Attic Ventilation When You Replace a Roof in Western Massachusetts

In at the bottom, out at the top

A vented attic draws cool outside air in through the soffits or eaves and lets warm, moist air out near the ridge. The building code calls for a balance between intake and exhaust. When the intake is blocked, the exhaust vents pull air from wherever they can, including from the house below.

Why it matters around Springfield

Western Massachusetts winters are long and cold. Warm, humid air leaking up from the house hits cold roof boards and condenses. Over several winters that can stain and soften the decking, rust nails and grow mold. Heat in the attic also melts snow on the roof, which refreezes at the cold eaves as ice dams.

Summers bring the opposite problem. An attic without airflow gets very hot, which bakes asphalt shingles from below and pushes heat into top-floor rooms.

Warning signs in the attic

• Frost on nail tips or the underside of the roof boards on cold mornings
• Dark stains or growth on the decking, often on the north side
• Damp or matted insulation
• Insulation stuffed against the eaves, blocking the soffits
• Bath or kitchen fans that end in the attic instead of outside
• Icicles and ice dams along the same eaves every winter

What can change during a replacement

• A continuous ridge vent cut along the peak
• Old box vents, turbines or gable fans closed off so they do not compete with the ridge vent
• Soffit vents added or cleared, with baffles to keep insulation off the eaves
• Damaged decking replaced before the new roof goes on

Older and unusual houses

Many Springfield Victorians and Colonials have finished third floors, kneewalls and cathedral ceilings with little or no attic space. Triple-deckers often have a shallow space under a flat roof. Those roofs need a different approach, sometimes vented channels under the deck or insulation above it. See triple-decker roof replacement and flat roof options.

Questions to ask the roofer

1. Will you look in the attic before the job?
2. How will intake and exhaust be balanced?
3. Which existing vents will be closed off?
4. Will baffles be installed at the eaves?
5. Does the shingle maker set any ventilation requirements for this product?