Question - Foam Insulation

[cjbenedict]

Hi, I'm renovating a room in my basement and plan to put up foam sheets against the foundation before the frame & more insulation. For around the foam boards and for up between the floor joists does it matter what kind of spray insulation foam I use? Is the cans of foam from Canadian Tire & Rona good enough for this, or is there another product out there that is more appropriate?

Thanks for any help.

[astroboi]

For such large jobs you'd be better off buying the large tubs from Home Depot that come with a spray gun.

[Drthorne]

those cans will do, but you'll need a few of them. get the low expanding type since you don't want it bulging out too far from the wall. Tuck tape will be good enough where the factory edge on the foam boards butt up against each other. What thickness of foam board are you installing?

[cjbenedict]

From what I've read so far a good way to go is with a two inch foam board against the foundation leaving a 1/4" on each side. Tuck tape all the seams and use the bottle foam to fill the 1/4" gap around the outside. Then put your studs & insulation in front of that. The foam boards act as a vapor barrier so you don't need the 6 mil poly.

My question for the expanding foam is about it expanding and contracting with the heat/cold. Will it matter which kind I use (ie. Rona-brand, 'Great Stuff', etc...)? Or are there brands out there that don't expand-contract as much?

Cheers

[Cheap Cat]

From what I've read so far a good way to go is with a two inch foam board against the foundation leaving a 1/4" on each side. Tuck tape all the seams and use the bottle foam to fill the 1/4" gap around the outside. Then put your studs & insulation in front of that. The foam boards act as a vapor barrier so you don't need the 6 mil poly.

My question for the expanding foam is about it expanding and contracting with the heat/cold. Will it matter which kind I use (ie. Rona-brand, 'Great Stuff', etc...)? Or are there brands out there that don't expand-contract as much?

Cheers

It's called expanding foam because it expands to fill the void and becomes a permanent, airtight seal. It does not contract. Generally you use the low expanding foam for voids/gaps under 2 inches and the regular for larger voids. Read the directions on the can as it can be messy to use for first timers. Make sure you only fill the void/gap 50% full as it will expand.

[issy]

what sort of framing are you doing for your basement?

i have just started one wall of my basement , using 2"x3" steel track with
2"x3" wood studs ...having anchor one to concrete floor and the other to good truss / beams.... this works great for me ..

i am not installation my basment wall with form ,like you , trying to stick to the old ways ...........my basement walls are pretty rough ( new house )

[cjbenedict]

what sort of framing are you doing for your basement?

i have just started one wall of my basement , using 2"x3" steel track with
2"x3" wood studs ...having anchor one to concrete floor and the other to good truss / beams.... this works great for me ..

i am not installation my basment wall with form ,like you , trying to stick to the old ways ...........my basement walls are pretty rough ( new house )

I like the idea of using the 2" foam boards as a vapor barrier because it provides R10+ insulation along with a vapor barrier. I haven't worked out the cost of the boards vs. 6 mil poly, but I would guess that the cost difference wouldn't be huge, plus the foam boards will pay for themselves in heating costs eventually...

Steel for the wall frame? From what I've read so far there's a few things to maybe keep in mind. Although metal won't rot, it will rust, so you don't want it touching anything that can have moisture (ie. concrete). For the bottom of the frame you might want to put down a foam strip between the concrete & steel track and then bolt it to the concrete.

Also, metal conducts heat and cold very well, so perhaps you may not want to use steel track for an outside wall. Wood won't conduct the cold/heat, and if you put a foam strip between it and the ground then water rotting it isn't a problem. The foam boards also keep moisture from the wooden studs, so it has another use...

As for the stud frame, I'm going with wood 2x4 in front of the foam boards, with a strip of foam between the wood & concrete. I'd go 2x6 for extra insulation, but it would probably be over-kill because I'm only doing one room in the basement and the rest is 40-year old insulation.

I've been told to consider the green insulation wool product (I forget it's name) in both the walls and in between the floor joists. It resists mold better than the pink, it will keep its shape even if soaked with water, it has a fire resistance, and also acts as a sound barrier from the floor above. A friend of the family said that because it has more structure it will hold itself between the floor joists without anything holding it there, and that is useful to me because I can hear my dad's tv clearly through the floor as it is...

[cjbenedict]

Oh yeah, as a bonus the foam boards against the foundation create an even surface for your frame, so you don't have drafty gaps :D