Roof Repair in Ottawa, ON

Roof repair in Ottawa is defined by two forces that exist nowhere else in Ontario at the same intensity: ice dams and heavy snow loads. Ottawa is arguably the ice dam capital of eastern Ontario. The city's geographic position — inland, north of the Great Lakes' moderating influence, subject to direct Arctic air outbreaks through the Ottawa Valley — means it gets more freeze-thaw cycles through winter than virtually any other major Canadian city. A single January week might see Ottawa go from -25°C to +2°C and back to -15°C, perfectly cycling through the conditions that generate ice dams.

Ice dams form when heat from a warmer attic (or sun warming the upper roof surface) melts snow at the roof field, and the meltwater refreezes at the cold eaves where it overhangs the exterior wall. As water backs up behind the ice dam, it finds its way under shingles, through nail holes, and eventually into the attic space and ceiling below. Ottawa homeowners in heritage neighbourhoods — the Glebe, Old Ottawa South, Sandy Hill — see more ice dam damage because these older homes were built before modern attic ventilation standards, have cathedral ceiling sections that are difficult to insulate adequately, and often have low-slope roof sections that trap backed-up water.

Flat or low-slope roofs are particularly problematic in Ottawa's climate. Many pre-war heritage homes in Centretown and the Glebe have partial flat roof sections over extensions, dormers, or bay windows. Flat roofs in Ottawa need to be built or rebuilt with Ottawa's climate in mind: proper membrane systems with fully adhered modified bitumen or EPDM, tapered insulation for positive drainage, and generous overhangs on adjacent sloped sections to shed snow away from the flat field. A flat roof repaired with the wrong product or inadequate slope correction will fail again within one to two Ottawa winters.

Snow loads are a structural concern on Ottawa roofs that homeowners often overlook until they hear cracking sounds during a heavy snow year. Ottawa regularly receives 200–250+ centimetres of snowfall per season, and a fully loaded wet-snow roof can exceed the design limit of older structures. Professional roofers in Ottawa will flag structural concerns they observe during repair work — ridge beam sag, rafter spread, or visible deflection in flat roof decking. These are not roofing repairs; they are structural repairs that require a structural assessment before roofing work proceeds.