Basement Waterproofing Markham
Basement waterproofing Markham homes need is shaped by newer subdivisions with deep basements, heritage streets and the Rouge and Don river valleys.
All of our trades are licensed and insured
Mon to Fri: 8:00am to 6:00pm · Sat and Sun: Closed
Markham's different kinds of neighbourhood
Markham ranges from the heritage streets of Unionville and Markham Village to large subdivisions such as Cornell, Milliken and Berczy Village, and the edge of Thornhill. The Rouge River and Little Rouge Creek lie to the east, and the Don River's east branch runs through the west, so some lots sit close to a valley.
Heritage streets contain older homes on larger, treed lots, often with older foundations and drains. Newer subdivision homes are typically built close together on smaller lots with deep basements, sometimes with walkout or look-out windows. Their drainage depends heavily on the lot's engineered grading, which is a sloped surface designed to move water to a swale. When a deck, a shed, a patio or a landscaping project disturbs that slope, water can end up against the foundation.
Where waterproofing and grading meet
In newer Markham homes, the most common cause of a damp basement is not a failed wall but a change in grading, a downspout that discharges too close or a window well that fills with water. The first fix is often to restore the slope and extend the downspouts. If water continues to enter, interior drainage with a sump pit manages what reaches the floor, and exterior membranes are an option on lots with enough room to dig.
In older heritage homes, the stone or block foundation walls and clay tile drains require a different approach. Walls may be porous by design and benefit from drainage and ventilation rather than a hard coating that traps moisture inside the masonry. We examine the wall type before recommending a method.
Permits and programs in Markham
Permit requirements are set by each municipality. Before any work involving plumbing, structure or underpinning, confirm the requirement with the City of Markham building department, and ask whether any local flood-protection program applies to your property. The City of Toronto's basement flooding subsidy is limited to homes in Toronto and does not apply in Markham.
What we look at on a Markham property
- Engineered lot grading, swales and whether they are still working
- Decks, patios, sheds and fences that changed the water path
- Downspout outlets and window wells
- Foundation wall type: poured, block, stone or older masonry
- Sump pit and discharge, plus any battery backup
- Humidity in the finished basement and the ventilation serving it
How a Markham waterproofing plan comes together
- CallTell us about the house and where the water shows.
- Site reviewWe study the lot first, then the lower level.
- Written optionsGrading, interior drainage, exterior work or a combination, each explained.
- WorkInstalled with landscaping and finishes protected.
- Follow-throughWe test and show you how the system should behave in heavy rain.
Markham permits and the City's plumbing rebate
The City of Markham's guide to building permits says a housing permit covers finished basements, wall removal and interior alterations, while a project limited to plumbing needs a plumbing permit. A secondary suite requires a building permit and then registration with Markham Fire and Emergency Services, under the guide dated April 2026. The Building Permit Administration line is 905-475-4870.
The Private Plumbing Protection Rebate lists $1,750 for an indoor backwater valve, $2,000 for an outdoor one, $3,000 for a gravity weeping tile disconnection to the storm lateral and $5,000 for a weeping tile disconnection with a sump pump, with the City's extended deadlines of April 30, 2027 for the permit and July 31, 2027 for the application. These are the City's limits, not our fees (checked November 2026).
Frequently asked questions
Do new Markham homes need waterproofing?
Sometimes. Newer homes usually have drainage and a membrane, but changed grading or blocked drains can still cause leaks.
Is a hard coating right for an older stone foundation?
Often not. Older masonry may need to breathe, so drainage and ventilation are considered first.
Does the Toronto subsidy apply in Markham?
No. It is limited to Toronto properties.
Request a quote
Tell us what you need and we will get back to you. In a hurry? Calling is fastest.