If you’ve found water in the basement after this April’s rain, you’ve probably already pulled three quotes — and the spread between them is dramatic. One contractor is offering crack injection at $900. Another wants $22,000 for full exterior waterproofing. Both can be the right answer, depending on the foundation. Here’s how to tell which one your house actually needs.
The two repair categories, in plain language
Crack injection is an interior repair. A two-part polyurethane or epoxy resin is injected into the foundation crack from inside the basement, expanding to fill the full thickness of the wall. The work takes 2–4 hours per crack, leaves no excavation, and runs $650–$1,500 per crack in the GTA in 2026.
Exterior waterproofing is what it sounds like — excavate down to the footing along the affected wall, clean the foundation, apply a waterproof membrane, install (or replace) weeping tile, and backfill with drainage stone. It takes 3–7 days, requires landscaping restoration, and runs $15,000–$25,000+ for a typical bungalow side wall in 2026.
Same problem on paper, ten times the cost. The reason for the gap isn’t markup — it’s that the two repairs solve different problems.
When crack injection is the right call
Crack injection works when the foundation is structurally sound and water is entering through one or more discrete cracks in poured-concrete wall. Most poured-concrete foundations in the GTA built since the 1950s develop hairline cracks within a few years from concrete shrinkage; these are the textbook crack-injection candidates.
You’re a good candidate if:
- The foundation is poured concrete (not block, not stone, not brick)
- Water enters at specific points — usually a vertical line down the wall after heavy rain
- The exterior weeping tile is functional (the City’s storm sewer is taking water away)
- The crack is less than 1/8 inch wide and not actively shifting
In those conditions, the Government of Ontario’s building code resources treat crack injection as an accepted repair, and most reputable waterproofing companies will warranty the work for 10+ years.
When you actually need exterior waterproofing
Exterior waterproofing becomes the right answer when:
- The foundation is block, stone, or brick (injection doesn’t seal these reliably)
- Water enters along a broad area rather than at specific cracks
- The weeping tile is failing — collapsed, clogged with silt, or originally installed without a proper drainage stone bed
- You see white efflorescence patterns across the wall, not just a crack
- You’re already excavating for another reason (basement underpinning, walkout conversion, sewer replacement)
In these situations, injection treats the symptom but the water keeps finding new entry points. Six injections later, you’ve spent $5,000 and the basement is still wet — better to do the exterior job once.
What the City of Toronto will help pay for
Both repair types can qualify for funding through the City of Toronto’s Basement Flooding Protection Subsidy Program, which was expanded to up to $6,650 per property in late 2025. The relevant categories:
- Backwater valve installation — 80% up to $1,250
- Sump pump + battery backup — covered with the new battery-backup top-up
- Downspout disconnection — 80% up to $400
- Plumbing work to correct internal drainage issues — added in the recent expansion
The forum’s existing Toronto basement flooding subsidy thread walks through eligibility and the application form. The official City page is the Basement Flooding Protection Subsidy Program.
Note that the subsidy doesn’t directly fund crack injection or exterior membrane work — it funds flood prevention plumbing. Most homeowners with a wet basement need both: a waterproofing repair to stop water already entering, plus a backwater valve and sump system to prevent the next event.
Red flags when getting quotes
After 50+ years of seeing these jobs in the GTA, the same warning signs come up over and over:
- A contractor recommends exterior waterproofing without inspecting the inside first. Always start interior. If injection is going to work, you’ll know in one visit.
- A “lifetime warranty” with no company history. A 10-year warranty from a 30-year-old company is worth more than a lifetime warranty from a company that incorporated last quarter.
- No permit pulled for major exterior work. Excavating along the foundation often requires a building permit and almost always needs locates from Ontario One Call before digging.
- Quotes that include “we’ll figure out the price as we go.” A reputable waterproofing contractor inspects, photographs, and quotes a fixed scope. Time-and-materials on a basement job is how $5,000 quotes become $18,000 invoices.
- No mention of a sump pump discharge plan. A sump that pumps to the wrong place (foundation drain, neighbour’s lot line) creates a new flooding problem somewhere else.
Decision framework
If you have a poured-concrete foundation, one or two visible cracks, and water that only appears during heavy rain — start with crack injection. It’s the cheapest, fastest, and lowest-risk option. If it solves the problem, you’ve saved $20,000.
If you have a block or stone foundation, broad seepage, white mineral staining, or signs that the weeping tile is failing — plan for exterior waterproofing and apply for the City subsidy on the matching plumbing work in the same project.
If you don’t know which category your house falls into, post a few photos in this thread (foundation type, where the water is coming in, exterior grade) and the people in this community will give you a real read before you commit to any contractor’s quote.
For broader project planning context, the forum’s Most Commonly Asked Questions thread covers contractor vetting and contract terms — worth reading before signing anything.