How Deep Should Fence Posts Be in Canada? Frost Line Guide by Province
How Deep Should Fence Posts Be in Canada?
The #1 cause of leaning fences in Canada is posts above the frost line.
Frost Line by Province
- BC (coastal): 45-60 cm
- BC (interior): 75-120 cm
- Alberta: 120-150 cm
- Saskatchewan: 120-150 cm
- Manitoba: 120-150 cm
- Ontario: 120 cm
- Quebec: 120-165 cm
The Rule: 15 cm Below Frost Line
For a 6-foot fence in Alberta: 180 cm above ground + 135 cm below = 315 cm total post length.
Prevent Frost Heave
- Dig bell-shaped holes (wider at bottom)
- 15 cm gravel at bottom for drainage
- Always use concrete
- Consider steel posts — smooth surface resists frost grip