Hi All:

First time back since the change.  Lots of lurking since then.

Here is the deal.  Building a new house – I am acting as GC.  Northern MN.  Knew we had some ledge rock from test holes I dug.  Excavated 3 days ago.  At most, I have 18″ of soil cover.  In some places, 1″.  Luckily the ledge is fairly level.  We cleared all the soil from the entire home site.  Am planning on a radiant slab (no basement) for the first floor. The house site sits on the high spot for 100s of feet around, so I should have good drainage (at least no water running towards house) – imagine a small knoll with a 100′ radius – that is our house site.  The ledge is not crumbly, but solid.  The usual grooves and small cracks here & there.

I have an architect and he has his opinion, but wanting to get other opinions, I wanted to throw out this question to this board to get responses:

Will I have frost heave problems if the exterior perimeter of the footer is not covered by enough soil to prevent freezing at the footer level? (In No. MN, this equals about 48″)

I am hoping the stem wall is can be just 24″ high (ICF), so at most, the footer would have 18″ of cover once I back fill, and most of that would be rock for drainage.   If my stem walls get much higher, the house will start to loom over the site.

I hope this is somewhat clear.   Essentially, do I have to worry that enough water will be able to penetrate between the ledge and footer to make mischief? 

The ledge rock will be swept & pressure washed before the footer gets poured.

I will have a good grade away from house, 2′ overhangs & gutters directing rain away.  I will also have drain tile around the perimeter, exiting to daylight on three sides.

Again, I will be ultimately  following the advice of my architect & mason, but just looking for discussion points….

Thanks….

Pinemarten