Your attic needs a steady flow of outside air: cool air in low at the soffits, warm moist air out high at the ridge. When that balance is off, heat bakes the shingles in summer, moisture condenses on the underside of the deck in winter and warm attic air melts snow that refreezes at the eaves as ice dams. Hammerline Roofing assesses and corrects attic ventilation on its own or as part of a roof replacement.

Ventilation work we do

Ridge vents — a continuous vent along the peak that lets warm air escape evenly along the whole roof.
Soffit intake — vented soffit panels and clear baffles so insulation doesn't block air coming in (see soffit and fascia).
Box and roof vents — static vents where a ridge vent isn't practical, sized to the attic.
Bath and kitchen fan venting — fans ducted all the way outside instead of into the attic, a common cause of attic moisture.
Mixed-vent corrections — removing competing exhaust vents that short-circuit airflow.

Signs your ventilation needs work

Ice dams along the eaves every winter, especially with icicles hanging from the eavestroughs.
Frost or dampness on the underside of the roof deck or on nails in the attic during cold weather.
Mould or dark staining on the attic sheathing.
Very hot upper floors in summer, and shingles that are aging faster than they should.

Ventilation works together with attic insulation and air sealing, so we look at all three. If an ice dam has already caused a leak, see roof repair.

Good to know

Ventilation is easiest and least expensive to fix during a roof replacement, when the deck is open and a continuous ridge vent can be cut in. If your roof still has years left, many problems can still be improved now by clearing soffits, adding baffles and venting bathroom fans properly. Be cautious about adding powered attic fans without checking the house first: they can pull conditioned air and even exhaust gases from the living space. We look at the whole attic before recommending any change.

What affects the cost of roof ventilation

Ventilation costs depend on what your attic has now and what it needs. Adding a ridge vent during a roof replacement costs far less than retrofitting one later. Opening up blocked soffits, installing baffles or adding vented soffit panels adds labour at the roof edge. Venting bathroom fans properly to the outside may involve new ducting and a roof or wall cap. Removing competing vents and patching the roof is a small cost that pays off in better airflow. Attic insulation or air sealing, if needed, is quoted as a separate line.