Project & Insights
Foundation Wall Waterproofing – Solutions for Condo Buildings
March 29, 2023
Concrete repair and waterproofing work at a high-end mid-rise condominium in the Bayview-Steeles area began in July 2021, and we have been contacted to do several projects since. The solutions provided included a new retaining wall to deviate water from the building and prevent leakage into the basement, concrete repairs in the parking garage (walls, columns, and ceilings), swimming pool waterproofing, and garage wall painting. Last week we were contacted to determine the sources of a leak into the basement and to waterproof the foundation.
Determining Leakage Source
To locate the source of the leak, the stones had to be removed and the existing waterproofing membrane exposed. It turned out that part of it was damaged, so it was removed as well, and the issue became evident – the leak originated around the tubes that come out of the foundation wall.
Foundation Waterproofing
The area was coated with a cold-applied polyurea-based waterproofing material, and geotextile was installed to provide a more durable result. It was coated with another layer of the waterproofing material, and an insulation board was installed to protect the new membrane. The stones were then placed back.
Learn more about a variety of concrete repairs and waterproofing solutions we can provide by visiting the different pages on our website.
Related: cold joint repair · polyurea membranes · pipe and cable penetration waterproofing · waterproofing for property managers · documented projects · common questions
Common questions
Frequently asked questions
Does the landscaping have to be dug up to fix a leaking wall penetration?
Often not. Many leaking conduit penetrations are sealed from inside the garage — wire-brushing the wall, parging the section housing the conduit and coating it with a cold-applied polyurea material — with no digging at all. Excavation earns its cost mainly where a previous repair has already failed, because the condition of a buried penetration cannot be judged without exposing it. On grass the reinstatement is straightforward: the existing spoil goes back, topped with topsoil and seed.
Why does excavation cost so much more than injection?
About 70 percent of a top-side repair is not waterproofing at all. It is excavating a wide area, hauling the material away, blasting off the old membrane, then restoring the sod, traffic topping, playground, or asphalt that was on top. Injection skips all of that by working from inside the garage.
Is negative-side injection as effective as digging up the deck?
In practice the success rates are comparable, and a consulting engineer on one GTA condo board conceded that a top-side dig is not 100 percent effective either — because nobody knows every place the membrane and joint have cracked. Injection also addresses the leak directly at its exit point rather than working across a broad excavated area.
When is digging up the deck the better option?
Top-side excavation makes sense when the deck membrane is failing broadly rather than at one or two joints, or when the landscaping above is being replaced anyway. If the excavation cost is already being spent for other reasons, redoing the membrane at the same time is sensible. For a localized joint leak, it rarely is.
What does white powder around a concrete crack mean?
White deposits around a concrete crack are calcium carried out of the concrete by water moving through it, and the amount tells you the volume of flow. A heavy white bloom means a sustained, significant water supply behind that crack — not an occasional seep. It is the strongest visual signal that a crack is an active water path rather than a cosmetic one.
Do you need to find where the water is entering before injecting?
No, and that is the main advantage of the method. The resin takes the path of least resistance, which is the same route the water used, so it travels back toward the entry point on its own. On garage decks this matters because water can travel 20 feet or more under a debonded membrane before it exits at the joint.
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