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Standard Foundation Depth
Standard foundation depths and footings for different structures
Standard Dimensions
| Size | Width | Length | Thickness | Notes |
|---|---|---|---|---|
| Frost Line Footing | 12-16 in | 6-8 in | 36-48 inches | Below frost line depth varies by location |
| Monolithic Slab Footing | 12-16 in | 6-8 in | 4-6 inches | Thickened edge of slab on grade |
| Sonotube Footing | 8-10 in | 8-10 in | 48-60 inches | Circular pier for deck or support post |
Frost Line Footing
Width Range
12 - 16 in
Length Range
6 - 8 in
Thickness
36 - 48 inches
Below frost line depth varies by location
Monolithic Slab Footing
Width Range
12 - 16 in
Length Range
6 - 8 in
Thickness
4 - 6 inches
Thickened edge of slab on grade
Sonotube Footing
Width Range
8 - 10 in
Length Range
8 - 10 in
Thickness
48 - 60 inches
Circular pier for deck or support post
Important Considerations
- Frost depth varies by climate (check local codes)
- Soil bearing capacity affects footing size
- Expansive soils require special design
- Always consult local building codes
Calculate Materials for Your Project
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