We have been fighting our basement for 15 years. Two previous contractors did interior drainage (weeping tile systems), which helped but never fully solved it. Last fall we bit the bullet and did full exterior waterproofing. This is the detailed account.
The house: 1962 detached in Hamilton (Crown Point neighbourhood). Concrete block foundation, 1,100 sqft footprint. Average backfill depth to footing: about 7 feet.
What the inspection found: The parging on the exterior had failed in multiple locations — large sections were delaminating. The original drainage membrane (tar/bitumen) had completely cracked off. Several block courses had efflorescence and some spalling. The weeping tile from 1962 was collapsed clay tile — completely non-functional.
The work:
- Full excavation around all four sides to the footing (2.5 weeks, some hand-digging at tight spots near the addition)
- Power wash and wire brush all block courses
- Apply hydraulic cement to active cracks
- Two coats Bakor 790-11 waterproofing membrane
- Delta-MS drainage board over full height
- New 4-inch perforated weeping tile in gravel bed, filter sock, connected to sump system
- Clean gravel backfill to 18 inches from surface, native soil above
Cost: $24,200 all-in. The contractor (Hamilton-based, 22 years in business) offered a 15-year transferable warranty.
Result: Zero water. Not a single drop since completion including the wet November and snowmelt in March. The interior systems we installed before collected about 2-3 gallons per heavy rain event. Now nothing.
If your block foundation is actively leaking, interior drainage is a bandage. Exterior is the fix.