Ice dam risk in Roanoke, VA
How often ice dams form in Roanoke
1.7 dam days a winter
Low risk. On an ordinary house in Roanoke, conditions for an ice dam come on about 1.7 days in a normal winter, mostly in February and January.
Roanoke averages 15 inches of snow a year and about 11 days with snow on the ground. Most of it comes and goes within a few days. The conditions that make a dam need all three at once: snow, cold at the eave and heat above it.
What your attic does to that number in Roanoke
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 1.4 | Low |
| Typical, some insulation, not air-sealed | 1.7 | Low |
| Older or poorly insulated, warm attic | 2.0 | Low |
The attic matters less in Roanoke than in colder towns: there are only 0.3 days a winter between a typical attic and a sealed one.
Preventing ice dams on a Roanoke roof
- Check the gutters before the first snow and clear them, so meltwater has somewhere to go. If you see icicles thicker than a finger along the eave after a storm, that is the early sign to look at the attic.
Snowy places are not always the worst: why snowfall misleads.
Roanoke winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 4.3 | 3.2 | 0.6 |
| February | 4.8 | 3.7 | 0.6 |
| March | 2.3 | 1.1 | 0.1 |
| April | 0.1 | 0.1 | 0.0 |
| November | 0.1 | 0.0 | 0.0 |
| December | 3.2 | 2.4 | 0.4 |
Roanoke next to nearby towns
Roanoke ranks 19 of 39 Virginia cities here for ice-dam days, behind Winchester at 4.7 days.
- Salem, VA 5 mi, 1.7 days
- Blacksburg, VA 26 mi, 4.5 days
- Christiansburg, VA 26 mi, 4.3 days
- Radford, VA 35 mi, 4.3 days
- Martinsville, VA 41 mi, 0.5 days
Where these numbers come from
NOAA 1991–2020 climate normals from Roanoke-Blacksburg Regional Airport, 2.8 miles from Roanoke. A dam day is a day with snow on the roof and freezing at the eave while heat or sun melts the snow above it. This describes a normal winter, not this one.