Water intrusion through beloved concrete foundations is typically the result of the following issues:
Foundation wall cracks, cold joints (where new concrete meets existing concrete ie in an addition of a home) improperly sealed snap ties and water, well, sewer and electrical conduit pipe penetrations. On rare occasions water can come through a concrete wall that has not been properly vibrated that creating a honeycomb area in the concrete.
Repairing Wall Cracks
The only way to repair foundation wall cracks would successfully be by the injection process. Injecting a typical wall crack with an epoxy or urethane resin is done under pressure pushing the material from the inside all the way to the outside. The injection process fills the crack from top to bottom, from inside to outside so repairing and stopping water intrusion. The old process of v-ing out a crack from the inside or outside and patching it with hydraulic cement or water plug will not work. Foundations are sooner to move and because the hydraulic cement or water plug does not have the strength to withstand future movement it will crack and cause the foundation wall crack to fail. Epoxy injections are considered structural repairs and will weld the foundation back together when done properly. Urethane injections will stop water but are not considered structural fixes. It is however flexible and can withstand movement in the foundation. Newer cracks on homes that have been allowed to settle for at least 1-2 yrs are good candidates for epoxy injection. Because epoxy is like superglue gluing or welding the foundation together it needs a fairly clean crack in order to be successful. For older homes that have had cracks previously repaired and have dirt and silt built up inside them, a urethane injection will be more successful in stopping water.
Repairing Cold Joints
Because no chemical bond is created when new concrete is poured against old concrete, cold joints, such as when you put an addition on your home, will often leak water. After the addition has been able to settle for a period of 1-2 yrs, the proper repair to stop water coming through a cold joint would be a urethane injection.
Repairing Snap Ties / Tie Rods
Metal snap ties / tie rods are used to hold the forms of a foundation in place while it is being poured. After the forms are removed, the snap ties on the outside are typically coated with a flexible polymer or hydraulic cement before a damp proof or water proofing membrane is applied to the foundation. These snap ties can leak over time if the prep work is not done properly. Injecting a snap tie under pressure from the inside with a urethane resin will stop leaking them from leaking.
Repairing Pipe Penetrations
During the construction of a home, holes in the foundations are cored to allow for water, well, sewer and electrical conduits to penetrate through the foundation. For example, a typical sewer line is 4 inches around. The hole cord may up to 5 inches or more so leaving a void between the outside of the sewer pipe and the concrete. Prior to backfilling the foundation on the outside, these voids are typically filled with hydraulic cement. Improper preparation around pipe penetration can cause water intrusion. To stop a pipe penetration from leaking, an injection of a urethane resin that expands up to 20x its volume thus filling the void from inside to outside should be used. Injecting around a pipe penetration from the inside will stop water seepage.
Repairing Honeycomb Areas
A honeycomb area in a foundation is the result of improper vibration or settling of the concrete thus leaving voids and pockets in the wall. Injecting a urethane resin under pressure will seal and fill these voids and pockets that stopping the leak.