Commercial Waterproofing for Buildings in Toronto & the GTA
Commercial waterproofing protects the below-grade parts of buildings that people live and work in: multi-unit residential buildings, retail and office properties, underground parking and storage, and industrial buildings. We stop leaks in foundations, walls and slabs and keep water out of spaces that cannot afford downtime.
We work with property managers, owners, condo boards, developers and general contractors. Every job starts with a site assessment and ends with a written scope, a photo record and a written warranty — so you have what you need for the board, the owner or the file.
For homes and residential basements, see our residential basement waterproofing services.
Buildings We Work On
Multi-unit residential
Low- and mid-rise apartments, townhouse complexes, basement units and lobbies below grade.
Retail & plazas
Storefronts with basements, strip plazas, restaurants and storage rooms.
Offices
Small office buildings, below-grade offices and mechanical rooms.
Parking & underground
Underground parking ramps, storage levels and below-grade service rooms.
Industrial & warehouse
Loading dock walls, pits, slabs and foundation walls of industrial buildings.
New construction
Foundation waterproofing packages for developers and GCs — see foundation waterproofing.
Positive-Side vs Negative-Side Waterproofing
On a commercial building the right side to work from often depends on access, occupancy and what is next to the wall.
| Positive side (outside) | Negative side (inside) | |
|---|---|---|
| Where | On the soil side of the wall | On the inside face of the wall or slab |
| How | Excavation, membrane, drainage board, footing drain | Crack injection, drainage channels, coatings, sump systems |
| Best for | Accessible walls, new construction, major leaks | Occupied buildings, walls under sidewalks, parking or neighbours |
| Disruption | Outside work area, landscaping or paving | Inside work area, often phased by unit or zone |
| Stops water | Before it reaches the concrete | After it reaches the concrete, before it enters the space |
Our Commercial Waterproofing Services
Below-grade leaks
Stopping active leaks in foundation walls and slabs.
- Foundation and slab crack injection
- Exterior membrane and drainage
- Interior drainage and sump systems
- Window wells and below-grade openings
- Pipe and conduit penetration sealing
Drainage & pumping
Moving water away from the building before it becomes a leak.
- Weeping tile and perimeter drains
- Sump pits and duplex pump setups
- Backwater valves and drain checks
- Area drains at ramps and stairwells
- Grading and surface drainage
Planned work
Scheduled projects with a clear scope and documentation.
- Waterproofing during renovations and repairs
- New construction foundation packages
- Phased work in occupied buildings
- Preventive inspections for property managers
- Written reports for boards and owners
Match the Problem to the System
| What you see | Likely cause | Typical system |
|---|---|---|
| Water through wall cracks in a parking or storage level | Cracks under water pressure | Injection, drainage behind the wall |
| Wet floor–wall joint in basement units | Groundwater, failed perimeter drain | Interior drainage + sump |
| Efflorescence and damp walls along a street side | Seepage, no exterior membrane | Negative-side system if excavation is not possible |
| Water at loading docks or ramps | Surface water and failed drains | Area drains, grading, joint sealing |
| Floor drain backups during storms | Sewer surcharge | Backwater valves, drain inspection |
| Leaks at pipe and conduit entries | Unsealed penetrations | Penetration sealing inside and out |
How We Run a Commercial Waterproofing Project
Site assessment
We walk the building with you, review drawings and leak history and document conditions.
Written scope
System, areas, schedule, access needs and warranty — in writing.
Planning
Access, tenant notices, parking closures and work hours agreed with management.
Phased installation
Work done zone by zone to keep the building operating.
Documentation
Photos of each stage, including work hidden after backfill or finishes.
Testing
Drains and pumps tested; areas checked after rain where possible.
Close-out
Clean site, final report and written warranty.
