External Basement Waterproofing — Stopping Water From the Outside
Exterior basement waterproofing (also called external or outside waterproofing) stops water before it ever reaches your foundation wall. We excavate along the outside of the house down to the footing, clean and repair the wall, apply a waterproofing membrane, cover it with a dimple drainage board and install new weeping tile in clear stone. Then we backfill and slope the ground away from the house.
Because the wall is sealed on the side where the water is, waterproofing a basement from outside is the most complete fix for walls that leak in many places, old foundations with failed clay weeping tile, and basements you plan to finish. Nothing inside the basement has to be opened.
Looking for exterior waterproofing near me? Our own crews do below grade waterproofing across Toronto and the GTA, from our office in Etobicoke.
How Waterproofing a Basement From Outside Works
Each layer has its own job: the membrane keeps water out of the concrete, the dimple board relieves pressure and protects the membrane, and the weeping tile carries the water away.
Three Parts of an External Waterproofing System
A wall can be perfectly sealed and still get wet if the drainage or the grading is wrong. We deal with all three together.
Outside Foundation Wall
Waterproofing basement walls from outside puts the barrier where the water is — on the soil side of the wall.
- Excavation down to the footing
- Wall cleaned and inspected up close
- Cracks and holes sealed with hydraulic cement
- Parging repaired on block and stone walls
- Rubberized waterproofing membrane applied
Footing Drainage
Weeping tile at the footing collects groundwater and relieves the hydrostatic pressure on the wall.
- New perforated weeping tile with filter sock
- Bedded and covered in clear stone
- Filter fabric keeps soil out of the stone
- Drains to a sump pit or approved outlet
- Old clay tile replaced, not patched
Backfill & Surface
The last layer is the surface: water that runs off the roof and lawn should move away from the wall, not toward it.
- Dimple board protects the membrane during backfill
- Clean, compacted backfill
- Ground re-graded to slope away from the house
- Downspouts directed away from the foundation
- Window wells tied into the drainage
Our Exterior Waterproofing Process, Step by Step
Real photos from our job sites follow each stage of the work.
Free inspection
We check the walls inside and out, the grading, downspouts and the old drainage, and measure the linear footage.
Written quote
Scope, price, schedule and warranty terms in writing. Restoration of patios or walkways is listed separately.
Locates & protection
Underground utilities are located through Ontario One Call before any digging; lawns and gardens are protected.
Excavation
We dig along the wall down to the footing — machine where it fits, by hand in tight side yards.
Clean & repair
The wall is cleaned, cracks and holes are sealed and damaged parging is repaired.
Membrane & dimple board
A rubberized membrane goes on the wall, then the dimple board for drainage and protection.
Weeping tile & stone
New weeping tile in clear stone with filter fabric is laid at the footing and connected to the outlet.
Backfill & clean-up
We backfill, grade the soil away from the house, test the drainage and clean up.
Exterior Waterproofing Work, Stage by Stage
Real Leaquida projects in Toronto and the GTA — no stock photos.
How Much Does Exterior Basement Waterproofing Cost in Toronto?
Exterior waterproofing is priced by the linear foot of wall. Depth, access and what is in the way of the excavation make the biggest difference.
| Service | Typical price range | Typical duration* |
|---|---|---|
| Exterior waterproofing (excavation, membrane, dimple board, weeping tile, backfill) | $100 – $250 per linear foot | — |
| One wall (about 30–40 ft) | $3,000 – $10,000 | 1 – 3 days |
| Full exterior waterproofing project | $10,000 – $35,000 | 3 – 7 days |
| Foundation crack repair (added to the job) | $500 – $1,500 per crack | Same visit |
| Window well replacement | $1,000 – $5,000 per well | Same visit |
| Sump pump installation (new pit) | $1,500 – $3,900 | Usually 1 day |
| Inspection & written quote | Free | One visit |
*Typical for an average Toronto home; your schedule is written into the quote. Approximate 2026 price ranges, not a quote. Removing and rebuilding decks, interlock, concrete walkways or stairs is quoted separately. See the full basement waterproofing cost guide and calculator.
