Foundation Insulation?

[2000xpsd]

I just put a 32x48 foundation in the ground and am going to backfill soon...no floor until the spring tho. I don't know if I'm going to pex the floor yet but I figured I'd insulate the walls anyways. So what's the best way...I'm in MA and from the top of floor it's 16" to top of foundation:
1) insulation on the outside or inside of wall?

2) thickness?

3) how far down to insulate

4) is it even worth it?

 

[HoosierMark]

On my walkout basement they recommended I used 2 inch styrofoam against the inside of the frost wall (foundation) from the footer to the top. The concrete guy said it was important as it kept the cold from migrating in from the outside. The cost of 4 x 8 sheets is relatively inexpensive so you have very little to lose. If you are going to possibly heat the floor I would probably put even thicker in. Why not ask your pex guy for a recommendation. I am not a professional but a preventer, the insulation cannot hurt anything and can only help.

 

[ed_h]

Insulation on the outside puts the masonry on the heated side. The extra thermal mass tends to damp out temperature swings, stabilizing temps.

Don't know where you are, but in a place with winters, I'd take it all the way to the footing--deep ground temps are normally quite a bit below desirable room temp.

One issue with outside foundation insulation is what to do above grade. One good approach is to overhang the sill plate the thickness of the insulation and then apply a cementacious coating to the insulation.

 

[stigedis]

This is the exact question I have been pondering for some time. In MN where temps get really cold. Will be building28x40 stick built 2x6 in the spring. In floor heat. I know I want to insulate the foundation (no floating slab for this cat), But what will be the best approach to cover the foundation. I like the idea of keeping the cold out of the wall and think exterior wall insulation is superior to interior wall. I will have about 2-3 feet exposed at the back of the garage due to elevation change.
Question is if one hangs the sill plate over the exterior of the wall (say 1 1/2 or so to accomodate the insulation foam, and for sheeting to be even with insulation), wont the structure of the wall assembly be compromised as it will not be built on center of the foundation? Almost has sort of a tilting away feeling. I think certiform has impregnated wooden 1x2 in the foam to allow fastening of siding, then ground breaker or PT plywood for below siding to meet code.

What have other done to remedy the situation?
I may post this is heating/cooling forum as well.
Thanks..

 

[rancherbill]

1) insulation on the outside or inside of wall?
2) thickness?
3) how far down to insulate
4) is it even worth it?

1 outside
2 2"
3 top to bottom + cover the footing and extend a little more, make it 'L' shaped. Here is a pic along with other ways to do it depending on your specifics.
4 yes

 

[idoine in toronto]

don't forget to protect your foundation this winter.

 

[NUTTSGT]

One you get above grade, you can use something like this to insulate and still look nice.

http://www.menards.com/main/buildin...dation-insulation-panel/p-1458141-c-13074.htm

 

[ConCretin]

I'll take a run at your questions;

1) insulation on the outside or inside of wall? I prefer the inside. If you run it outside, you'll need to cover it if it's exposed to the weather.

2) thickness? 2" is typically fine

3) how far down to insulate? At a minimum, insulate from 4' below grade to the top of the slab.

4) is it even worth it? - Yes. It's very important to prevent frost from coming through your wall and freezing/heaving the soil under your slab.

Good luck with your project