Cold Weather Roofing

Roofing materials are designed to be installed within certain temperature ranges. In cold weather, asphalt shingles become stiff and brittle, factory sealant strips do not bond, adhesives cure slowly, self-adhered membranes lose tack and hot bitumen cools before it bonds. Roofing still continues through winter in many cold regions, but crews adjust materials, methods and scheduling.

Asphalt shingles

• Sealant activation. Factory sealant strips rely on sun and warmth to bond. Shingles laid in cold weather may stay unsealed until warmer weather arrives and are vulnerable to wind in the meantime; manufacturers' instructions say when hand sealing is needed.
• Hand sealing. Where shingles will not self-seal soon, dabs of asphalt plastic cement (ASTM D4586 or similar) are placed under each tab or along the lower edge of laminated shingles, in the size and number the manufacturer specifies. Too much cement causes blistering.
• Handling. Store bundles in a warm place and bring them to the roof as needed. Bend ridge caps carefully; Canadian guidance suggests nailing one side first, then bending the cap over, and waiting for warmer weather or warming the caps if they still crack.
• Nailing. Cold shingles crack more easily when nails are overdriven, so nailer pressure is checked.

Membranes and bitumen

Canadian guidance notes that in cold weather bitumen may need heating close to its flash point to reach application temperature, but overheating degrades it; that felts must be fully bonded before the bitumen cools; and that each adhesive has temperature, humidity and wind limits that change drying and cure times. Modified bitumen rolls are stored in heated, dry space and brought up only as needed; torching is slower in cold, humid conditions.

Self-adhered products

Self-adhered underlayments and ice barriers have minimum application temperatures, and substrate temperature affects their bond. Some manufacturers require primers or heat guns in cold conditions.

Site practice

• Remove frost, ice and snow from decks before roofing; decks must be dry.
• Protect workers from cold stress and slippery surfaces.
• Install temporary membranes or night seals at the end of every working day.
• Schedule work around shorter daylight hours.