Ice Dam Risk Calculator
Enter your attic insulation R-value, the coldest sustained outside temperature, and your roof pitch. Results update instantly — the score combines all three factors into a 0–100 ice dam risk rating.
Ice dam risk score based on insulation, temperature, and roof pitch.
Insulation factor
Heat loss through the attic
Temperature factor
How cold it stays outside
Pitch factor
How long snow sits on the roof
What your score means
Low risk (0–24): your attic setup sheds heat and snow well. Moderate risk (25–49): add insulation and seal attic air leaks. High risk (50–74): clear snow from the lower roof with a rake and watch the eaves. Severe risk (75–100): take action before the next storm — professional snow removal and an inspection are recommended.
How Ice Dams Form and How to Stop Them
Ice dams are ridges of ice that build up at the eaves of a roof. They form when warm air from the living space leaks into the attic and melts snow on the upper roof. The meltwater runs down the roof slope until it hits the cold eaves — which hang past the heated space — and refreezes. Over hours or days, the ice ridge grows taller, damming meltwater behind it. That trapped water backs up under the shingles and can soak the attic, ceilings, walls, and insulation.
Oklahoma's winter storms are often followed by sharp cold snaps, which is the perfect setup: a few inches of snow on the roof, then a week of nights in the teens. That is why the three inputs on this calculator — attic insulation, outside temperature, and roof pitch — matter more than any other factors.
- R-value under R-30: too much heat reaches the roof deck. The melt-freeze cycle starts within hours. (Up to 45 points of risk)
- Temperatures below 20°F: meltwater refreezes fast at the eaves. Sustained cold is what builds thick dams. (Up to 35 points of risk)
- Pitches below 4/12: snow sits longer and meltwater crawls slowly, giving the ice time to stack up. (Up to 20 points of risk)
| Factor | Low risk | High risk |
|---|---|---|
| Attic insulation | R-38 or higher (10 pts or less) | R-19 or less (38–45 pts) |
| Outside temperature | Above 32°F (0 pts) | Below 10°F (29–35 pts) |
| Roof pitch | 8/12 or steeper (3–6 pts) | 2/12 to 4/12 (15–20 pts) |
The cheapest fixes come first: air-seal the attic (recessed lights, plumbing vents, attic stairs), top up insulation toward R-49, and keep gutters clear. If your score stays high after that, add roof and soffit venting so the roof deck stays cold — a cold deck is the goal, not a warm one.
Ice Dam FAQ
Ice dams form when heat escaping from the attic melts snow on the upper part of the roof. The meltwater runs down to the cold eaves, where it refreezes into a ridge of ice. As the ice ridge grows, it dams meltwater behind it, and that trapped water backs up under the shingles and can leak into the attic, walls, and ceilings. The three big contributors are poor attic insulation, air leaks, and outside temperatures that stay below freezing for days.
Oklahoma's energy code recommends attic insulation at R-38 or higher, and R-49 to R-60 is a common upgrade target. If your attic has less than R-30 (roughly 9-10 inches of fiberglass or cellulose), heat loss through the ceiling is high enough to feed ice dams during cold snaps. The calculator scores R-38 and above as low-risk.
Low-slope roofs in the 2/12 to 4/12 range are the most vulnerable because snow sits on the roof longer and meltwater moves slowly. Steeper roofs above 8/12 shed snow more readily, which reduces both snow load and ice dam formation. Roof pitch is one factor, but a steep roof with poor insulation can still ice-dam.
For ground-level roofs, a roof rake can remove the bottom 3-4 feet of snow to break the cycle. Calcium chloride ice melt in a pantyhose laid across the dam can cut channels — never use salt, an axe, or a chisel, which damage shingles. For second-story roofs, steep slopes, or thick dams, call a professional like Proof Construction; we offer ice dam removal and roof de-icing in the Tulsa area. See what ice dam removal costs.
Most standard homeowners policies cover the water damage that results from ice dams (such as interior ceiling, wall, and insulation damage) under named-peril coverage. Coverage for the roof covering itself varies by policy and carrier. Take photos before any cleanup, keep receipts, and call your carrier early. Proof Construction helps Tulsa-area homeowners document damage and file claims; call (918) 734-4444. Get a free roof estimate from Proof Construction. Explore all roofing solutions from Proof Construction. Prepare with roof winterization.