Ice dam risk in Rock Springs, WY
How often ice dams form in Rock Springs
13.9 dam days a winter
Moderate risk. On an ordinary house in Rock Springs, conditions for an ice dam come on about 13.9 days in a normal winter, mostly in January and December.
Rock Springs averages 31 inches of snow a year and about 44 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 Rock Springs
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 8.2 | Moderate |
| Typical, some insulation, not air-sealed | 13.9 | Moderate |
| Older or poorly insulated, warm attic | 20.9 | High |
Sealing and insulating a typical attic takes out about 5.7 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 20.9 days.
Preventing ice dams on a Rock Springs roof
- Air-seal the attic floor: the gaps around the hatch, light fixtures, plumbing stacks and the top plates of interior walls. This is the fix that removes the cause, and it usually costs less than a season of contractor ice removal.
- Rake the bottom three or four feet of roof after any storm that leaves more than about six inches, from the ground with a roof rake.
Which to spend on first: air sealing or heat cable.
Rock Springs winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.1 | 14.2 | 4.8 |
| February | 5.8 | 8.3 | 2.6 |
| March | 4.4 | 2.9 | 0.7 |
| April | 1.9 | 0.5 | 0.1 |
| May | 0.5 | 0.1 | 0.0 |
| October | 2.3 | 0.8 | 0.1 |
| November | 3.8 | 3.8 | 0.9 |
| December | 6.5 | 13.1 | 4.6 |
Rock Springs next to nearby towns
Rock Springs ranks 9 of 11 Wyoming cities here for ice-dam days, behind Jackson at 50.0 days.
- Green River, WY 14 mi, 23.1 days
- Vernal, UT 81 mi, 20.9 days
- Evanston, WY 93 mi, 32.8 days
- Riverton, WY 108 mi, 25.7 days
- North Logan, UT 134 mi, 23.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Rock Springs Fire Dept, 1.5 miles from Rock Springs. 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.