Why Moncton Is Especially Vulnerable to Ice Dams
Moncton receives 200–300+ cm of snow annually and experiences frequent temperature swings — sometimes 20°C+ in a single day between November and April. This freeze-thaw pattern is the engine of ice dam formation. Heat escaping through an under-insulated attic warms the roof deck, melting snow from below. That water flows toward the eaves — which are cold because they extend beyond the heated living space — and refreezes into a ridge of ice.
With each subsequent snowfall and melt cycle, the ice dam grows. Eventually, pooled water behind the dam seeps under shingles through nail holes, seams, and any point where ice & water shield is missing or compromised. In Moncton homes built before 2000, inadequate attic insulation and missing vapour barriers are the most common root cause.
Step 1 — Upgrade Attic Insulation to R-50
The National Building Code of Canada 2020 recommends minimum R-50 attic insulation for NB's climate zone. Most Moncton homes built before 1990 have R-20 to R-30 — significantly below the threshold needed to keep the roof deck cold in winter.
Adding blown-in cellulose or spray foam to bring your attic to R-50 is the single most effective ice dam prevention measure. It stops the heat transfer before it ever reaches the roof deck. A typical Moncton bungalow attic insulation upgrade costs $2,500–$5,000 and eliminates the majority of ice dam formation.
Step 2 — Add Balanced Soffit and Ridge Ventilation
Insulation alone isn't enough if hot air is still trapped in the attic. Balanced ventilation — soffit vents at the eaves drawing cold air in, ridge vents at the peak exhausting warm air — keeps the attic temperature close to the outdoor temperature, even when the living space below is heated.
NBC 2020 requires a minimum 1:300 ratio of net free ventilation area to attic floor area. Many older Moncton homes have plugged or absent soffit vents, and ridge vents were not standard until the 1990s. A roofer can assess your ventilation during inspection and add what's needed during re-roofing.
Step 3 — Install Ice & Water Shield at All Eaves
Ice & water shield (IKO StormShield, CertainTeed Vycor, or Grace equivalents) is a self-adhesive membrane applied directly to the roof deck. It seals around every nail and staple, creating a watertight barrier that stops backed-up water from entering even if ice dams form.
NB building code requires ice & water shield at all eaves to a minimum of 1 metre past the interior wall line. It should also be installed in all valleys, around all penetrations (pipes, vents, skylights), and at all rakes. Every re-roofing project we complete includes this as standard — it is not optional in NB's climate.
Step 4 — Heated Gutter Cables for Chronic Problem Areas
For eaves or valleys that consistently form ice dams despite proper insulation and ventilation — often on north-facing slopes or at complex roof junctions — self-regulating heated cables (EasyHeat, HotEdge, Warmup) provide active prevention.
These cables are installed along the eave edge and through downspouts. They sense temperature and activate automatically at freezing, creating a channel for meltwater to drain. Professional installation costs $400–$1,200 depending on linear footage and complexity. They draw low wattage and are only active when temperatures are near freezing.