Basement Sealing Cost: Crack, Drain or Membrane?

Basement sealing typically costs $8,200 – $13,700 for a full system (typical $10,500), but one leaking crack can be fixed for a fraction of that: $890 typical. The right spend depends on how much water is coming in and where, so match the fix to the leak. All figures are before GST/HST.

Step 1: work out what kind of leak you have

Before you collect quotes, spend an hour with a torch and a dry spell after heavy rain. You are looking for one of three situations:

• One crack, damp or weeping. Water appears at a single vertical crack, usually after rain or thaw.
• Several cracks, or a damp line. Two or three cracks, or moisture where the wall meets the floor.
• A wet wall or floor. Water across a whole wall, standing water, or a sump that never gets a break.

The step you choose should be the cheapest one that actually stops that pattern. Paying for a full excavation to fix one crack is waste; injecting one crack when the whole wall is wet means paying twice.

Price steps, cheapest first

Situation	Fix	What we estimate
One crack	Crack injection (epoxy or polyurethane)	$700 – $1,150
Three cracks	Injection of each crack	See the cost guide, which has a "three cracks" option for the system you choose
Water along the wall base or floor	Interior drain and sump pump	$10,500
Wet wall, repeated failure, or structural concern	Exterior excavation and membrane	$21,100

The last two figures are typical mid-range costs for our default 30 m run of wall. Your price scales with the length of wall treated, so a short wall costs less and a full perimeter costs more.

Material	Typical	Usual range	Lifespan
Interior drain and sump pump	$10,500	$8,200 – $13,700	20-30 years
Exterior excavation and membrane	$21,100	$16,500 – $27,400	30-50 years

Crack injection: when it works

Injection suits a clean, stable crack in poured concrete. The installer seals the crack from the inside with resin, which fills it through the wall thickness. It is quick, usually done in a morning, and it is the cheapest route by a wide margin.

It works less well when:

• the crack keeps moving with the seasons, since resin can only follow so much;
• water is also coming through the joint at the floor, not just the crack;
• the wall is block rather than poured concrete, where water travels through the mortar joints.

Ask whether the repair is guaranteed against re-leaking and what the warranty says about movement. If a crack is wide, stepped or shows signs of the wall shifting, that is a structural question, not a sealing one. See our Foundation crack repair guide, and Foundation repair if the wall itself is moving.

Interior drain and sump pump: for water at the base

An interior system collects water at the footing and sends it to a sump pit, so it does not rely on keeping water out of the wall. It works from inside, so there is no digging up the garden, patio or driveway, and it usually costs noticeably less than going outside.

Points to check in a quote:

• Pump and backup. Ask what pump is included and whether there is a battery backup. A pump that fails in a power cut during a storm defeats the point.
• Floor reinstatement. Cutting a trench along the slab means breaking and re-pouring it. Confirm that is included.
• Discharge. Where the water goes matters. It needs to be sent well away from the foundation.

In Toronto, the City's Basement Flooding Protection Subsidy Program has covered parts of this work since 1 May 2026: up to $6,650 per property for eligible work completed on or after 12 Nov 2025, with each item at up to 80% of the invoice. That includes a sump pump up to $2,250 (one device) plus up to $300 for a battery backup, a backwater valve up to $1,600 per device (max two), severing and capping the storm sewer connection up to $400, and a home plumbing assessment up to $500. Contractors need a valid City of Toronto business licence, and a backwater valve needs a building permit and inspection. Outside Toronto, check what your own municipality offers.

Exterior excavation and membrane: when it is worth it

The exterior route digs down to the footing, cleans and repairs the wall, applies a membrane and installs drainage, then backfills. It deals with water before it reaches the wall, which makes it the most thorough option and the most disruptive.

It earns its cost when:

• the wall is wet along most of its length;
• interior fixes have failed before;
• the foundation needs repair at the same time, since the wall is exposed anyway.

Hidden costs sit on the surface. Decks, steps, planting, a walkway or a driveway beside the house may need to be lifted and rebuilt. Our estimate covers the waterproofing work, so ask each contractor what they will do about landscaping and hard surfaces, and budget separately for it. If a driveway is in the way, our New driveway guide shows what replacing it costs.

How we price this

We build each estimate from labour hours × local rates, plus materials, then check the result against market prices and real quotes. Excavation depth, access, soil and the length of wall are the largest drivers.

Before you sign

• Get the leak diagnosed first and ask each contractor to explain why their method suits what you have, not just what they sell.
• Compare at least three written quotes on the same scope: length of wall, pump spec, warranty, and restoration.
• Look at the gutters and grading. Water pooling next to the house is often the real cause, and downspouts that discharge at the foundation are an inexpensive fix. Our Gutter guards guide covers keeping gutters flowing.
• Check licences and permits. Plumbing work such as a backwater valve needs licensed trades and usually a permit.

Once you have quotes, run them through our "is my quote fair" tool to see how they compare with our live figures for your region. For the full breakdown, see the Basement waterproofing guide.