How much does it cost to waterproof a basement in Toronto?

It depends almost entirely on which side of the wall the work happens. Interior drainage is published at $50 to $180 per linear foot across seven Ontario sources, so a 110-foot perimeter is roughly $5,500 to $19,800 before tax. Exterior excavation and membrane is published at $100 to $350 per foot by waterproofing companies and $250 to $650 per foot by excavation contractors pricing by depth, which puts the same perimeter anywhere from $11,000 to $71,500. Nusite Group puts a standard Toronto exterior job at $15,000 to $35,000 and DryShield at $5,000 to $20,000 and up.

Why is exterior waterproofing three or four times the price of interior?

Because you are paying for a hole, not for a membrane. Exterior work means excavating to the footing all the way round, hauling the spoil away, parging the wall, applying rubberized membrane and dimpled board, laying new weeping tile in clear stone, then backfilling and putting the yard back. OCM Excavation prices a single 30-foot wall on a Toronto semi at $8,500 to $13,500 all in. Interior work is a trench inside the footing, and none of the digging happens outside.

Does the basement depth really change the price that much?

Yes, and it is the number most quotes hinge on. OCM Excavation prices a standard 7-foot basement at $250 to $400 per linear foot, an 8-foot basement at $300 to $475, and a 9-foot or underpinned basement at $400 to $650. Every extra foot of depth is more spoil, more shoring and more time along the entire run, and below an underpinning bench the dig needs engineered shoring, which is why that top tier jumps rather than steps.

What does a narrow Toronto side yard add to the bill?

OCM Excavation adds $50 to $100 per linear foot to hand-dig where a mini-excavator will not fit, which is the situation on most old Toronto lots with a four-foot gap between houses. On a 30-foot wall that is $1,500 to $3,000 of pure access cost. Decks, air conditioning units and gas meters sitting in the dig line are taken off and reset for another $500 to $2,500.

Which method actually stops the water?

OCM Excavation's own answer is the useful one: exterior excavation stops water entering the wall, while an interior system manages water that has already got in. Both keep a basement dry to a homeowner standing in it. The difference shows up in the wall itself over freeze-thaw cycles, and in what happens when the foundation is not sound behind the finish. If the wall is in good shape, interior is the cheaper route to a dry floor.

Do these prices include HST, and is there any rebate?

The published rates are before tax, so add 13 per cent. On a $20,000 job that is $2,600. There is no City of Toronto subsidy for waterproofing itself, but the Basement Flooding Protection Subsidy Program does pay up to 80 per cent toward a sump pump, to a maximum of $2,250, and up to $1,600 per backwater valve, with a ceiling of $6,650 per property. If the job includes either, claim it.

What does basement waterproofing cost in Toronto?

Last updated: August 25, 2026By Below-Grade Records Desk

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Two numbers decide this bill: which side of the wall the work happens on, and how many feet of wall there are. Interior drainage is published across seven Ontario price lists at $50 to $180 a foot. Exterior excavation is $100 to $350 a foot from waterproofing companies and $250 to $650 from excavation contractors, who price it by how deep the basement is. Set both below.

Price your basement

Which system are you pricing?

Interior: basic drainageA trench cut inside the footing, new weeping tile, tied to a sump. It manages water that has already reached the wall.Interior: full perimeter with a drainage membraneThe same trench plus a dimpled membrane up the wall, so water running down the inside face is caught rather than soaking the floor edge.Interior: premium system with a backup pumpMembrane, full perimeter drainage and a second pump on a battery, so a power cut during the storm does not undo the whole system.Exterior: 7-foot basementOlder Toronto houses. Dig to the footing, parge, membrane, dimpled board, new weeping tile in clear stone.Exterior: 8-foot basementMost 1960s and newer bungalows. A foot more depth is a foot more spoil, shoring and time, across the whole run.Exterior: 9-foot or underpinned basementBelow an underpinning bench the dig needs engineered shoring, which is why this tier jumps rather than steps.

How many linear feet of wall?

The perimeter of a standard Toronto home is 100 to 120 linear feet (Nusite Group). One wall on a semi is usually about 30. Pace the outside of the house if you are not sure.

linear feet

Anything else in the job?

Add a sump pit and pumpNeeded when the weeping tile currently drains to the sanitary sewer, which Toronto's bylaw does not allow.

What this job costs in the GTA

$8,701–$18,645

with 13% HST. Before tax that is $7,700–$16,500.

Interior: full perimeter with a drainage membrane, 110 linear ft$70–$150 per linear footProject Landscaping; DryShield; Nusite Group: $7,700–$16,500
HST at 13%Government of Ontario: $1,001–$2,145

Second opinion, same job. RCC Waterproofing, DryShield, Nusite Group, Rock Basements, AquaMaster Plumbing publish interior work at a flat $50–$180 per linear foot with no depth tier, which on 110 linear ft is $5,500–$19,800 before tax. Where a quote lands between the two bands usually comes down to whether the company digs for a living or waterproofs for a living.

