Wet Basement Markham
A wet basement Markham homeowners report may be a sump failure in a newer finished lower level or groundwater working into an older foundation in Unionville or Thornhill.
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What makes a Markham basement wet
Markham has a lot of houses built in the last few decades, with large finished lower levels, and a few older cores where the foundations are far older. Both types take on moisture, in different ways. Newer houses often depend on a sump pump and a clean window well. Older ones may have crumbling parging, original clay tile and no modern weeping tile.
The Rouge River and branches of the Don River run through Markham, and the ground slopes toward them. Houses near the valleys can see high groundwater in a wet spring.
Markham's plumbing protection program
The City of Markham operates a Private Plumbing Protection Rebate Program for eligible private plumbing work, such as backwater valves, weeping tile disconnection with a sump pump and lateral repair. Since the City has changed the program details over time, read the current rules on markham.ca before you begin. The City has also warned residents about scam calls related to the program, so call only contractors you have chosen yourself.
If your basement is already wet, deal with the water first. Prevention can follow once the space is dry.
What we look for in a Markham basement
- Efflorescence and staining at the base of walls
- Damp carpet edges and baseboards
- A sump pit that is dry, full or running constantly
- Window wells that hold water after rain
- Wet insulation behind finished walls
- Plumbing leaks behind vanities and laundry boxes
Working through the problem
- CallWe answer at any hour.
- AssessA free assessment with meters and a thermal camera, followed by a written scope and price.
- Strip and drySaturated materials come out, and drying equipment goes in.
- VerifyWe return to read moisture until it matches dry reference readings.
- RecordPhotos and readings are kept for your insurance adjuster.
Townhouses and newer subdivisions
A great many Markham homes are townhouses, where walls are shared and one wet unit can affect another. If the water came from your side, we dry your unit and give you records to show where it started. If it came from next door or from a shared line, we say so in the notes and flag it for the manager or board.
New subdivisions often have builder-finished basements with cold-air returns and floor-level vents, and water can enter ductwork. We check supply and return runs as part of the assessment when water has reached the floor.
Spring melt and summer storms in Markham
Markham's valleys carry meltwater in spring and storm water in summer. Look along foundation walls after either, check that sump discharge pipes run away from the house and make sure no downspout empties against the wall. If a lower level feels damp, tell us the date you first noticed it and any recent rain. That helps us trace the source and tells your insurance adjuster when the loss began.
Markham's downspout program and flood priority areas
The City of Markham says its Citywide Sanitary System Downspout Disconnection Program, an investigation and enforcement effort rather than a rebate, was completed on December 6, 2022 in the high-risk areas of Thornhill, Unionville and Markham Village. The City also names those areas, along with the Don Mills Channel, as flood control priorities. If a basement is wet in one of them, the City's page on basement flooding and sewer backup prevention is the place to check which measures it will pay toward (checked November 2026).
Markham wet basement questions
Why does my basement smell damp after a storm?
Wet drywall, carpet or insulation holds moisture. Locating and removing it is what clears the smell.
Can I wait to see if it dries on its own?
Waiting is risky. Materials that stay wet for several days can grow mould.
Do you handle townhouses?
Yes, and we coordinate with condominium or townhouse managers where needed.
Request a quote
Tell us what you need and we will get back to you. In a hurry? Calling is fastest.