There are multiple different ways to tackle a foundation failure, depending on the problem and its severity, the method of repair changes.
As they say, different problem require a different solution, thus foundation repair processes for simple shrinkage cracks, vertical foundation movements and horizontal foundation movements are all unlike the other. A few foundation repair techniques and methods, commonly used, are explained below.
A crack or a fracture can be found in concrete or slabs on floor, they can be simple shrinkage ones not caused by structural movements that do not allow water, or there may be water entry-leaky cracks found in the foundation. A shrinkage crack may only be a tripping hazard and repaired fairly easily by chipping out the crack and applying a patching compound to the crack such as a sealant or epoxy or even a Polyurethane Foam injection. A crack in concrete slab or floor that allow entry of water may be caused by concrete settlement, or frost heaves can be covered and repaired by special poly urea caulks designed as joint filters, hydraulic cements poured on concrete or walls in a masonry way and then adding control joints in the concrete to further minimize the slab and concrete cracking.
Vertical Foundation Movements:
Vertical foundation movements may be due to expansive soils, severe earthquake damage or other seismic problems, settlement of footing and foundation and even frost heaves. They are mostly caused by downward or sinking movements of the foundation and may be repaired by slab jacking, using driven steel pins, helical piers or in extreme cases, a complete foundation reconstruction.
Slab Jacking: Also called mud-jacking, it is the process of lifting a building structure or driveway by pumping concrete or polyurethane resins beneath the object to be lifted. It’s a fast, relatively cheap and easy procedure that is usually performed when a foundation is so weak piers cannot be installed.
Driven Steel Pilings/Pins: This method involves insertion of a steel pin next to the foundation in the soil until it hits bedrock. It allows a more precise leveling of the foundation.
Helical Piers: In cases where driving a steel pin is unfeasible due to unfavorable soil conditions, shorter helical piers are used which are placed after digging a hole and then installing the screw-like pier.
Complete Foundation Reconstruction: If after inspection a failed foundation is deemed entirely unsalvageable, then an engineer will prescribe complete excavation and reconstruction. In some cases there may be a chance of reinforcing the original structure, but that is a rare possibility.
Horizontal Foundation Movements:
Horizontal shifts in building foundations are generally caused by external lateral forces. These forces include
- Soil and water pressure
- Impact pressures
- Frost pressures
- Seismic movements and pressures
These damages caused by these forces can show up as bulging or buckling walls, inward or outward leaning walls, wall shifting, step cracking or even a combination of leaning, bulging and creeping of foundation and wall components. To repair such problems the following possibilities may be considered:
- Building structural brick veneer walls
- Pinning the wall using steel pins to the surrounding soil of the foundation,
- Constructing a pilaster against existing foundation wall to add stability
- Use of foundation anchors
- Use of steel tension cables and reinforcing plates to allow the walls to resist further movements
- A full excavation and reconstruction of the entire foundation wall