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ACR_SCOUT 12-24-2011 09:23 PM

DIY spray foam
 
Hello all,
I have a 24" cantilever floor off the back of my house. I have taken the time to block it all out with 2" rigid foam board. So there is foam against the outside wall and the bottom.

I was thinking of getting one of those DIY foam kits to spray all the joints. At the same time I could spray the rim joists and seal them.

Do you think they are worth it? I've tried to use can spray but the cantilever is too tight.

Thanks.
Fred

forresth 12-24-2011 10:17 PM

you might try cutting your foam just a little bit big, then squeeze it in to eliminate air gaps.

joecaption 12-24-2011 11:14 PM

It would have had more R value to have added R-19 craft faced fiberglass with the paper toward the floors and added a piece of 1/2 plywood.
In fact that's code in most areas on a bay, bow window or a bump out.

ACR_SCOUT 12-25-2011 07:30 AM

Quote:

Originally Posted by joecaption
It would have had more R value to have added R-19 craft faced fiberglass with the paper toward the floors and added a piece of 1/2 plywood.
In fact that's code in most areas on a bay, bow window or a bump out.

Interesting. I did most of the work from inside the basement. I took out all the fiberglass insulation. I read on the net that using batt insulation lets too much air move around. Hence the foam board.

So back to the question, has anyone used the spray foam kits?

Thanks,
Fred

gma2rjc 12-28-2011 08:02 PM

I've used it once. It was easy to use and did a good job. It's a little pricey, but if I understand what you're talking about, you may only need the smaller cans of it. I think it would be worth every penny since it will make everything air tight.

MLMIB 12-28-2011 11:09 PM

you do need to be careful to not over do it in one shot as the foam will expand with pressure and could move/ruin the stuff around it. Also, if you're using the cans of great stuff get the ones made for window's if you are worried about pressure

user1007 12-29-2011 06:33 AM

Just remember open foam whether board or from spray can is not fire rating approved. Stuff ignites and melts and dangerous temps. You need to seal it with a firewall material.

That said, the canned stuff works alright for sealing spaces but depending on how much you have and your ability to be patient? You might see if the guys with foam insulation equipment but add your little project to the end of a bigger job in your hood.

ACR_SCOUT 12-29-2011 11:33 PM

Quote:

Originally Posted by sdsester (Post 806240)
Just remember open foam whether board or from spray can is not fire rating approved. Stuff ignites and melts and dangerous temps. You need to seal it with a firewall material.

That said, the canned stuff works alright for sealing spaces but depending on how much you have and your ability to be patient? You might see if the guys with foam insulation equipment but add your little project to the end of a bigger job in your hood.

Thank you. I have known it should be covered but I am a one man band so time is not on my side. Is this an acceptable risk? I can't really say other than there is nothing down there to start a fire right now.

Snav 12-30-2011 12:31 AM

Airkrete is the only fire-retardant insulative foam that I'm aware of . . . it's also mold resistant which I think would be a bonus in your application. . . if you're concerned about it.

ACR_SCOUT 12-30-2011 12:33 AM

Quote:

Originally Posted by Snav
Airkrete is the only fire-retardant insulative foam that I'm aware of . . . it's also mold resistant which I think would be a bonus in your application. . . if you're concerned about it.

Eventually it will be drywalled in when I finish my basement.

user1007 12-30-2011 05:35 AM

Quote:

Originally Posted by ACR_SCOUT (Post 806997)
Thank you. I have known it should be covered but I am a one man band so time is not on my side. Is this an acceptable risk? I can't really say other than there is nothing down there to start a fire right now.

Your insurance carrier or local inspector, if you are prone to having this work approved, may force your hand on this. You should find the time to make this safe. You may void your fire insurance policy if you do not.

And sneak in and ask a firefighter someday how many fires he/she has fought with starting points that supposedly had nothing that could start on fire. Sounds like the house in CT that went up recently was ignited by an external ember that blew into the house. Three little girls and their grandparents are gone if I heard the story right?

Guy four doors away from me destroyed a beautiful corner living space three or so Saturday nights ago and crispy crittered himself in the process. He fell asleep with a cigarette in hand and started a fire with the highly flammable sofa fabric and foam cushioning. Hall smells awful and the smoke damage was extensive. The building is doing battle with the insurance carrier over how much will be covered. The guy disabled smoke detectors between routine building checks. Should the building have known?

The unit was gone before the hall units detected smoke which was intense enough to have my detectors singing for 45 minutes or so even doors away and a towel blocking the gap at the bottom of the door. Fire department had the fire out in 15-20 minutes and the place only burned for not much more than that. All of it burned though, near instantly, thanks to non fire rated upholstery foam as the starting point. Thankfully all the firewall stuff---including drywall over foam insulation---worked perfectly. Only actual damage save for the smoke to any of us near was water into the two spaces below. Carpeting on this floor, almost brand new, is going to have to be replaced and everything scrubbed for smoke damage, primed and painted.

Sure you cannot make time to seal this foam project?

ACR_SCOUT 12-30-2011 07:56 AM

Quote:

Originally Posted by sdsester

Sure you cannot make time to seal this foam project?

S:

I understand where going and certainly appreciate your concern.

I hadn't thought of the insurance angle. Yikes. Another point you make me think about is toxic smoke that may decompasitate people in the house. Further, the extra insulation leaning against the wall down the is not likely a good idea. I need a shed.

Thanks.

Windows on Wash 12-30-2011 07:57 AM

Quote:

Originally Posted by ACR_SCOUT (Post 807047)
Eventually it will be drywalled in when I finish my basement.

+1 to sdester's comments.

Get it covered with a proper thermal barrier asap.

Foam is not going to spontaneously combust, however it does produce a bunch of bad stuff when it burns.


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