Basement Finishing Question - Upper Midwest

[GarageLogic]

I know there are several threads on this here, and all over the internet, but I can't seem to find a definitive answer on how to insulate the block walls for a basement workshop/living area. Even the local codes are vague. Location is the Twin Cities, MN.

Thinking about gluing rigid foam panels to the block wall, then framing 2x4 walls, and placing kraft-faced insulation batts between the studs.

Two questions:

1) is the above a correct method that won't require a separate vapor barrier?

2) what kind of rigid foam panels - the 'pink' kind or the one with foil on one side.

Actually 3 questions I guess - how thick should the foam panels be? Basement is fairly warm in it's unfinished state, with no vents currently installed, so I don't think I have to go with a super high R value.

 

[dfiler2]

I think this is the best method. http://www.insofast.com/ Keep in mind this is only my opinion.

 

[Milzo]

Never seen insofast before cool product

 

[theoldwizard1]

If you are going to make stud walls, you can just press the foam between the studs. Cutting rigid foam to fit between the floor joist up against the rim joists and then foaming around it is also a good idea. After the foam board is secure with foam, you can loosely pack it with fiberglass insulation.

Be sure the bottom plate is pressure treated lumber because it will contact the concrete floor. You might even want "weep hole" so that any moisture that accumulates behind can drain out.

The BEST thing you can do to help make a basement more comfortable, is installed a raised subfloor. These are usually 2'x2' square with some type of plastic dimples that raise them off of the concrete. They are kind of a pain to install level (because your floor is not level), but what ever floor covering you choose, will be a lot warmer. Also, any minor wall leaks will simply find their way to the drain and your finished floor will be dry !

 

[theoldwizard1]

I think this is the best method. http://www.insofast.com/

Looks good ! I don't think R10 is adequate for wall insulation in MN where the frost line will go down 4' ! I'll bet it is $$$$ !

 

[dfiler2]

Looks good ! I don't think R10 is adequate for wall insulation in MN where the frost line will go down 4' ! I'll bet it is $$$$ !

We get 4' of frost only when it is a really mild winter, I'm located in the NW corner about 20 miles from Canada. What I've found in basements is that just about any thermal break really helps. Keep in mind the surface temp of the ground never drops below 18 above and 8' feet down it is usually still in that 45 degree range. The method you suggested is a good one and works well, I've done quite a few basements like that. I found the above product a few years ago when I was ready to finish my basement, it does cost more and I don't remember exactly how much but I don't think it was all that much. I liked the fact that it gave me a pretty good thermal break for the entire thickness. One thing I really like about it is how much cleaner it is, no sawing and drilling concrete in the basement.

 

[jvitez]

I'm north of you so colder (-27°C this am), but our basement insulation spec is R20 minimum. I did R24, by having a 2x4 sud wall built 3.5" away from the foundation wall. R12 fibreglass insulation was installed horizontally behind the stud wall creating a thermal break, and R12 batts were installed vertically in the stud bays with 6 mil poly vapour barrier/acoustical sealant/Tuck tape over top.

If it's a block wall, is it fully water tight? Make sure you fix any moisture problems first. But gluing rigid foam with a stud wall touching the foam will also give a thermal break, and less worry if there is any moisture.

http://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers

You're in zone 6, so you need a Class II vapour retarder on the warm-in-winter, ie inside of the stud wall.

 

[theoldwizard1]

We get 4' of frost only when it is a really mild winter, I'm located in the NW corner about 20 miles from Canada.

I'm with you this weekend brother ! Tomorrow mornings low is supposed to be -10F, before the wind chill.

 

[JOHN 86GT]

http://www.homeconstructionimprovement.com/how-to-insulate-basement-walls/

I like un faced insulation and separate poly vapor barrier.

If I did over , I'd stud away from the wall (2x6 top and bottom plate ) and use spray foam

 

[Rossco]

Iam gonna do the rest of my Basement with Owens Corning XPS @ 1" then 2x4 Baton with vapour barrier for good measure.

I have these to secure the foam to the walls. I will use a tube of adhesive as well.

Plenty of Expanding foam to seal & Tuck tape.

Should give me R5 + R12 = R17 + What ever the the drywall is.

 

[jdieter]

Just finished my northern Indiana basement remodel. Used 2" closed cell spray foam on the walls all the way to the rim joist, then metal studs and drywall. Used 1/2" foam board with 3/4" plywood on the floor. Basement originally had batt insulation and wood studs. The comfort and reduced heating cost is unbelievable.

 

[earthworks]

You should heed jvitez's remarks about insuring no water problems before installing any vapor retarder. And I definitely think best practise is to use eps then 2x4 stud walls with r13 batting then poly vapor barrier. But I'm north of you just over the Canadian border and have framed out several basements with just 2x4s and batting and 6mil poly and have found it very comfortable and sufficient. Also inexpensive and quick. Remember..poly inside warm space, and it is the most important part of envelope. Tape the seams don't just overlap, and be thorough with acoustical sealant. Any holes will allow air to pass through and thus heat loss and moisture build up leading to mold.
Also the 2x2 osb subfloor tools are the fastest and best way to go..they allow the floor to circulate air and remain dry and warm.