Leaking Crack Injection & Sealing · Waterloo
Leaking Foundation Crack Injection and Sealing in Waterloo
Most leaking cracks in Waterloo are shrinkage cracks in poured concrete from the 1970s onward. They are annoying, they are common, and they are one of the easier things in this trade to fix properly.
A poured concrete foundation shrinks a little as it cures, and it cracks where it shrinks: at the corners of basement windows, at steps in the wall height, near the corners of the house, and wherever a pipe or a beam pocket interrupts the wall. Beechwood, Lakeshore, Lincoln Village, Columbia Forest and most of Waterloo built after about 1970 has poured foundations, and most of those foundations have at least one of these cracks. Many never leak. The ones that do usually start twenty or thirty years in, when the tar-based dampproofing on the outside has aged and the clay backfill has settled away from the wall and left a path for water.
First, is it a leak or a movement?
Before any crack is injected, someone has to answer one question: is this crack only leaking, or is it moving? A shrinkage crack is typically narrow, roughly vertical or slightly diagonal, the same width along its length or tapering, and the wall on both sides of it is in the same plane. That is a waterproofing job. A crack that is wider at the top than the bottom, that steps, that runs horizontally, or where one side of the wall sits proud of the other, is a sign the foundation is moving. Injecting that crack seals a leak in a wall that is still going somewhere, and the crack reopens beside the repair. Movement is a structural foundation question and a different trade. If that is what we see, we say so and stop.
How injection works
- Expose the crack. If the basement is finished, a section of drywall comes off so the full length of the crack is visible from the floor to the top of the wall.
- Set the ports. Injection ports are fixed along the crack at intervals, and the surface of the crack is sealed between them with a fast-setting paste so the injected material cannot simply run back out.
- Inject. Polyurethane resin is pumped in from the lowest port up. It travels through the crack to the outside face of the wall, reacts with the water present and expands to fill the void. Epoxy is used instead where the crack is dry and the wall needs to be bonded back into one piece rather than simply sealed; that choice is made on site.
- Confirm. When resin appears at the next port up, that section is full. The process repeats to the top of the wall.
- Finish. Ports are removed and the surface is dressed. The repair is through the full thickness of the concrete, not a patch on the inside face.
A single crack is usually a few hours of work. Several cracks in one basement are done in the same visit.
What injection does not fix
Injection is for poured concrete. It does not work on concrete block, because the water is travelling through the hollow cores and the mortar joints, not one defined crack, and it does not work on the stone and brick foundations around uptown Waterloo and Mary-Allen for the same reason. Those walls need drainage. Injection also does not fix water coming in at the cove joint where the floor meets the wall, which is a water table problem and points to an interior weeping tile system. And it does not fix the reason the crack started leaking. If a downspout is dumping at that corner or the grade slopes toward the house, that gets corrected in the same scope or the next crack over starts weeping instead.
Cracks at windows and pipe penetrations
Two special cases come up in Waterloo houses all the time. The first is the crack that runs down from a basement window corner, often paired with a window well that fills with water because it has no drain or the drain is silted up. Injecting the crack without dealing with the well is half a job. The second is water around a pipe or conduit passing through the wall, common on the utility side of 1980s and 90s houses. That is sealed with the same materials, but the approach is different because there is no crack to inject; the void around the pipe is filled from inside and, where accessible, from outside.
Finished basements and student rentals
A lot of leaking cracks in Waterloo are behind drywall in finished basements, or behind the panelling in a student rental near the universities. The crack has usually been leaking longer than anyone knew. When the wall is opened, the framing, insulation and drywall that got wet are checked, and you get a straight answer about what should come out before the wall is closed again. For landlords, the repair is scheduled around tenants and documented in writing so there is a record for the next time the question comes up.
When we recommend something else
If there are many cracks in one wall, if the wall is block or stone, if water is coming in at the floor, or if the outside of the wall is accessible and the coating has clearly failed across a whole face, injection is the wrong tool and we will quote the right one instead. Sealing one crack in a wall that is leaking everywhere is a way to sell you the same visit twice.
Frequently asked questions
Can a leaking foundation crack be sealed from inside?
In a poured concrete wall, yes. Injection ports are set along the crack, the surface is sealed, and polyurethane or epoxy is pumped through the full depth of the wall to the outside face. It takes a few hours per crack and needs no digging. It does not work on block, stone or brick foundations, where water travels through joints rather than one crack.
Will the crack come back?
A properly injected shrinkage crack in a poured wall is sealed through its full thickness and does not normally reopen. If the crack is caused by ongoing movement of the foundation, it will reopen beside the repair, which is why every crack is checked for movement first and referred to a structural foundation contractor if it is moving.
Do I need to open my finished basement wall?
A section of drywall or panelling has to come off so the whole crack is visible from floor to top of wall. It is a small opening, and the wet insulation and drywall behind it are usually the reason you want it open anyway. You get a plain answer about what should be replaced before the wall is closed.
Serving Waterloo and surrounding areas. Contact us for a no-obligation quote specific to your property.