What Is Basement Waterproofing?
Basement waterproofing is any system that keeps water out of a basement or carries it away before it causes damage. In Toronto the problem usually comes from three places: groundwater pushing against the foundation because the old weeping tile has failed, surface water from poor grading and downspouts, and sewer backups during heavy storms. Each needs a different fix, so we start by finding where the water is actually coming from.
Because we are an excavation and underpinning contractor first, exterior waterproofing is natural work for us. Digging down to a footing along a narrow side yard, protecting gas lines and supporting the wall while it is exposed is what we do every week.
Types of Waterproofing We Install
Exterior waterproofing
We excavate along the foundation down to the footing, clean the wall, repair cracks and parge it smooth, then apply an elastomeric waterproof membrane. A dimple drainage board, such as Delta-MS, goes over the membrane to protect it and give water a path down to the footing. New perforated weeping tile is laid in clear stone at the footing and connected to a sump or the storm system, then the trench is backfilled and graded away from the house.
Interior waterproofing
Where exterior digging is not practical, under a driveway, a deck or a side yard too narrow even for us, we cut a channel around the inside perimeter of the basement floor, install a drain pipe in stone, connect it to a sump basin and pump, and finish the floor. Water may still reach the wall, but it is caught and removed before it reaches the floor.
Sump pumps and backwater valves
A sump collects water from the weeping tile and pumps it out. A backwater valve stops city sewer backups from entering through floor drains. Both may qualify for the City of Toronto Basement Flooding Protection Subsidy.
Waterproofing during underpinning
When we underpin or dig out a basement, the footings are exposed anyway. Adding new weeping tile, a sump and a membrane tie-in at that stage costs a fraction of doing it separately later.
Reading the Signs
| What you see | Likely cause | Usual fix |
|---|---|---|
| Water at the floor-wall joint | Failed weeping tile, high water table | New weeping tile or interior perimeter drain |
| White powder on walls (efflorescence) | Water moving through masonry | Exterior membrane |
| Leaks at a crack | Cracked foundation wall | Crack repair plus membrane on that wall |
| Water after heavy storms at floor drain | Sewer backup | Backwater valve |
| Wet window wells | Poor drainage at the well | Well drain and grading |
| Damp but no visible water | Condensation or minor seepage | Grading, dehumidification, possibly membrane |
Toronto Conditions That Cause Leaks
Toronto has some of the most leak-prone basements in Ontario. Houses built before the 1960s often have clay weeping tile that has cracked or silted up after decades. South Etobicoke, the Beaches and other lakeshore neighbourhoods sit on sand with groundwater close to the surface, which our Etobicoke client saw every spring until we dug out, replaced the weeping tile and waterproofed the exterior. Many older homes had weeping tile connected to the sanitary sewer, which can push sewage back into the basement during storms.
The Rules and Permits
Excavating beside your foundation requires Ontario One Call locates, and gas meters and service lines often run right along the wall, so we daylight them first. Connecting a sump discharge or a severed weeping tile line has to follow the Toronto Sewer Use By-law, and backwater valves need a plumbing permit. If you plan to apply for the City subsidy, the work must meet the program’s conditions and you need the permit and invoices, which we provide.
Get a Straight Answer
Some waterproofing companies sell one system to every house. We would rather tell you what your house needs. Book a free site visit and we will find the source of the water, explain your options and send a written quote within 24 hours. If the leak started after a sewer or water line failure, see our sewer and watermain service.
