In the wet climate of Vancouver, British Columbia, several specific environmental and maintenance factors contribute to roof leaks. According to Paragon Roofing BC, the primary causes include:

Local Weather and Environmental Factors

• Heavy Rainfall and Flooding: Intense precipitation can overwhelm drainage systems, leading to water pooling on flat or low-slope roofs and seeping through seams.
• Wind Damage: Strong coastal winds can crack metal flashing around chimneys and vents, which is a frequent failure point for roof integrity.
• Moss and Algae Growth: Vancouver’s high humidity fosters moss buildup, which traps moisture against the roof surface and causes materials like shingles and cedar shakes to decay over time.
• Freeze-Thaw Cycles: These temperature fluctuations accelerate the aging of roofing materials.

Maintenance and Structural Issues

• Clogged Gutters: Fallen leaves and debris from storms cause water backups that force moisture under the roof structure.
• Material Fatigue: Aging shingles may experience granule loss, warping, or curling, which creates gaps for water entry.
• Damaged Sealants: Cracks in the sealant around roof penetrations like skylights, vents, and chimneys allow water to infiltrate.
• Poor Ventilation: Inadequate attic ventilation can lead to condensation-related damage and moisture buildup.