Ice dams form on New York and Connecticut roofs every winter when heat escaping from a warm attic melts roof snow, the meltwater runs down to a cold eave, and refreezes. The resulting ridge of ice backs water under shingles and into the house. The long-term fix is not a heat cable or a roof rake — it is a properly air-sealed, insulated, and ventilated attic combined with a correctly installed ice-and-water shield at the eaves. Gunner Roofing addresses all three layers on every roof replacement in the NY and CT service area.
What Causes an Ice Dam
Three conditions must occur simultaneously for an ice dam to form (per InterNACHI):
- Snow on the roof. The raw material that melts.
- Upper-roof surface above 32°F. Heat escaping from a poorly insulated or air-leaky attic warms the roof deck and melts the snow from below.
- Eave surface at or below 32°F. The eave overhangs the exterior wall and has no warm attic air beneath it, so it stays cold. Meltwater reaches this zone and refreezes.
The dam grows with each melt-freeze cycle. Meltwater pooling behind it has nowhere to go but under the shingles. Solar gain can also trigger melt even when outdoor temperatures are well below freezing, by warming the dark roof surface directly.
Why NY and CT Are High-Risk
Westchester County and Fairfield County sit in an inversion zone for this problem. Winters produce heavy, persistent snowpack — often a week or more between thaws — and interior heating keeps attic temperatures elevated. Per Connecticut’s adopted 2021 IRC (Table R301.2), the entire state is designated as an ice-barrier-required region, with a winter design temperature as low as 2°F and a frost line depth of 42 inches. That designation reflects real exposure, not administrative caution.
What Ice Dams Actually Damage
Ice dams are not just cosmetic. Water backing under shingles rots OSB or plywood roof decking from within — by the time a stain appears on the ceiling, the deck may already need replacement. Attic insulation that gets repeatedly wetted permanently loses R-value and does not fully recover even after drying (per InterNACHI). Water that reaches framing and ceiling joists causes structural rot and mold. The weight of ice dams routinely tears gutters off the fascia. Interior ceiling stains and peeling paint are visible symptoms that typically appear only after hidden damage is already underway.
The Three-Layer Fix: Air Sealing, Insulation, Ventilation
No single measure eliminates ice dams. Roof-mounted heat cables manage the symptom (see below); they do not address the root cause. Durable prevention requires getting the attic thermal boundary right.
1. Air Sealing — The Most Important Step
Heat does not just conduct through insulation — it convects through gaps. Every unsealed penetration through the ceiling (recessed light canisters, plumbing chases, attic hatches, top-plate gaps, wiring holes) is a direct path for conditioned air to reach the attic and warm the roof deck.
Air sealing must happen at the attic floor, not at the rafters, to keep the attic itself cold and unconditioned. Common bypass points include recessed light canisters, attic hatches, plumbing and exhaust penetrations, knee-wall cavities in cape-style homes, and top-plate gaps in balloon-framed older homes — the type common in Westchester and Fairfield County neighborhoods built before the 1960s.
2. Insulation — Keep the Heat Where It Belongs
Once bypasses are sealed, adding insulation depth to the attic floor keeps residual heat from conducting into the roof assembly. Connecticut’s 2021 IRC (Table N1102.1.2) sets a maximum ceiling assembly U-factor of 0.024 for Climate Zone 5A — equivalent to approximately R-49 under the prescriptive compliance path. Many existing homes in the region fall well short of this target, especially those built before modern energy codes.
The key principle: the attic should be cold in winter. If snow is melting off the upper roof while outdoor temperatures are below freezing, the attic is warm and the insulation is inadequate.
3. Ventilation — Flush Out Attic Heat
Proper soffit-to-ridge ventilation flushes any heat that does make it into the attic before it can warm the deck significantly. The soffit provides cool intake air; the ridge vent (or other high exhaust) lets warm air escape. Both components must be unobstructed — insulation baffles prevent blown-in insulation from blocking the soffit inlets.
Note: ventilation alone cannot compensate for a poorly air-sealed or under-insulated attic. It is the third line of defense, not the first.
What Gunner Does on Every Roof Replacement
When Gunner Roofing replaces a roof in New York or Connecticut, the installation addresses ice dam risk at the roof assembly level regardless of what the homeowner does or does not do in the attic.
Ice-and-water shield at the eaves. Per IRC §R905.1.2 — adopted as Connecticut’s 2021 Residential Code and as Section R905.1.2 of the 2020 Residential Code of New York State — in areas with a history of ice forming along the eaves, an ice barrier (a self-adhering polymer-modified bitumen membrane) must extend from the lowest roof edge to not less than 24 inches inside the exterior wall line of the building. Gunner installs ice-and-water shield to meet or exceed this minimum on every job in the NY and CT service area.
Full-valley coverage. Valleys are a secondary ice-dam entry point. Gunner runs leak barrier through all valleys in addition to the eave protection.
Dormer and penetration detailing. Step flashing, counter-flashing, and leak-barrier integration at every dormer, chimney, skylight, and wall termination close off the other paths water takes when it backs up.
Gunner installs leak barrier in the valleys and step and counter-flashing at penetrations and sidewalls as standard practice on every roof replacement. As a GAF Master Elite contractor, Gunner also offers the enhanced GAF Golden Pledge® and Silver Pledge™ system warranties as an opt-in tier; those warranties call for enhanced leak-barrier coverage beyond the code minimum (per the GAF Steep-Slope Pro Field Guide).
Gunner is a GAF Master Elite® 3-Star President’s Club contractor. Fewer than 3% of roofing contractors nationally qualify for Master Elite® status (per GAF), and that designation includes accountability on system-level installation details that non-certified contractors may skip.
When the Attic Is the Problem
A new roof alone does not fix a bad attic. If a homeowner has recurring ice dams and the previous roof had proper ice-and-water shield, the attic thermal boundary is the culprit. In those cases, Gunner addresses the attic as part of the project — correcting problem areas such as blocked soffits, missing baffles, and uninsulated hatches, and improving the air sealing, insulation, and ventilation so the dams stop forming.
We identify the root cause and correct it — air sealing, insulation, and ventilation — instead of just patching the symptom.
Heat Cables: A Last Resort, Not a Solution
Self-regulating electric heat cables installed in a zigzag pattern along the eave create a melt channel that lets water drain before it refreezes. They do not prevent dam formation on the rest of the roof, and they require power, annual inspection, and periodic replacement. Most roofing professionals treat them as a short-term workaround rather than a permanent fix.
Use heat cables only as a short-term bridge while attic and roof work is planned, or on sections of roof where architectural constraints make a full thermal fix impractical (some low-pitch transitions over additions, for example).