Ice dam risk in Ellensburg, WA
Will your roof get ice dams in Ellensburg, WA?
6.9 dam days a winter
Moderate risk. On an ordinary house in Ellensburg, conditions for an ice dam come on about 6.9 days in a normal winter, mostly in January and December.
Ellensburg averages 20 inches of snow a year and about 26 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 Ellensburg
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 4.9 | Low |
| Typical, some insulation, not air-sealed | 6.9 | Moderate |
| Older or poorly insulated, warm attic | 9.6 | Moderate |
Sealing and insulating a typical attic takes out about 2.1 days a winter here. It drops the risk from moderate to low.
Preventing ice dams on a Ellensburg 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.
Ellensburg winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.2 | 10.9 | 3.0 |
| February | 2.7 | 3.9 | 0.9 |
| March | 0.6 | 0.3 | 0.1 |
| October | 0.1 | 0.1 | 0.0 |
| November | 3.0 | 1.5 | 0.3 |
| December | 7.7 | 9.4 | 2.7 |
Ellensburg next to nearby towns
Ellensburg ranks 10 of 91 Washington cities here for ice-dam days, behind Spokane at 13.0 days.
- Yakima, WA 28 mi, 6.9 days
- East Wenatchee, WA 31 mi, 7.6 days
- Wenatchee, WA 32 mi, 7.6 days
- Sunnyside, WA 54 mi, 5.5 days
- Grandview, WA 60 mi, 5.5 days
Where these numbers come from
NOAA 1991–2020 climate normals from Yakima Airport, 30.1 miles from Ellensburg. 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.
- The weather station is 30 miles away, far enough that local snow can differ.