Depth of the foundation
Most Toronto basements need digging about 6–8 ft down to the footing; deeper walls take more time and shoring.
Access around the house
Tight side yards between older homes often mean digging by hand instead of with a machine.
What is in the way
Decks, stairs, interlock, driveways, AC units and mature trees along the wall add work.
Condition of the wall
Stone, block or heavily cracked walls need more repair and parging before the membrane.
Drainage outlet
If the old weeping tile runs to the city sewer, a sump pit may be needed for the new drain.
Length of wall
The more linear feet, the lower the cost per foot usually is.
Waterproofing Tar vs a Real Exterior Membrane
Many older Toronto homes were built with a thin coat of black tar on the outside of the foundation. That is damp-proofing — it slows moisture down, but it is not designed to hold back water under pressure.
| Tar / damp-proofing coat | Exterior waterproofing system | |
|---|---|---|
| What it is | Thin asphalt (tar) coating sprayed or brushed on | Thick rubberized membrane + dimple board + new weeping tile |
| Handles water under pressure | No — meant for damp soil only | Yes — made for hydrostatic pressure |
| Bridges small cracks | No, it cracks with the wall | Flexible membrane bridges hairline cracks |
| Drainage | None on its own | Dimple board and weeping tile carry water away |
| Typical in | Many older homes, original construction | Proper repair of a leaking basement |
The Ontario Building Code separates damp-proofing from waterproofing: where water pressure can build up against a foundation, waterproofing is required, not just a damp-proofing coat. If your basement leaks, re-tarring the wall usually does not fix it.
What Goes Into Below Grade Waterproofing
| Layer | What it does | Why it matters |
|---|---|---|
| Hydraulic cement | Seals cracks, tie-rod holes and voids | Gives the membrane a solid, continuous surface |
| Rubberized waterproofing membrane | Seamless barrier on the outside of the wall | Keeps water out of the concrete itself |
| Dimple board (drainage membrane) | Air gap and drainage path over the membrane | Relieves water pressure and protects the membrane from backfill |
| Perforated weeping tile with sock | Collects water at the footing | Removes the water that causes pressure on the wall |
| Clear stone | Surrounds the weeping tile | Lets water reach the pipe quickly |
| Filter fabric | Wraps the stone | Keeps soil and silt from clogging the drain |
| Clean backfill & grading | Restores the yard | Sends surface water away from the house |
Exterior or Interior Waterproofing — Which One Do You Need?
Both stop basement leaks; they do it from opposite sides of the wall.
| Exterior waterproofing | Interior waterproofing | |
|---|---|---|
| Where the work happens | Outside, excavating down to the footing | Inside the basement, along the walls |
| How it stops water | Seals the wall so water never reaches it | Collects water that reaches the wall and pumps it out |
| Yard, driveway, deck | Dug up along the wall, then restored | Not disturbed |
| Inside the basement | Not touched — finishes stay in place | Floor opened along the walls |
| Best for | Walls leaking in many places, failed outside weeping tile, finished basements | Floor–wall joint leaks, high water table, tight lots |
| Typical cost in Toronto | $100 – $250 per linear foot | $50 – $120 per linear foot |
| Works in winter | Depends on frost and ground conditions | Yes |
Exterior is usually the better choice when…
- Water comes through the wall itself, not just at the floor
- The basement is finished and you do not want it opened
- The outside of the wall is reachable
- The foundation wall needs repair or parging from outside
- The old clay weeping tile has failed
Interior may be better when…
- A driveway, deck or neighbour’s house is right against the wall
- Water rises at the floor–wall joint or through the floor
- You want to avoid excavation
See interior basement waterproofing — some homes get exterior on open walls and interior where digging is not possible.
Signs Your Basement Needs Exterior Waterproofing
Water through the walls
Damp patches or drips in the middle of the wall after rain or snowmelt.
White efflorescence
Powdery white deposits show water is moving through the concrete.
Leaking wall cracks
Cracks that seep in heavy rain — foundation crack repair may be needed too.
