What are the Common Drainage Issues on Vancouver Roofs?

In Vancouver’s unique climate, several common drainage issues frequently affect residential and commercial properties. Due to the region’s high annual rainfall and specific neighborhood characteristics, the most prevalent issues include:

1. Clogged Gutters and Downspouts: This is a major concern in suburban areas like Surrey, where longer roof spans and heavy foliage lead to leaf accumulation and debris blockages.
2. Ponding and Pooling: This is common on flat or low-slope roofs, particularly in high-density areas like Downtown Vancouver. It is often caused by intense rainfall and inadequate roof pitch.
3. Rapid Runoff and Erosion: In sloped areas like North Vancouver, steep terrain can exacerbate water flow, leading to soil erosion if downspouts are misplaced or not extended properly.
4. Ice Damming: Despite mild winters, freeze-thaw cycles can create ice dams that cause leaks along roof edges.
5. Inadequate Pitch: Many low-slope roofs suffer from poor drainage because they lack the minimum 2 percent pitch required by the BC Building Code to ensure proper water shedding.
6. Structural Signs of Failure: If drainage is restricted, homeowners may notice interior water stains, curling shingles, attic mold, or puddling water near the foundation.