Dangers Your Roof Might Face This Winter

Winter in New York isn’t postcard-pretty for roofs. It’s a three-round fight against physics. Below are the biggest seasonal threats we see on flat and pitched roofs from Riverdale to Rockaway, plus the exact steps we take to neutralize them.

Ice Dams: The Silent Gutter Killer

When attic warmth melts rooftop snow, water runs to the cold eave and refreezes, forming a dam that lifts shingles and backs water into bedrooms. Prevention starts in the attic: we verify R-49 to R-60 cellulose or fiberglass insulation and seal bypasses around plumbing stacks and party walls. On the exterior, we install self-adhered Ice & Water Shield 24″ inside the warm wall line and heat-trace critical downspouts. Result: no dam, no leak, no 3 a.m. bucket brigade.

Freeze-Thaw “Scaffolding”: How Spalling Starts

Small fissures in parapet mortar or chimney crowns suck up meltwater like a sponge. When temps dip below 32 °F overnight, that water expands, popping off face bricks (called spalling). One spalled brick exposes the next, and soon the whole coping is compromised. Our masons repoint with Type N mortar mixed with a latex bonding agent and cap the crown with an elastomeric membrane that stays flexible to -20 °F.

The 800-lb Snow Load

A single foot of fresh powder weighs ≈ 5 psf; wet, consolidated snow can hit 20 psf. Multiply by 1,000 sf of roof and you’re parking a city bus overhead. Most post-war Queens homes are rated for 40 psf, but aging rafters and previous remodels can halve that. We calculate live loads per ASCE 7-22 and, when needed, install attic sister joists or steel strongbacks from the ridge to the bearing wall. For flat roofs, we deploy plastic shovels and calcium-magnesium acetate, never rock salt that eats EPDM seams.

Bonus Tip: Condensation in the Attic

When indoor humidity meets a -5 °F underside of the roof deck, you get frost that “rains” in the attic come January thaw. We add ridge-to-soffit ventilation (1 sf NFA per 150 sf attic) and vapor-retarder ceiling paint to keep the attic air within 5 °F of ambient.

Winter waits for no one. Book Roof ON NYC pre-winter tune-up before the first flake: we’ll clear the gutters, tune the ventilation, and shoot drone IR images to confirm zero moisture intrusion. Call (929) 720-4223 and we’ll lock in your appointment within 48 hours.