Roofs in St. Louis face a winter threat that Sun Belt homes never see: ice dams. For homeowners in Ladue, Frontenac, Town and Country, and Clayton, understanding them is the key to avoiding expensive winter leaks.
How an ice dam forms
When heat leaks from the living space into the attic, it warms the roof deck and melts the snow on the upper roof. That meltwater runs down to the cold eaves and overhangs, where it refreezes into a growing ridge of ice. Water pooling behind that ice dam then backs up under the shingles and into the home. The damage — stained ceilings, wet insulation, rotted decking — often shows up mid-winter.
The real fix is inside the attic
Ice dams are a building-science problem, not just a roofing one. The cure is keeping the roof deck cold: air-seal and insulate the attic floor so heat stays in the house, and provide balanced intake and exhaust ventilation so the deck stays near outdoor temperature. A roof that stays cold doesn't melt snow unevenly, and dams don't form.
What the roof itself should include
During any replacement in the St. Louis climate, ice-and-water shield membrane belongs at the eaves and in the valleys — it's the backup that keeps backed-up water out even if a dam forms. Metal and slate roofs also shed snow more readily than shingles.
Don't chip at the ice
Hacking at an ice dam with tools damages the roof. If you have active leaking, address the immediate water and call a professional; then fix the root cause before the next winter.
Get a winter-readiness inspection
Trophy Exteriors inspects attic insulation, ventilation, and roof detailing across the St. Louis area — free, with honest recommendations to keep your roof dry through Missouri winters.
Frequently Asked Questions
What causes ice dams on a St. Louis roof?
Heat escaping into the attic melts snow on the upper roof; the meltwater refreezes at the cold eaves, building a dam of ice that backs water up under the shingles. Poor attic insulation and ventilation are the root cause.
How do I prevent ice dams?
Air-seal and insulate the attic floor, ensure balanced attic ventilation to keep the roof deck cold, and install ice-and-water membrane at the eaves during any roof replacement.
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