Crumbling parging
Loose or missing parging on the outside of block or stone foundations.
Failed weeping tile
Old clay tile that has collapsed, shifted or filled with roots and silt.
Wet behind finishes
Musty smell, stained drywall or mould behind finished basement walls.
Real Leaquida job siteWhy Outside Wall Waterproofing Matters in Toronto
- Much of Toronto sits on clay-rich soil that drains slowly and holds water against foundation walls.
- Footings here sit below the frost line, so most excavations go about 6–8 ft down.
- Many pre-1960s homes still have original clay weeping tile and a thin tar coating — both near the end of their life.
- Toronto encourages disconnecting foundation drains from the sewer; severing and capping the old connection can qualify for up to $400 from the City.
- Exterior waterproofing itself is not covered by the City subsidy, but a sump pump (up to $2,250) and backwater valve (up to $1,600 each) done with it can be.
Often Done Together With Exterior Waterproofing
Exterior Waterproofing in Toronto & the GTA
Same inspection, same written quote and same warranty wherever you live.
Exterior Waterproofing Questions, Answered
What is exterior basement waterproofing?
Exterior (external) basement waterproofing seals the foundation from the outside. The wall is excavated to the footing, repaired, coated with a waterproofing membrane and covered with a dimple drainage board, and new weeping tile is installed in clear stone before backfilling.
How much does exterior waterproofing cost in Toronto?
Exterior waterproofing usually costs $100–$250 per linear foot. One wall is often $3,000–$10,000 and a full exterior project $10,000–$35,000, depending on depth, access and what has to be removed. The inspection and written quote are free.
Is it better to waterproof a basement from the outside or inside?
Exterior waterproofing is best when water comes through the walls and the outside is reachable, or when the basement is finished. Interior waterproofing is best for floor–wall joint leaks, high water tables and walls you cannot dig along. After a free inspection we recommend the right one.
How long does exterior waterproofing take?
One wall usually takes 1–3 days and a full exterior project about 3–7 days, depending on wall length, depth, access and weather. The schedule is written into your quote.
How deep do you dig for exterior waterproofing?
We excavate down to the footing so the membrane and weeping tile cover the whole wall. In most Toronto homes that is about 6–8 ft below the ground.
What is dimple board waterproofing?
Dimple board is a plastic drainage membrane with raised dimples. Installed over the waterproofing membrane, it creates an air gap so water drains down to the weeping tile instead of pressing on the wall, and it protects the membrane from stones in the backfill.
Is waterproofing tar enough?
No. A tar coat is damp-proofing: it slows moisture but cannot hold back water under pressure and cracks with the wall. A leaking basement needs a real waterproofing membrane with drainage.
Can you waterproof just one outside wall?
Yes. If only one wall leaks we can excavate and waterproof that wall alone. We tie the new drainage into the existing system or a sump pit.
Will my landscaping be damaged?
The soil along the wall has to be dug up. We protect lawns and plantings where possible and restore the grade afterwards. Decks, interlock or walkways in the dig path are removed and rebuilt, and that part is quoted separately.
Can exterior waterproofing be done in winter?
Exterior work depends on frost and ground conditions, so we schedule it for when the ground can be dug safely. Interior waterproofing, crack injection and sump pumps can be done year-round.
Is exterior waterproofing covered by the Toronto subsidy?
The waterproofing itself is not. Work done with it can be: a sump pump (up to $2,250), battery backup (up to $300), backwater valves (up to $1,600 each) and weeping tile severance and capping (up to $400), at 80% of the invoice.
Do you offer a warranty?
Yes. Every exterior waterproofing job comes with a written warranty on materials and workmanship. The terms are written into your contract.
Get Your Exterior Waterproofing Quote
Tell us where the water shows up. We will inspect the walls inside and out, measure the work and give you a written quote for waterproofing your basement from the outside — no pressure, no obligation.
Call now — Mon–Fri 7 AM – 4 PM(416) 992-5858Office: 58 Six Point Rd, Etobicoke, ON M8Z 2X2
Email: info@leaquida.ca