Published whole-project ranges. DryShield, Nusite Group put a complete interior job on a typical GTA home at $3,500–$18,000 before tax. An estimate far outside that is worth a second quote.

Per-foot rates are the published prices of the named Ontario companies, widened where they disagree and never averaged. What this cannot see: what is buried against the wall, how sound the foundation is once it is exposed, and how much finished basement has to come out to reach the floor edge.

Method

How is this estimate built?

WaterproofingIndex read seven Ontario waterproofing and excavation price lists in August 2026 and stored every per-foot range they publish, along with the sentence it was printed in. The calculator picks the rows that match the system you chose, takes the lowest low and the highest high across them, multiplies by your wall length and adds 13 per cent HST. Nothing is averaged.

Exterior work gets two answers rather than one, on purpose. OCM Excavation prices by basement depth and lands well above the waterproofing companies, who publish one flat band. Blending them would produce $100 to $650 a foot, which answers nothing. Both are shown side by side and each is named, because the gap between a digger's price and a waterproofer's price for the same wall is a real fact about this market and worth knowing before you read two quotes that differ by $20,000.

What the calculator cannot see: whether the foundation is sound once it is exposed, what is buried against the wall, how much finished basement has to come out to reach the floor edge, and whether the existing weeping tile is connected to something it should not be. Those are the four things that move a real quote inside the range.

Prices

What actually drives the price?

Depth.Seven feet to nine feet moves OCM Excavation's rate from $250 to $650 a foot. Depth multiplies across the entire run, so it is the single biggest lever in an exterior quote.
Access. A four-foot side yard means a shovel instead of a machine, at $50 to $100 more per foot. Semi-detached and row houses in old Toronto are where this bites hardest.
How many walls. Most leaks are on one wall. OCM Excavation prices one 30-foot wall at $8,500 to $13,500, against $25,000 to $55,000 to wrap all four. Doing the whole perimeter when one wall leaks is a choice, not a requirement.
Where the weeping tile currently drains. If it feeds the sanitary sewer, it is coming off, and a sump pit and pump at $2,500 to $4,500 goes in.
Putting the yard back. Interlock, patios and decks come out and go back. Landscaping restoration is frequently quoted separately, so check whether it is in the number you were given.

Frequently asked questions

How much does it cost to waterproof a basement in Toronto?: It depends almost entirely on which side of the wall the work happens. Interior drainage is published at $50 to $180 per linear foot across seven Ontario sources, so a 110-foot perimeter is roughly $5,500 to $19,800 before tax. Exterior excavation and membrane is published at $100 to $350 per foot by waterproofing companies and $250 to $650 per foot by excavation contractors pricing by depth, which puts the same perimeter anywhere from $11,000 to $71,500. Nusite Group puts a standard Toronto exterior job at $15,000 to $35,000 and DryShield at $5,000 to $20,000 and up.
Why is exterior waterproofing three or four times the price of interior?: Because you are paying for a hole, not for a membrane. Exterior work means excavating to the footing all the way round, hauling the spoil away, parging the wall, applying rubberized membrane and dimpled board, laying new weeping tile in clear stone, then backfilling and putting the yard back. OCM Excavation prices a single 30-foot wall on a Toronto semi at $8,500 to $13,500 all in. Interior work is a trench inside the footing, and none of the digging happens outside.
Does the basement depth really change the price that much?: Yes, and it is the number most quotes hinge on. OCM Excavation prices a standard 7-foot basement at $250 to $400 per linear foot, an 8-foot basement at $300 to $475, and a 9-foot or underpinned basement at $400 to $650. Every extra foot of depth is more spoil, more shoring and more time along the entire run, and below an underpinning bench the dig needs engineered shoring, which is why that top tier jumps rather than steps.
What does a narrow Toronto side yard add to the bill?: OCM Excavation adds $50 to $100 per linear foot to hand-dig where a mini-excavator will not fit, which is the situation on most old Toronto lots with a four-foot gap between houses. On a 30-foot wall that is $1,500 to $3,000 of pure access cost. Decks, air conditioning units and gas meters sitting in the dig line are taken off and reset for another $500 to $2,500.
Which method actually stops the water?: OCM Excavation's own answer is the useful one: exterior excavation stops water entering the wall, while an interior system manages water that has already got in. Both keep a basement dry to a homeowner standing in it. The difference shows up in the wall itself over freeze-thaw cycles, and in what happens when the foundation is not sound behind the finish. If the wall is in good shape, interior is the cheaper route to a dry floor.
Do these prices include HST, and is there any rebate?: The published rates are before tax, so add 13 per cent. On a $20,000 job that is $2,600. There is no City of Toronto subsidy for waterproofing itself, but the Basement Flooding Protection Subsidy Program does pay up to 80 per cent toward a sump pump, to a maximum of $2,250, and up to $1,600 per backwater valve, with a ceiling of $6,650 per property. If the job includes either, claim it.

Sources

Where these numbers came from

Seven Ontario price lists plus the provincial tax rate, each read on its own page in August 2026 and stored with the sentence carrying the figure. Canadian dollars, before HST unless a line says otherwise.

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