Should I add ice and water shield to my garage roof in Riverview NB?

Yes, ice and water shield is strongly recommended for any garage roof in Riverview, and in fact it is partially required by the NB Building Code. At minimum, code requires a self-adhering ice and water shield membrane extending at least 36 inches up from the eave edge on all sloped roofs. However, given Riverview's specific climate conditions, most experienced NB roofers will recommend extending that coverage to 48 or even 72 inches from the eave.

Riverview sits in the Petitcodiac River valley, which brings a combination of heavy snowfall, frequent freeze-thaw cycles, and sustained cold that makes ice damming a serious concern on garage roofs. Ice dams form when heat escaping through the roof melts snow on the upper portion of the roof, and that meltwater refreezes at the colder eave edge. The resulting ice ridge traps water behind it, forcing it under shingles and into the roof sheathing. On an unprotected roof, this leads to rot in the plywood decking, water stains on the garage ceiling, and potential mould growth that you may not discover for years. Ice and water shield is a rubberized, self-sealing membrane that prevents this water from reaching the sheathing even when it gets past the shingles.

Why Extra Coverage Makes Sense in Riverview

For a typical garage roof in the Riverview area, the cost of upgrading from the code-minimum 36-inch eave coverage to full coverage on the lower 4-6 feet of the roof adds only $300 to $600 in materials for a two-car garage. Considering the cost of repairing water-damaged roof sheathing and trusses — easily $2,000 to $5,000 or more — the extra membrane is one of the best-value upgrades you can make during a garage build or re-roof.

There are a few specific situations where you should consider even more aggressive ice and water shield coverage. If your garage has a low-slope roof (4/12 pitch or less), the entire roof deck should be covered because low-slope roofs are far more vulnerable to wind-driven rain and ice dam backup. If your attached garage has a valley where the garage roof meets the house roof, that entire valley should be lined with ice and water shield from top to bottom, as valleys concentrate both water flow and snow accumulation. Similarly, any area where a garage roof meets a vertical wall — common on attached garages — needs ice and water shield extending at least 24 inches up the wall and out onto the roof surface.

When choosing an ice and water shield product, look for a self-adhering membrane with a minimum thickness of 40 mils. Grace Ice & Water Shield, Blueskin, and Resisto are common brands available through NB building supply stores. The product should be applied directly to clean, dry roof sheathing before any roofing felt or synthetic underlayment is installed, and it must be installed when temperatures are above 5 degrees Celsius for proper adhesion — another reason to time your garage build during the warmer months.

One important note: ice and water shield is a secondary defence, not a substitute for proper attic ventilation and insulation. If your garage is heated or insulated, ensuring adequate soffit-to-ridge ventilation is the primary way to prevent ice dams from forming in the first place. The membrane is your backup protection for when conditions overwhelm even a well-ventilated roof, which happens regularly during NB's heaviest winters.

For a project like this, your roofer should be specifying the ice and water shield coverage as part of their quote. If a contractor's quote only mentions the code-minimum 36 inches, ask them to price the extended coverage — any experienced NB roofer will understand exactly why you are asking. If you are planning a new garage build or re-roof in the Riverview area, New Brunswick Garages can match you with local contractors who understand these Maritime climate requirements.