How to determine the Frost Line

[Henry Bowman]

This is probably basic, I know, but how do you determine the depth of the frost line?

:?:

[Rich]

Typically your local building department will tell you what they have determined the frost line to be. They will stipulate that a weight bearing footing or foundation is required to be xx" deep. In most parts of the country if you go 4' you will be plenty deep. I believe NAHB also has a chart for different states and what the depth is - but it's been awhile since I've been to their site.

[Sophist]

I live in Kamloops BC and there are different depths of frost lines within the city. Depending on what area of the city you live in the frost line changes.

This is due to the difference in elevation in various parts of the city.

I would talk to your local building inspector, they would know for sure.