Insulation depth for garage perimeter?

[UpNorther]

Pole Barn is up, and just starting to dig trenches for 2" foam around outside perimeter. I live in central Minnesota so frost can get deep some years.

How deep should I go ?

I was thinking 2 ft. Only reason is I know people that went 16" and they wish they had more.

 

[fastjohnny]

Either 2 feet down then 2 feet out, or ~4 feet down (to frost depth)

 

[K'ledgeBldr]

Frost line for your region is 55"-60".
I don't think 2' is going to do squat- I'd go at least 4'. Going out horizontally does make a considerable difference, but I don't see you doing that much digging.

 

[Jon_E]

Here in VT I insulated the inside of my frost walls, to 4' depth. 2" foam board, glued to the concrete.

 

[Dragfluid]

ANYTHING that you put down there is going to make a difference.
I put 2" 24" down on the outside. I'm 140 miles south of you.
Use cap nails to secure it to your rim board.

 

[bedn0009]

I built in Western Wisconsin, just outside of Minneapolis, and I went vertically 16" down the face of the "footing" and then at about 12" down I put 4 x 8' pieces of 2" foam around the entire perimeter.

Look up Frost Protected Shallow Foundation.

The entire garage feels very comfortable at all times - and I only put up a gas unit heater. It's much more comfortable than even my attached garage.