Should I waterproof or damp proof my foundation in New Brunswick?

In New Brunswick, full waterproofing is strongly preferred over damp proofing for any foundation that will be used as living space or finished basement — NB's high rainfall, spring snowmelt, and variable water tables make damp proofing alone insufficient for many sites. Understanding the difference between the two can save you from a very expensive mistake.

Damp proofing is the application of a spray-on or brush-on bituminous coating (asphalt emulsion) to the exterior of the foundation wall. It resists moisture vapour transmission and minor water contact, but it is not a true waterproofing membrane — it will not hold back water under hydrostatic pressure (standing water pressing against the wall). Damp proofing is what the minimum NB Building Code typically requires for below-grade walls, but minimum code compliance does not mean your basement will stay dry.

Full waterproofing involves a continuous, seamless membrane applied to the exterior of the wall — either a torch-applied modified bitumen membrane, a cold-applied rubberized asphalt membrane, or a spray-applied polyurethane system. When installed correctly with proper drainage board and weeping tile, a waterproofing membrane keeps water out even under sustained hydrostatic pressure.

Why NB conditions demand waterproofing for finished basements: New Brunswick receives 1,000-1,200 mm of precipitation annually. Spring snowmelt — especially the large snow loads that accumulate in Bathurst, Miramichi, and northern NB — saturates the soil rapidly and raises the water table. River valley communities like Fredericton and Miramichi face seasonal flooding conditions. Moncton, Dieppe, and Riverview are built on varied glacial soils that can hold significant moisture. The question is not whether water pressure will reach your foundation, but when.

The drainage tile system is equally critical. A waterproofing membrane without a functional weeping tile system is incomplete. Perforated pipe should be installed at footing level on a gravel bed, wrapped in filter fabric, and gravity-drained or directed to a sump pump. Without it, even the best membrane will eventually be overwhelmed by sustained hydrostatic pressure.

Cost difference: Damp proofing typically costs $1-$3 per square foot of wall area. Full exterior waterproofing runs $5-$10 per square foot installed, plus drainage board. For a typical NB home with 800 sq ft of below-grade wall area, that is a difference of roughly $2,500-$6,000 — modest compared to the cost of a wet basement remediation ($5,000-$15,000) or replacing finished basement materials after flooding.

If you are building new, waterproof properly from the start. If you are buying an older NB home in Moncton, Saint John, or elsewhere and discovering a wet basement, New Brunswick Concrete can match you with contractors who specialize in exterior and interior waterproofing solutions.