I have been reading alot about Frost Protected Shallow foundations and have a few questions I was hoping someoen could halp out with.  I am in an part of canada that calls for at least 4 feet frost coverage more in some areas and have heard about this method of building.  I have several crwls spaces and walkout basement houses lined up and was considering using this method.  Is this a viable alternative to using piles or would I still need piles to keep a shallow dig?  Is this dependant on soil conditions any more than a normal footing? I would like some more feed back from people who use this method as to its effectiveness.
Thanks
N

I have done the shallow footing and insulated out from the foundation as required. Honestly I did not like it since the footing was only 12" below finished grade 4" foam was placed on toip of that and extended 4' out from the foundation wall, fill was placed back on top. What I didn't like was how the landscape would be done with the foam so close to the horizontal surface.

My attitude is if you can dig it, dig it right.

Another question about FPSF. I live in Maryland and am considering this type of foundation (such as legalett) for a one story home with ICF walls. As most of the homes in this area are basement foundations which offer inherent freeze protection for utility lines, I am wondering how the utilities under the slab are protected from freezing, especially the water and sewer lines which must come up through the slab. Since 1 foot below the slab is still a potentially frost area, how are they protected from freezing?

Thanks
JW

We did a FPSF and it went quite well and ended looking fine. I think I would prefer it to a crawlspace, but just doing a stem wall backfilled on both sides is probably just as easy.

As long as the soil 16" - 18" below grade is decent and not disturbed, you should be ok without piles. The piles are needed if the bearing pressure at your footing levels are not adequate. Bearing Capacity tests are fairly inexpensive.

Here are a couple of videos showing how we did a FPSF with integrated radiant heating. The only thing not show is how we treated the exterior of the slab. For this we put a plastic vapor barrier, 2" of Polyiso insulation, wire mesh and then parged the wire with a stucco mortar mix. In MA we are required to insulate not only the exterior of the slab, but also 3' out horizontally from the bottom of the slab. If you have a copy of the IRC building code book it shows this. We not only insulated out from the slab but under the entire slab with 3" of Geofoam, a high density EPS designed for this purpose and has an R-value of 15.5
http://www.youtube.com/watch?v=J7ICP024ogw&feature=channel_page
http://www.youtube.com/watch?v=JkXceHPU7zw&feature=channel_page

Tom Pittsley
[email protected]
www.eebt.org

NAHB Research Center has a Design Guide for Frost -Protected Shallow Foundations that will give you all you need to know on the subject. We have used them with great success.