I live in Michigan with a Air-Freezing index of 2000.

On a insulated footing the ICC code book calls for 14 inches of insulation at R-5.6

So the way I see it one 16 inch deep ICF block under ground would satisfy the code so you don't have to go to the normal 42 inches?

Has anyone done this, or comments to this?

Thanks

Sounds like you want to do a frost protected shallow foundation vs a traditional one. There are specs for both.

I believe the code calls for the 14" to be horizontal @ 90 degrees to the outside of the wall.

Polycrete Big Block comes fully assembled up to 24" core size and up to 36" knocked down. These sizes are often used for footings.

Posted By FBBP on 29 May 2015 04:29 PM
I believe the code calls for the 14" to be horizontal @ 90 degrees to the outside of the wall.

In my area no horizontal insulation is required. Though I do think it is a good idea.

We are building a full walkout on a hill and thinking about using ICF as an insulated footing. This would save two courses of block over 180 ft, so a significant savings.

I am kind of questioning the temperature gradients through the wall being that ICF has insulation on both sides and an insulated footing has it only on one side.

I am guessing the insulated footing method keeps the heat inside the envelope not allowing the ground around the footing to freeze. Would this still be the case with ICF? Thanks.....and happy building....

Vertical insulation (as in ICF) does not prevent frost heave. Frost penetrates at a roughly a 45 degree angle. If you are trying to substitute frost protected shallow foundation for deep frost protection, you need to place the insulation horizontally out from the wall you are trying to protect.
So in your case with the requirement of 42" of frost protection, draw a line on a 45 degree angle from 42" below the surface away from the foundation. This is the area that needs to be protected. The deeper you are the less horizontal insulation you need. As you get to the surface, you will need insulation about 42" out from the foundation wall.

If the frost has to start its trip down at 42" away fro the foundation, the frost ball will still be outside of the foundation line when it penetrates to its maximum depth of 42".
If you do t the way you describe, as the frost penetrates the soil, it only needs to go down 16" to bypass your ICF block. After that the soils under the footing still freeze and cause frost heaving which will damage your foundation and house.

The are lots of articles on Frost Protected Shallow Foundations (FPSF) on the web. You need to take some time to study them so you understand the intent of what you are planning to do.
Some FPSF count on heat loss from the building to counteract the frost's penetration. Therefore you can not insulate your basement floor (or insulate it as much) Others bring the horizontal insulation out far enough so the the geothermal action of the earth prevent the frost form damaging the foundation. In these cases, you can fully insulate the basement floor slab, which is what you should be doing.

We recommend 2 courses of ICF (32") and a 10" footing. It seems to be the most efficient for time, cost, labor and inspectors.

Posted By emmetbrick on 15 Jun 2015 07:46 AM
We recommend 2 courses of ICF (32") and a 10" footing. It seems to be the most efficient for time, cost, labor and inspectors.

We do this a lot as well. It just gets the bottom of your footing itself down to 42".
Two out of three of the last three homes we built in Michigan were SFPF. These are slab on grade with a turned down foundation edge ,which  in much of the southern part of Michigan does not require the horizontal foam outside of the footing area.
 Don't skip the horizontal foam too many advantages.
The biggest is that frost or water are directed away from the foundation, much the same way a umbrella directs rain away. We use horizontal foam anywhere we can for that reason. You can actually water proof many basements this way. We did this on the Michigan EarthShip. It has 9' ICF walls with a 7' berm.  Platon was attached to the outside of the ICF and Horizontal foam and horizontal platon were place just below the topsoil, keeping the icf warm and dry.