PDA

View Full Version : anyone try tigerfoam, or other spray foam



Andrew Jordan
08-22-2013, 2:26 PM
I have discovered an unvented attic full of sawdust above our bedroom - i've removed the sawdust, and discovered that it has gotten wet up there at one point! :(

We're now thinking about how to fix the attic to make it function better. My thought is to turn it into conditioned space, by putting XPS extruded polystyrene on the roof decking and sprayfoaming a skin over the top of that, to make it air tight. That way, I don't have to cut venting or put a vapor barrier on the ceiling side (there's none currently) into the roof (it's a fairly low-slope roof).

Can I sprayfoam over XPS? Anyone try the DIY sprayfoam option? I was going to have a company do it, but they heat their foam, and they can't spray over XPS...and I'm nto entirely keen on putting the sprayfoam directly on the roof decking, in case we need to replace boards down the line...

Andrew Jordan
08-23-2013, 11:42 AM
I would have guessed that one person would have tried sprayfoam...

Mel Fulks
08-23-2013, 12:11 PM
We have ALL tried it ,but not allowed to talk about it. Its image is tightly controlled by mfg. Sorry ,couldn't resist!. See if Forest Products Lab has tested it. Not everything they test is directly wood related.

Jerry Bruette
08-23-2013, 9:32 PM
Andrew

Are you going to get a high enough R value using the XPS with a skin of spray foam over it? I used a product called Touch N Seal two part foam and sprayed the sill boxes in my basement. It sealed the voids better than the fiberglass it replaced but was fairly messy to work with. The gun that came with the kit needed a mixing nozzle attached to it and the valve shut off at the end where the mixing started. That meant that when the trigger was released and the valve shut all the foam in the nozzle was expanding and oozing out. It dripped on everything and everywhere. You also get some rebound while spraying so you'll have to suit up in some old clothes with a hat and safety glasses or a pair of Tyvec coveralls and cover anything you don't want covered with little dots of foam. Oh ya you'll want to ventilate the space while you're spraying too.

Another consideration would be that the foam should be covered with fire rated drywall when you're done or the inspector/insurance company may not be happy with you.

Jerry

Andrew Jordan
08-23-2013, 11:08 PM
I was thinking that I could put 6" of XPS in the void - R30, with a one inch skin over the top of everything - another R6 - is that enough insulation?

I don't mind messy, as long as it works...

Jay Jolliffe
08-24-2013, 6:04 AM
I think I'd check the codes in the country you in. The codes in the states most likely are different.

Robert Maloney
08-26-2013, 4:07 PM
You should still vent the roof though. If you put the XPS and spray foam directly to the sheathing your going to have premature wear of your roof. Ideally the underside of the roof should be the same temp as outside. My brother has personally had to replace 30yr shingles after 10 years because the spray foam didn't allow the roof to breathe and baked the shingles. You can get around that by adding baffles between the rafters.

Erik Loza
08-26-2013, 4:18 PM
...the spray foam didn't allow the roof to breathe...

You know, I had this exact conversation with the GC who remodeled our house and his comments were the same as Robert's. ^^^

No firsthand experience with it but see it pretty often in DIY remodel shows, so I guess it is common but our contractor was pretty adamant about the fact that he didn't trust it in the long run. Do your own research, though.

Erik Loza
Minimax USA

Art Mulder
08-26-2013, 4:25 PM
No firsthand experience here either... I have watched/read a number of articles about using SIPs, and those obviously would not be vented when used as a roof. In that case you are supposed to use "high heat" shingles -- shingles specifically designed for this situation.

Mel Fulks
08-26-2013, 4:37 PM
Lot of different opinions on this stuff ESPECIALLY among the experts. I've got a cape cod with the knee wall and aaccess door to lower roof section ,it used to get 130 degrees in there. I bought 6 inch soffit vents, vented lower roof to upper section fan assisted. All that helped little. I closed off air flow from soffit to lower roof, removed fan, closed venting to upper roof and put fiber glass R19 insulation between rafters. Now the temperature in there never gets above ooutdoor temperature . No sign of any moisture problem etc. The roof color is the darkest green and that part of roof is FULL sun .
that was more than three years ago and electric bills are consistently lower.

Paul F Franklin
09-01-2013, 9:11 PM
I used Tiger foam to insulate the rim joist in my basement. You could spray it over XPS..it gets hot while it's curing but not that hot. I would not consider doing an attic myself unless you can stand up everywhere and have solid flooring everywhere. Why? The nozzle clogs if you stop spraying for more than about 20 - 30 seconds. Stop for longer than that and you have to change the nozzle (which is easy, and they are fairly cheap, but cost adds up). I had a friend help and all he did was keep moving the tanks (I had them on a cart) to keep up with me, but there were still several times when the nozzle clogged in the time it took me to climb down, move the ladder, and climb back up. You have to wear a full bunny suit, face mask, and respirator. The stuff blows back some and gets on everything. Blobs drip off the nozzles even when you stop spraying because the material in the mixing chamber expands even with the gun off, so you get blobs all over the floor. If I had to do it over again, I'd hire a pro. If you want to prevent the foam from sticking to the roof sheathing, maybe a thin sheet of foil faced urethane insulation board would take the heat from the commercial guns. HTH