Torch-On vs. Metal Roofing: Which Lasts Longer in BC’s Rain?

When a Vancouver building owner is choosing a new low-slope roof, the choice often comes down to two proven options: torch-on (SBS-modified bitumen) or metal. Both can last for decades here — but they age very differently in our rain, and the right pick depends on your roof’s slope, budget and how long you plan to hold the building.

Torch-on roofing is the most common flat-roof system in the Lower Mainland for good reason. It is a multi-ply membrane, heat-welded at every seam, that creates a fully bonded waterproof layer built to shed constant rain. A properly installed torch-on roof typically lasts 20 to 30 years in our climate, and when a small issue does appear, it is straightforward and inexpensive to patch. That repairability is a real advantage over a roof’s life.

Metal roofing — standing-seam in particular — can outlast torch-on, often reaching 40 to 50 years. It sheds water fast, resists moss, and looks sharp on the right building. The trade-offs are a higher up-front cost and the fact that metal generally wants some slope to drain properly. On a truly flat roof, metal is usually the wrong tool; on a steep-slope or architectural building, it can be the best long-term value in the city.

In BC’s rain specifically, the deciding factor is rarely the material itself and almost always the detailing. Vancouver roofs don’t fail in the open field — they fail at the edges, penetrations and seams, where wind-driven rain and freeze-thaw movement attack flashing. A torch-on roof with meticulous flashing will outperform a metal roof with sloppy detailing, and vice versa. This is why we care as much about who installs the roof as what it is made of.

Moss is the other Vancouver reality. Our damp, shaded roofs grow moss readily, and it holds moisture against the surface. Metal resists it better; torch-on handles it fine with routine maintenance. Either way, an annual clean-and-inspect visit does more to extend a roof’s life here than almost any material upgrade.

So which lasts longer? Metal, on paper — but torch-on is often the smarter buy for a flat or low-slope Vancouver building when you weigh cost, repairability and how the roof actually performs in our weather. The right answer genuinely depends on your building.

If you are weighing the two, we are happy to walk your roof with you, explain what suits its slope and structure, and give you an honest recommendation and estimate — with no pressure to pick the pricier option.