Is The Foundation Crack A Structural Defect?
Nearly 100% of concrete foundations crack. This is because as the concrete cures, it shrinks in volume.This shrinkage causes stress on the concrete and to relieve that stress, it cracks. This is okay and the foundation is designed to handle the crack. The most common places on a foundation wall where this occurs at the corner of a window, where the wall "steps down" or in the middle of a long wall. These cracks are nearly vertical in nature and usually 1/2" or less. We recommend using a urethane foam for these cracks.
For a crack that is horizontal, runs at 45 degrees or less, or the wall has deflected, it can be assumed that the crack is structural and an epoxy should be used.The epoxy will restore the strength of the concrete wall. Please remember that cracks greater than 3/4" wide, horizontal or have deflection indicate that there is a stress on the foundation that must be remedied.Even though the epoxy will restore the concrete's strength, the stress may be more than any epoxy can withstand.Contact a foundation repair contractor who can install steel I-beams to completely restore the wall.
Low Pressure or High Pressure Injection for Concrete Cracks
Low pressure injection using surface mounted ports, single or dual cartridge resin cartridges and a hand trigger injection gun is the most common method to repair a crack. Professional waterproofing contractors know that this system works for 90% of cracks that they encounter.
Where to use low pressure
●Wider than hairline (wider than a fingernail or 1/32")
●Surface of the wall is dry (it can be damp, but not wet)
High pressure injection uses drill in place packers to get the resin into the crack. A grease gun filled with resin is attached to the packer. This process is used on actively leaking, hairline or cracks that have already been filled with hydraulic cement. Higher pressures are needed to get into a hairline crack than a trigger injection gun can generate. Also, water on the wall surface from actively leaking cracks will not allow the surface paste used with low pressure systems to adhere to the concrete.
Where to use high pressure
●Narrower than hairline (less than fingernail thick)
●Actively leaking water
●Previously repaired cracks