Exterior Basement Waterproofing in Ottawa — The Permanent Fix, Done Properly.
When water has to be stopped at the source. We dig it once, we do it right.
When exterior is truly necessary.
Exterior waterproofing is the most expensive and disruptive option in basement water management — and that's exactly why it gets oversold. A contractor with no incentive to be honest will quote it on jobs where interior would do.
But there are real situations where exterior is the only fix that actually works:
- The exterior waterproofing membrane has failed on a poured concrete wall
- A foundation crack needs to be repaired from outside (interior injection won't reach all the way through some walls)
- The exterior weeping tile has collapsed and needs to be replaced
- The wall itself needs repointing or structural restoration that requires exterior access
- The yard is being torn up anyway for a major landscaping or addition project (combine the work)
If you're in one of those situations, exterior is the right call and worth the disruption. If you're not, we'll tell you to do interior or do nothing.
The full exterior waterproofing process.
- Excavation — dig down along the foundation to the footing. This means removing landscaping, deck supports, walkways, or any structures in the dig zone.
- Wall inspection — once exposed, we look at the actual condition of the wall and any cracks needing repair before membrane goes on.
- Wall preparation — clean, repair cracks, repoint as needed, smooth surface for membrane bond.
- Membrane application — typically a rubberized asphalt or self-adhered membrane, sometimes with a dimple board exterior.
- Drainage gravel placed against the membrane to channel water down to the new weeping tile.
- Exterior weeping tile installed at footing level, wrapped in filter fabric.
- Backfill with clean material in lifts, compacted properly.
- Restoration of grading, landscaping, walkways — back to original or better.
Total time: typically 1-3 weeks depending on perimeter and complications.
Membrane systems we use and why.
Not all exterior membranes are equal. We typically work with:
- Self-adhered rubberized membrane — the modern standard, bonds directly to the wall, no torch or primer required for most applications. Long lifespan, proven performance in freeze-thaw climates.
- Dimple board — installed over the membrane in some applications, provides an air gap that allows any water that reaches the wall to drain freely.
We'll explain which we'd use on your job and why.
What happens to your yard.
Exterior waterproofing means the yard along the foundation gets dug up. Plan for:
- Landscaping removed and (where possible) replanted; some plants don't survive transplant
- Walkways, decks, patios, garden walls within the dig zone removed and rebuilt
- Heavy equipment access required — driveway and lawn ruts are common
- 1-3 weeks of active construction
What we do to minimize disruption:
- Document existing conditions with photos before we start
- Lay protection over lawn outside the dig zone
- Backfill, regrade, and reseed/sod as part of the project
- Replace landscape features that have to be removed (within scope)
We'll walk you through exactly what happens to your specific yard before any digging starts.
How long it takes and what it costs.
- Single wall exterior waterproofing: $8,000-$20,000.
- Full perimeter exterior waterproofing: $25,000-$60,000+.
- Add for new exterior weeping tile: $40-$80 per linear foot.
- Add for landscaping/walkway restoration: highly variable.
Variables that move the number: depth to footing, soil type, accessibility (can a small excavator get in?), what's in the dig zone, condition of the wall.
Full pricing context in our Ottawa foundation cost guide.
Lifetime expectations and warranties.
Done properly, exterior waterproofing should last 30+ years. The membrane systems we use carry manufacturer warranties of 20-25 years. Our workmanship warranty is 10 years and transfers with the property.
Other paths to a dry basement.
Exterior work is the permanent fix, but it isn't always the right one. Compare with interior waterproofing if exterior access is hard, or sump pumps and drainage if it's really a water-management problem. See the full picture on the waterproofing hub.