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Permanent injection repair for leaking basement walls from Thornhill to Cornell — plus the clearest guide anywhere to what Markham’s flood rebates actually pay for.
Coverage: Every Markham community, with crews dispatched from our North York base at 64 Millwick Dr — up the 404 corridor, working in York Region week in, week out. Assessments are free; most repairs finish in a single visit.
Foundation crack repair in Markham costs $750–$1,000 for polyurethane injection of a leaking crack and $850–$1,500 for structural epoxy — full-depth through metal ports, one visit, transferable lifetime warranty. Markham runs the GTA’s most generous basement-flooding rebate program (up to $5,000 per measure, extended to April 2027), but it funds valves, sump pumps and lateral repairs — not crack injection. We’ll tell you at the free assessment which side of that line your water problem is on.
Four building eras, four different calls.
| Community | Era | What we see at assessments |
|---|---|---|
| Thornhill (Markham side) · German Mills | 1960s–80s | Original pour cracks leaking as exterior damp-proofing reaches end of life |
| Unionville · Markham Village | Heritage cores + 1970s–90s streets | Older walls with decades of freeze-thaw; some heritage foundations need assessment before any method is chosen |
| Milliken · Armadale · Raymerville | 1970s–90s | Window-corner and form-tie cracks, frequently hidden behind finished basements |
| Berczy · Wismer · Cornell · Cathedraltown · Greensborough · Box Grove | 2000s–2010s+ | Shrinkage cracks in tall poured walls — the newest may still fall under the builder’s Tarion water-penetration coverage |
Era patterns, not a verdict on your house — the verdict happens at your wall, free.
Under all of it: York Region’s clay-rich till, which holds storm water against foundations for days after a big rain. That’s why the same crack that stayed dry for years starts weeping the spring after the damp-proofing gives out.
The most generous flood program in the GTA, quoted from the City’s own table.
| Measure (City pre-approval + permit required first) | Maximum rebate |
|---|---|
| Indoor backwater valve — sanitary or storm lateral | $1,750 |
| Outdoor backwater valve — sanitary or storm lateral | $2,000 |
| Weeping tile disconnection, redirected to storm by gravity | $3,000 |
| Weeping tile disconnection + sump pump installation | $5,000 |
| Lateral reline/repair — storm or sanitary | $2,500 |
Council has extended the Private Plumbing Protection Rebate Program to the end of April 2027, and every measure needs City pre-approval and permits before installation — install first and you can disqualify the rebate. Now the line: foundation crack injection is not on that table. A crack is a repair to your wall, not a flood-protection device, and no municipality rebates it. What the free assessment does is sort your water problem honestly — crack (injection, from $750, our side), sewer backup or weeping-tile infiltration (the City’s table, their process), or both at once. You leave knowing which is which before spending a dollar.
The method follows the moisture, never the other way around.
Metal ports on every injection, WSIB-insured crews, and a lifetime warranty that transfers with the house — worth having in a market like Markham’s where buyer inspections scrutinize basements. Pricing is the same published schedule as every city we serve: polyurethane $750–$1,000, epoxy $850–$1,500, tie-rod holes $75–$150, 5% off each additional crack. Get your number in the cost calculator or read the full crack injection guide.
Four questions, instant range — polyurethane or epoxy, multi-crack discount included, no obligation.
One visit for most walls, year-round.
Moisture, wall type, crack behaviour — and an honest call, including “this is a Tarion claim” or “this is a weeping-tile problem the City’s rebate actually covers.”
From the published schedule, on the spot, multi-crack discount applied. No expiry pressure.
One to two hours for most cracks — interior work, no excavation, finished basements opened and patched cleanly.
Lifetime, transferable, handed over before we leave.
Four factors, all visible at the assessment.
Finished basements are the big one in Markham — a large share of the housing stock has drywalled lower levels, so reaching the crack means opening and patching an access strip, priced up front. Wall height matters in the newer communities, where nine-foot pours mean longer cracks and more resin. Crack count works in your favour: every crack after the first is 5% off, and shrinkage cracks often travel in pairs. And heritage construction in the old cores can rule injection out entirely — stone and block foundations need a different approach, and we say so instead of forcing the method. The full driver breakdown lives in the cost guide.
The whole city, off the 404 and 407.
Thornhill, German Mills, Milliken, Armadale, Raymerville, Unionville, Markham Village, Berczy, Wismer, Cornell, Cathedraltown, Greensborough, Box Grove, Angus Glen — and everywhere between. More city guides: Vaughan · Brampton · Mississauga · Hamilton crack repair · all service areas.
What “full-depth injection” actually looks like on the wall, by our crews.
Backed by the DryShield family — a quarter-century of GTA basements kept dry.
Injection repairs warrantied for life — and the warranty moves with the house when you sell.
Full commercial coverage on every job, every crew, every home.
Eligible contractor for City of Toronto, Peel & Halton basement-flooding subsidy programs.
Inspection, honest diagnosis, and an exact per-crack quote — free, no pressure.
Your price is confirmed in writing before any work starts — no hourly surprises.
Flat published schedule, no Markham premium: polyurethane injection $750–$1,000 per leaking crack, structural epoxy $850–$1,500, tie-rod holes $75–$150, and every crack after the first is 5% off. Wall height and finished-basement access are what move a quote inside those ranges here. The number is confirmed at the free assessment, before any commitment.
No. The Private Plumbing Protection Rebate — extended to April 2027 — pays $1,750–$5,000 for backwater valves, weeping-tile disconnection, sump pumps, and lateral relining, all with City pre-approval and permits obtained before installation. Crack injection isn’t an eligible measure because it’s a wall repair, not a flood-protection device. If your basement problem spans both categories, the assessment separates them so you claim what’s claimable and repair what isn’t.
It’s the smart moment. Those projects usually mean the basement is already opened up, so any wall cracks are exposed and reachable — injection can be scheduled alongside without disturbing the City’s process, since it’s independent interior work with no permit involved. Sealing the walls while the floor project runs means the basement closes up dry on both fronts.
Older, not necessarily bigger. Heritage-core and mid-century walls have had decades of freeze-thaw working on the original pour, and their exterior damp-proofing is long past its service life — so cracks that were dormant for years begin to leak. Poured walls take injection normally; genuinely historic foundations of stone or block need an assessment first, because injection is a poured-concrete method and we’ll say plainly when it’s not the right tool.
Possibly your builder. Ontario’s Tarion warranty covers water penetration through basement or foundation walls for two years after closing and major structural defects for seven — so a young leaking crack may be a warranty claim rather than your invoice. We flag it at the assessment when the dates line up, and you keep the documentation either way.
No — hang up. The City of Markham has publicly warned that scammers pose as city employees to “inspect” or install sump pumps and backwater valves, and states it does not contact homeowners that way. Legitimate flood-protection work starts with you applying to the City, and legitimate crack repair starts with you calling a contractor. Nobody reputable begins in your kitchen uninvited.
Free assessment with straight answers — what’s a repair, what’s rebatable, what’s Tarion’s problem. Flat pricing and a transferable lifetime warranty.
