Question: Can you tell me why I have seepage in my basement walls at the base? I live in the West End in an older house. It happens only in the part of the basement that faces the back of the house.
There is no standing water, just seepage. We are having a garage built soon, so the grading that will be done might help.
What are the solutions to fix this problem and would it be a job a homeowner could do themselves? Thanks, Grace Livingston
Answer: Moisture in a basement is attributable to several factors, either due to poor water management outside the home or foundation related issues. The former are things that can be attended to by the homeowner, part of general maintenance, but the later is the job of an experienced foundation contractor.
Damp basements can take several different forms. Some have active water intrusion, normally during heavy rains or spring snow melts. Others, like yours, may have a musty smell and wet foundation walls with visible efflorescence or mould on the surface.
The first places I’d look are outside the home. The eavestrough system that takes rainwater of the roof must be in good condition and the downspouts extended well away from the foundation. If the troughs are loose, rusted, or have any visible leaks, they must be immediately repaired or if badly deteriorated, replaced. If they are loose and pulling away from the fascia, water can run behind and drain directly on to the soil outside the foundation walls. With heavy rainfall, or melting snow, this moisture can cause erosion of the soil or moisture buildup directly against the foundation.
If the troughs are in good condition and draining properly, ensure that you have downspout extensions of sufficient length to channel rainwater well away from the home. If the extensions are not adequate, the troughs leaking, or grading sloping improperly toward the house, moisture intrusion is much more likely. So, the next area to address is the grading around the house. This is the technical term for the slope of the soil adjacent to the foundation and in the rest of the yard surrounding your home. Ideally, there should be a soil slope of approximately 10 to 15 degrees, or more, for the first metre or two away from the foundation.
The third item to address is large trees near the house, or excessive vegetation up against the foundation and walls. The next possible cause of your dampness issues may be due to the age of your foundation and normal deterioration. In older homes like yours the weeping tiles that are installed underground, near the bottom of the foundation walls, stop working. These short clay or concrete tubes are designed to collect excess moisture from the soil and channel it under your foundation into the floor drain catch basin, and then harmlessly to the city sewer system. Over several decades, these fill up with soil, crack, crush, or shift, and become useless.
If the foundation develops small cracks, rusted form ties, or normal deterioration to the bitumen damp-proofing applied to the concrete during construction, the foundation can leak. In that situation, the only real solution is to excavate the soil outside the foundation, waterproof the concrete walls, install a new plastic weeping tile system, and replace the soil with better draining fill before regrading. That is not something most homeowners can safely or properly complete, so hiring an experienced foundation contractor will be warranted.