Had to pick between a standard and a frost-protected shallow foundation for my garage add-on

I was planning my garage addition here in Edmonton and the big choice was how deep to dig the footings. My contractor said we could go with the usual 4-foot depth to get below the frost line, or try a frost-protected shallow foundation that only needs 16 inches but needs special insulation. I went with the shallow one to save on digging costs and time, and it passed inspection last week. Has anyone else in the city used this method for a smaller project and how did it hold up over a winter?

3 comments

3 Comments

grantadams1mo agoMost Upvoted

Good call saving the digging cost, that frost line is brutal here. The insulation detail is key, you have to make sure it wraps the footing properly to stop that ground heat from escaping. My neighbor's shed has held up fine for three winters on a similar setup.

hannahs451mo ago

Yeah, wrapping that insulation right is the whole game. I used two-inch rigid foam board around my footing and up the stem wall, then taped all the seams with that heavy-duty foil tape. No heaving after two nasty winters, so it seems to be doing its job. Did you go with the foam board or something else?

william_carter1mo ago

Honestly, I was a spray foam guy before this.