Slide 16 of 19
- Why is the depth of foundation embedment important?
- Figure shows foundation embedment
- Footings must be deeply embedded so the foundation can resist vertical and horizontal loads
- Some homeowners have undermined the footings by grading on the lot – contractor should look for this problem
- Shear walls impart compression and sliding forces to the footing
- Deeper footings and better soil condition result in a better foundation to resist seismic loads
- Poor embedment allows the building to simply slide along the ground surface
- Measure foundation embedment as the depth into undisturbed soil
- Exclude the depth through loose top soils
- Rule of Thumb: The existing foundation depth should be no less than
12 inches for 1 story building,
18 inches for 2 story building, or
24 inches for 3-story buildings
- If not, or if there is evidence of expansive soils, consult an architect or engineer.
- If the foundation is not adequate, the house will slide and the retrofit work will be wasted