Poor attic ventilation is one of the most common causes of premature roof failure in Surrey BC — and one of the most misdiagnosed. Most homeowners assume moisture, shingles, or flashing caused their problem. In many cases, the root cause is trapped heat and humidity in the attic that degrades materials from the inside out.

Ventilation inspection and repair: 236-838-9577 — I-M Roofing, Surrey BC.

How Roof Ventilation Works

A properly ventilated attic uses intake vents at the soffit (eave level) and exhaust vents at the ridge. Cooler outside air enters at the bottom, pushes warm/humid air upward, and exhausts it at the top. This keeps the attic within 5°C of the outdoor temperature in both summer and winter.

BC Building Code requires 1 sq ft of net free ventilation area per 300 sq ft of attic floor (when vapour barrier is present) or 1:150 without a vapour barrier. Most Surrey BC homes built before 2005 are under-ventilated by code standards.

Signs of Poor Ventilation in Surrey BC Homes

• Ice dams on the eave — heat escaping through the attic melts snow, which refreezes at the cold overhang, forcing water back under shingles
• Shingles aging faster than expected — heat trapped in the attic cooks the underside of shingles, destroying the asphalt binders years early
• Mould or mildew in the attic — condensation in a poorly ventilated space creates ideal conditions for mould growth
• High energy bills in summer — a 60°C attic radiates heat into living spaces, forcing AC to work harder
• Frost on the attic underside in winter — moisture from the house is condensing in the attic instead of exhausting

Ventilation Fix Costs — Surrey BC 2026

Related Services

• Roof Inspection Surrey BC — includes attic ventilation assessment
• Roof Replacement Surrey BC — new installations include ventilation upgrade
• Licensed Roofer Surrey BC — WorkSafeBC registered, $5M liability

Call 236-838-9577 to book an attic ventilation inspection across Surrey BC.