Interior Basement Waterproofing in Markham
Interior basement waterproofing is the fastest, least invasive way to manage groundwater and floor-wall seepage in your Markham home. We install perimeter drainage tied to a high-output sump system — and we'll tell you honestly if exterior is what you actually need instead.
Signs you need interior basement waterproofing
- ✓Water seeping at the joint between basement floor and walls
- ✓Hydrostatic pressure pushing water up through floor cracks
- ✓Inaccessible exterior walls (neighbours, decks, additions)
- ✓Need for a fast, less invasive solution
Written Workmanship Warranty
Our work is backed for life — and the warranty stays with the home if you sell. That's a real selling feature when you list your Markham property.
Free, no-pressure inspection
A real local technician comes out, diagnoses the actual source, and gives you a written fixed-price quote. We'll tell you if you don't even need us yet.
Our process
Diagnose source
Confirm interior is the right approach.
Cut perimeter channel
Along the wall-floor joint, full length needed.
Install drainage + membrane
Tied to a new or upgraded sump pit.
Test and warranty
Workmanship warranty on workmanship.
Mold from a damp basement isn't just ugly — it's dangerous.
Hidden mold spores from a wet basement are linked to asthma attacks, chronic coughs, allergies and serious respiratory illness — especially in kids, seniors and anyone with a weak immune system. Every day you wait, it spreads further into your walls, insulation and air.
"They installed a perimeter drainage system and battery-backup sump pump in two days. Even during last summer's blackout, the backup kicked in and we never saw a drop. Worth every penny."
Frequently Asked Questions
What is interior basement waterproofing?+
Interior basement waterproofing means installing a perimeter drainage channel cut into the basement floor along the wall-floor joint, then tying it to a sump pit. Water that enters drops into the channel, flows by gravity to the pit, and is pumped out.
When is interior the right choice?+
Floor-wall joint seepage, hydrostatic groundwater pressure, or when exterior excavation isn't possible (against a neighbour's wall, under a deck or addition you can't disturb). It's also a great budget-conscious option for partial fixes.
Will interior waterproofing stop wall cracks from leaking?+
Not by itself. Wall crack leaks need crack injection or exterior membrane work. We'll tell you straight if interior alone won't solve your problem.
How disruptive is interior waterproofing?+
We cut along the perimeter of your basement floor, so there is some dust and noise for 1–3 days. We protect floors and contents, and clean up daily.
How much does interior basement waterproofing cost?+
Roughly $90–$130 per linear foot, plus $1,200–$2,000 for a new sump pit and pump if needed. A typical 30-ft wall: $2,700–$3,900 plus pit.
Wet basement? Don't wait.
Every day water sits in your basement, mold spreads and your foundation weakens. Talk to a real Markham waterproofing expert today — free advice, no pressure.