If you've got water finding its way into your basement, you've probably already run into the two competing answers: interior waterproofing or exterior waterproofing. Both are legitimate, both work - but they solve the problem in fundamentally different ways, and picking the wrong one for your situation means paying for a fix that doesn't actually match your entry point.
The Core Difference: Stopping Water vs. Managing Water
Exterior waterproofing stops water before it ever touches your foundation wall. Crews excavate down to the footing on the outside of the house, apply a rubber or crystalline membrane directly to the wall face, add a drainage board, and often install new weeping tile at the base - so groundwater is diverted away before it can build pressure against the concrete at all.
Interior waterproofing takes a different approach: it lets water reach the wall, then catches it before it reaches your floor. A drainage channel is cut into the concrete along the base of the interior foundation wall, collecting any water that seeps through and routing it to a sump pit, where a pump discharges it away from the house.
Interior Waterproofing - Lower Disruption, Lower Cost
Installable any season, no impact to landscaping, and the lower-cost option for most homes. The tradeoff: the foundation wall itself stays hidden behind the drainage channel.
Exterior Waterproofing - The More Comprehensive Fix
Stops water before it contacts the wall and lets crews inspect and repair the actual exterior wall condition while excavated. The tradeoff: full perimeter excavation disrupts landscaping and costs more.
Neither method is universally better - both work well when matched to the right conditions. We recommend based on your specific entry points and site access, not a default preference.
Why Hamilton Basements Are Especially Prone to This
Hamilton sits on clay-heavy soil across much of the city, and clay holds water against foundation walls long after rain has stopped falling - building up hydrostatic pressure that eventually finds the weakest point in the wall. Combine that with weeping tile that's failed or was never installed (common in homes built before 1980), and it's not surprising that most older Hamilton basements deal with water at some point.
What Each Method Costs in Hamilton
An interior drainage system typically runs $8,000 to $20,000 for a full perimeter system with sump pit and pump. Exterior waterproofing runs $15,000 to $40,000 depending on foundation depth and site access. If a single active crack is the only entry point, crack injection alone can resolve it for $500 to $2,000. BaseWorks diagnoses the actual entry points first, on a free assessment, before recommending either method - never a default sales pitch toward the pricier option. Full details are on our basement waterproofing service page.
Which One Is Right for Your House?
Interior waterproofing is usually the right call if:
Exterior waterproofing is usually the right call if:
Frequently Asked Questions
Yes - some homes with multiple active entry points benefit from both, particularly when a foundation crack needs exterior repair alongside an interior drainage system as a backup line of defence.
Both are built for 20 to 30 years of service when installed correctly. Exterior systems stop water at the source, while interior systems rely on the sump pump staying operational - which is why a battery backup is worth considering with an interior system.
Most straightforward waterproofing work doesn't require the same permitting as structural work like underpinning, but any project involving excavation near the foundation should still be assessed by a professional familiar with City of Hamilton requirements.