What Property Managers and GCs Get
Every project includes
- Site assessment and written scope
- Fixed quote for the agreed scope
- Photo record of the work
- Written warranty
- One contact person
We plan around
- Tenants and occupied units
- Parking and access restrictions
- Construction schedules and other trades
- Weather windows for exterior work
- Board and owner approvals
Commercial Waterproofing Cost
Commercial projects are quoted per project after a site assessment. Residential rates give a starting point; depth, access and occupancy change them.
| Work | Starting point |
|---|---|
| Site assessment & written scope | Free |
| Crack injection | From $500 per crack |
| Interior drainage | From $50 per linear foot |
| Exterior membrane & drainage | From $100 per linear foot |
| Sump and backwater valve systems | Quoted per project |
| Multi-area or phased projects | Quoted per project |
Starting points from our 2026 residential prices; commercial quotes reflect depth, access, phasing and site requirements.
Waterproofing Work by Our Crew
Real Leaquida job sites.
Related Services
Positive-Side vs Negative-Side Waterproofing
| Positive side (outside) | Negative side (inside) | |
|---|---|---|
| Where it goes | On the soil side of the wall | On the interior face or as interior drainage |
| Stops water | Before it enters the concrete | After it passes through, by collecting or blocking it |
| Access | Requires excavation or new construction | Works without digging; building can stay in use |
| Best for | New builds, underground parking, full retrofits | Occupied buildings, tight lots, shared walls |
Commercial Leak Symptoms and the Systems That Fix Them
| What you see | Usual system |
|---|---|
| Leaking cracks in a parking garage or foundation wall | Polyurethane or epoxy crack injection |
| Water at wall-floor joints in a below-grade space | Interior drainage with sump |
| Walls damp across large areas | Exterior membrane or interior crystalline/cementitious coating |
| Water rising through slabs | Under-slab drainage or pressure relief |
| Sewer backups into lower levels | Backwater valves on building drains |
Materials We Waterproof
Poured concrete
Foundation walls, parking decks and slabs.
Concrete block
Older commercial and multi-unit buildings.
Stone and brick foundations
Heritage and older mixed-use buildings.
Precast and ICF
Newer construction and additions.
Commercial Waterproofing Questions
What is commercial waterproofing?
Waterproofing the below-grade parts of commercial and multi-unit buildings — foundation walls, slabs, parking and storage levels — with membranes, drainage, crack injection and sump systems.
What types of buildings do you work on?
Multi-unit residential buildings, retail and plazas, small office buildings, underground parking and storage levels, industrial buildings and new construction foundations.
What is the difference between positive-side and negative-side waterproofing?
Positive-side systems go on the outside (soil side) of the wall and stop water before it reaches the concrete. Negative-side systems go on the inside and manage water that reaches the wall — useful when excavation is not possible.
Can you waterproof an occupied building?
Yes. We phase the work by zone, plan access and hours with management and keep areas clean and safe for tenants.
Do you work with general contractors on new construction?
Yes. We quote foundation waterproofing from drawings, work to the construction schedule and document the work before backfill.
How much does commercial waterproofing cost?
It is quoted per project after a site assessment. As a starting point, crack injection starts from $500 per crack, interior drainage from $50 and exterior membrane from $100 per linear foot.
Do you provide documentation?
Yes — a written scope, a photo record of the work and a written warranty at close-out.
What areas do you serve?
Toronto and the GTA, including Etobicoke, North York, Scarborough, Mississauga, Brampton, Vaughan, Markham, Richmond Hill, Oakville, Burlington and Milton, plus Barrie and Orillia.
What is the difference between positive-side and negative-side waterproofing?
Positive-side waterproofing is applied on the outside of the wall and stops water before it enters. Negative-side waterproofing works from inside, by blocking or collecting water that has passed through the wall.
Can commercial waterproofing be done without excavation?
Often, yes. Crack injection, interior drainage and interior coatings work from inside, which suits occupied buildings and tight urban lots.
Can a building stay open during commercial waterproofing?
In most cases. Work is phased by area and scheduled to limit disruption to tenants, customers and parking.
Request a Commercial Site Assessment
Tell us about the building and where water is getting in. We will assess the site and send a written scope and quote.
Call now — Mon–Fri 7 AM – 4 PM(416) 992-5858Office: 58 Six Point Rd, Etobicoke, ON M8Z 2X2
Email: info@leaquida.ca