Insulatiing detached garage foundation

[stigedis]

Insulating detached garage foundation

In MN where temps get really cold. Will be building 28x40 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), will 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 othes done to remedy the situation?
Thanks..

 

[Randy in Maine]

I just insulated the inside of the foundation stem walls with 2" of foam. Then 2" of foam under the slab. You just want a thermal break between the heated floor and the unheated wall.

 

[anthony666]

take a look at this, you might find it interesting

http://webhotel2.tut.fi/nsb2011/sites/webhotel2.tut.fi.nsb2011/files/a4_04_airaksinen_heikkinen.pdf

 

[Steve in Mi]

On my 2 story 28' X 48' I used 1" Dow rigid foam inside the block foundation walls and under entire floor plus 1" foam on the exterior foundation walls that continues to the peak of the building. Where the foam would otherwise be exposed between the ground level and below the exterior siding I covered it with painted aluminum flashing. R-19 in the 2" X 6" stud walls and trusses on 16" centers. I insulated as if I would use in-floor heat but use GFA to heat it 24/7 in the months cooler than ~ 63 degrees. That's about six months where I live and I estimate $150. for last Winters heat. My concrete floor only lags the set point temp by a couple of degrees. I use a man door frequently almost daily but the overhead and double 6' doors seldom get used. 6 windows (all small) are triple pane casement. I'm extremely pleased with my 1982 shop build.