Basement water issues are one of the most frustrating problems for homeowners in Toronto and across Southern Ontario. Whether it’s a persistent musty smell, visible cracks, or recurring flooding, waterproofing your basement is essential to protect your foundation, belongings, and indoor air quality.
In this pillar guide, you’ll learn everything you need to know about exterior basement waterproofing, the most effective long-term solution to moisture intrusion. We’ll walk you through the entire process, explain when permits are needed, share cost expectations, and help you compare alternatives like interior waterproofing, weeping tile systems, and foundation crack repair.
For more on related waterproofing topics, browse the full Aquamaster blog.
What Is Exterior Basement Waterproofing?
Before diving into the steps, it’s important to understand what exterior waterproofing actually involves. Unlike interior waterproofing systems that manage water after it enters your home, exterior waterproofing prevents water from reaching your foundation walls in the first place.
It involves excavating around the entire foundation, repairing damage, and creating a watertight barrier to block future leaks.
Compared to interior systems, exterior waterproofing:
Prevents structural decay
Stops mold growth at the source
Qualifies for permanent solutions under many warranty programs
If you’re deciding between waterproofing methods, our guide on internal vs. external waterproofing for basements outlines the pros and cons of each.
Step 1: Excavation Around the Foundation
The first step in exterior waterproofing is to excavate the soil surrounding the foundation walls.
This provides access to the full wall height and footing, which is critical for effective sealing and inspection. Excavation typically goes 6–8 feet deep, depending on your basement.
If you have landscaping, gardens, or walkways near the perimeter, they’ll need to be carefully removed and restored after the job is complete.
Excavation is also a key phase in projects involving basement underpinning and lowering if floor height.
Step 2: Wall Cleaning & Crack Inspection
Once the foundation walls are exposed, they must be thoroughly cleaned. This ensures that any waterproofing membrane will adhere properly.
Cleaning is followed by a visual and tactile inspection to detect vertical and horizontal cracks, mortar joint failure, or signs of mold and efflorescence.
Any damage found here will be addressed in the next step, often using methods from our foundation crack repair service.
Step 3: Foundation Crack Repair
All identified cracks and voids are sealed using hydraulic cement or polyurethane injection, depending on size and depth. This step is essential to prevent lateral water seepage through the foundation.
For structural cracks, additional reinforcement may be necessary. In such cases, our team provides structural foundation repair with engineer oversight.
Understanding the root causes of leaks is essential. Review our insights in The 5 Main Causes of Basement Leaks.
Step 4: Liquid Membrane Application
Next, a rubberized liquid membrane—commonly Aqua-Bloc—is trowel-applied over the entire wall. This membrane bridges over cracks and forms a seamless moisture barrier.
In homes with porous concrete or block foundations, the membrane may be reinforced with drainage fabric or mesh for durability.
This application forms the primary protective layer that keeps water from penetrating your foundation.
Step 5: Foundation Drainage Installation (Weeping Tile)
A perforated weeping tile system is installed at the base of the foundation to collect and redirect groundwater.
This drain pipe is wrapped in filter fabric to prevent clogging and is sloped toward a sump pit or storm drain, depending on your property layout.
For full installation info, see our weeping tile installation service or explore our article on what weeping tile is used for.
Step 6: Window Well & Drain (If Needed)
If your home has basement windows below grade, you’ll need to install window wells with proper vertical drainage.
Window wells prevent soil and debris from accumulating against the window. A vertical drain inside the well connects to the weeping tile system below to ensure proper drainage.
Learn more about how this works through our window well installation service.
Step 7: Backfilling & Soil Grading
Once all waterproofing layers and drains are installed, the trench is backfilled using clean soil. Proper compaction is critical to avoid future settlement.
The final soil grade should slope away from your home’s foundation by at least 6 inches over the first 10 feet to promote proper surface runoff.
For extra moisture control, consider damp proofing your foundation walls as a supplemental measure.
Step 8: Sump Pump & Discharge System
In areas with high groundwater or poor soil drainage, installing a sump pump system is highly recommended.
A sump pit collects water from the weeping tile, and the pump discharges it through a dedicated pipe away from the home.
Explore our sump pump installation and repair service or read about best practices for sump pump discharge lines.
Permits & Timelines
Most exterior waterproofing projects in Toronto and Ontario do not require permits unless structural changes are involved. However, always verify with your local municipality or contact us directly.
Typical timeline:
Small project (1–2 walls): 3–5 days
Full-perimeter waterproofing: 7–10 days
Permit timelines are also covered in our waterproofing & underpinning duration guide.
Cost of Basement Waterproofing in Toronto (2025)
The cost of waterproofing varies depending on wall length, depth, condition, and accessibility. On average:
| Service Type | Cost per Linear Foot | Typical Total Range |
|---|---|---|
| Exterior Waterproofing | $90–$160 | $8,000–$25,000 |
| Interior Waterproofing | $60–$100 | $4,000–$15,000 |
For a detailed breakdown, view our waterproofing cost guide.
FAQ: Basement Waterproofing in Ontario
Do I need to waterproof from the outside or inside?
Exterior waterproofing is best for permanent moisture prevention. Interior systems manage symptoms but don’t stop water from reaching your walls.
Can I stay in my home during waterproofing?
Yes, in most cases you can. Work is done outside. For underpinning projects or full renovations, temporary relocation may be needed.
How do I know if I need weeping tile?
If your basement floods frequently or the home is older, you likely don’t have weeping tile—or it may be failing. Weeping tile installation solves this.
Does waterproofing increase home value?
Yes. It improves structural integrity, air quality, and resale potential—especially in older homes across Toronto, Mississauga, and Vaughan.
Conclusion: Invest in Dry, Healthy Living Space
Exterior basement waterproofing is one of the best long-term investments for homeowners in the GTA. It prevents foundation damage, mold growth, musty smells, and chronic leaks—all while boosting property value.
Whether you’re dealing with visible cracks, standing water, or just want peace of mind, Aquamaster offers full-service waterproofing backed by long warranties and expert crews.
Ready to get started? Book your free estimate today and discover why thousands across Toronto, North York, Richmond Hill, and the rest of Ontario trust Aquamaster.
