18, 2004, 06:51:08 PM

Foam pipe insulation works real good for sealing swing type doors.

All you have to do is make a wooden holder for the foam.
It's just a piece of lumber with a rabbet in it to compress and hold the foam.

Close your door and push the piece of wood with the foam in it up tight to the door. Make a mark on the wall/ceiling that will show where the back edge of the board is.
Now open the door and move the back edge of the board about 1/4" or so towards the door opening.
With stainless steel screws attach the holders to the wall and ceiling.
Push the foam pipe insulation into the rabbet and close the door for a nice sealed fit.
The size of the rabbet in the wood will depend on what size pipe insulation you use.
For 3/4" pipe insulation, which is what I use, the rabbet would be approx. 7/8" x 1 1/4". You could also just put two pieces of wood together to form the rabbet.

For the bottom of the door, I sized the door so there would be a 1/2" gap between the door and the floor. I take a section of pipe insulation and cut it in half lenght wise. I then push the half under the door for a nice snug fit.

3/4" pipe insulation comes in 6' sections and are very inexpensive.

I'm selling my kiln and buying a large freezer and refridgerator. Read on another forum that you can dry large chunks o' wood by freezing them for a couple of days then finishing em in the fridge for a week, oh boy I'm in the money now 8) ;D ;D.

WoodChucker · April 19, 2004, 01:01:48 AM

Brian_Bailey,

Wow, what a good idea! That really seems like it would work. Is the foam pipe insulation just held in place by a friction fit in the rabbit or does it need to be glued? Also, what is the physical size of the wood you put the rabbit in, like a 1"x2"? And does it become the door jam or will I still need a jam? Seems like that would act as the jam if I'm seeing it right. You wouldn't happen to have a pic of it would you? Anyway, thanks for your help and sharing your idea, I appreciate it! And thanks to Norm_F for bringing this up!

R.T.

Brian_Bailey · April 19, 2004, 07:13:17 AM

WC,

I would make it separate from your door construction.

All you need is, a piece of wood that you can cut the rabbet or two pieces put together to form the rabbet.

The size of the rabbet will depend on the size of pipe insulation you use. I prefer the 3/4" size.

It's nothing fancy as you want to be able to replace it easily if it gets damaged from moving lumber in/out of the kiln.

The insulation just friction fits into the rabbet, so it can easily be replaced.

You really don't want to see a picture of my setup because the way I described it is not the way I did it ??? :D.

When I first thought about using the pipe insulation, I wasn't sure if it would work.
So all I did was attach the pipe insulation with a strip of wood screwed down the center of the tube.
When you tighten the screws it flattens the tube and makes a tight seal against the door.

It has worked well for me, but looks like crap.

I've been going to redo the job as I described above, but it has been delegated to one of those get around to it jobs, if you know what I mean :D :D

WoodChucker · April 19, 2004, 04:19:25 PM

Yep, I know just what ya mean, I have a few of those "get to it when i can jobs" waiting in the wings, but I think I need a bigger hanger. ;D

OK thanks, I think I see what your saying and I'll play around with it. Appreciate the info!

R.T.

Ga_Boy · April 21, 2004, 10:41:32 AM

Don,

I've got a few question regarding spray foam insulation. These questions are in terms of use in a DH Kiln.

Which type spray foam is preferred, closed cell or open cell?

Is there a performance difference between the soy foam and the poly foam? Here again, is there a preference for which?

I want to remember there being a thread that discussed this but can't seem to find it. Any thoughts on this would be appreciated.

Mark