How the sealing strip works

Most shingles carry a strip of thermally activated adhesive on the underside. After installation, warmth from the sun softens this strip so adjacent shingles bond together, which is what resists wind uplift. In cold weather that bond forms slowly, and shingles installed during a cold spell may not seal until temperatures rise in spring.

Winter installation practice

When work proceeds in cold conditions, installers commonly take extra steps so the roof stays secure until the adhesive activates:

  • Hand-sealing individual shingles with a compatible roofing cement at the manufacturer's specified spots.
  • Handling bundles carefully, since cold shingles are more brittle and can crack if bent sharply.
  • Following the fastener pattern intended for higher wind exposure where the site calls for it.
Practical note

Manufacturers publish minimum application temperatures and hand-sealing instructions on the product wrapper and data sheet. Those instructions take priority over any general guidance.

Ice dams and the eaves

The most common cold-weather failure point is the eave, where ice dams form. Heat escaping into the roof melts snow higher up; the meltwater runs down and refreezes over the colder overhang. As ice builds, water can pond behind it and work back under the shingles.

Two defences are widely used together. A self-adhering membrane is applied along the eaves and in valleys to seal around fasteners and block backed-up water. Separately, improving attic insulation and ventilation keeps the roof deck cold so less snow melts in the first place.

Slope matters

Asphalt shingles are designed for sloped roofs. On shallow pitches the risk of wind-driven water getting under the shingles rises, so manufacturers specify a minimum slope and additional underlayment below it. For very low or flat sections, a different covering is usually more appropriate.

Routine maintenance

  1. Inspect after major storms for lifted, cracked, or missing shingles.
  2. Keep gutters and downspouts clear so meltwater drains rather than pooling at the eaves.
  3. Watch for granule loss collecting in gutters, which can indicate aging of the surface.
  4. Check flashing at chimneys, vents, and walls, since these joints often fail before the field shingles do.
Authoritative reference

For code-level requirements on roofing and ice protection in Canada, consult the National Research Council Canada codes publications.