How Foundation Cracks Form
Poured concrete shrinks as it cures, and small cracks often appear within the first years after a house is built. Many stay dry. Others open slightly as the soil around the house freezes, thaws, wets and dries, and eventually water follows them inside.
Leaks often show up during spring thaw or after a long rain, when the soil against the wall is saturated. Look for a dark line that widens at the bottom of the wall, rust coloured staining, or a damp strip on the floor below a crack.
What Crack Injection Involves
Injection is a repair for poured concrete walls. Material is pumped into the crack under low pressure through ports set along its length. It travels through the wall to the outside face, filling the path that water was using.
Polyurethane and epoxy
Flexible polyurethane foams are commonly used for leaking cracks because they expand to fill voids and can tolerate slight seasonal movement. Epoxy is a rigid material that bonds the concrete on both sides and is used where structural bonding is the goal. The assessment determines which suits your crack.
When injection is not the right answer
Concrete block and stone foundations have hollow cores and mortar joints, so injection is rarely effective on them. Wide cracks, walls that bow or lean, and cracks with uneven sides can point to structural movement. In those cases we explain the findings and recommend the appropriate next step, which may include exterior foundation waterproofing or a structural review.
Step by Step: A Typical Injection Repair
- Clear the wall and remove any loose paint, parging or insulation over the crack.
- Clean the crack surface and set injection ports at regular intervals.
- Seal the face of the crack between the ports with a surface paste.
- Inject from the lowest port upward until material appears at the next port.
- Allow the material to cure, then trim the ports for a neat finish.
Most single crack repairs are completed in one visit, and the wall can usually be refinished once the material has cured.
Before You Finish a Basement
Cracks are far easier to repair while walls are open. If you plan to frame and drywall your basement, have every crack checked first. Hiding a slow leak behind insulation is one of the most common causes of hidden mould.
If you see water at more than one crack, or along the floor joint as well, a broader basement waterproofing plan may make more sense than repairing cracks one at a time.
Serving Brockville and Nearby Communities
We provide foundation crack injection in Brockville, Prescott, Gananoque, Athens, Lyn, Mallorytown, Maitland and the 1000 Islands area. See all service areas or browse the gallery for examples of this type of work.