Concrete Foundation Walls - Structural Deterioration And Damage
Problem: Cracks in foundations and slabs resulting from settlement and movement.
Cause: Inadequate bearing.
Settlement and cracking are often caused by movement in the structure. When soil bearing is not adequate, problems are likely to occur.
Solutions: Ensure proper grade preparation. Always check with your local building department for your code requirements.
- Where the sub-grade is disturbed, provide granular fill, ensuring acceptable consolidation and compaction.
- Never pour concrete over frozen soils. In cold weather, pour as soon as possible after excavating, or provide frost protection. Keep concrete wet and warm for three days.
- Ensure proper compaction of granular fill over sewer lines running under footings. Ensure that service trenches are not located under foundation corners as shown in Figure 3.
Figure 3 - Settlement Over Underground Services
- A common problem area is found when step footings are used. A common building code requires that the vertical rise between stepped footings must not exceed 24 inches (600 mm) and the horizontal distance between risers shall be not less than 24 inches (600 mm) and provide generous filler to prevent shear failures at weak points in the footings as shown in Figure 4.