Single-ply roofs perform well through Ottawa winters when the seams, flashings and drains are detailed for cold. The membrane surface swings from below -30°C on a January night to well over 60°C on a black roof in July, and every detail has to survive that movement.
Cold-weather seaming. TPO and PVC can be welded in winter on a dry, frost-free surface, with the welder's heat and speed adjusted and a test weld cut and peeled before production. Many bonding adhesives and seam primers carry minimum application temperatures above freezing, so winter adhered EPDM means cold-weather products, heated storage or waiting for spring.
Snow load and drifting. The structure carries the snow, not the membrane, but drifts against parapets, penthouse walls and rooftop units concentrate the weight. Ontario's snow loading alert urges owners to watch for sagging and cracking, and our commercial roof maintenance programs include winter drain and drift checks.
Thermal movement. EPDM can shrink with age and tug on base flashings, so perimeter securement at every wall and curb is not optional. Reinforced TPO and PVC are more dimensionally stable, but long runs still need proper termination bars.
White or black? On offices with server rooms, labs or heavy lighting, a white TPO or PVC roof cuts summer cooling load noticeably. In winter, snow cover and a low sun mean a white roof gives up very little heating benefit.
