Ice dam risk in Washington, PA
Will your roof get ice dams in Washington, PA?
11.6 dam days a winter
Moderate risk. On an ordinary house in Washington, conditions for an ice dam come on about 11.6 days in a normal winter, mostly in January and February.
Washington averages 32 inches of snow a year and about 41 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 Washington
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 6.3 | Moderate |
| Typical, some insulation, not air-sealed | 11.6 | Moderate |
| Older or poorly insulated, warm attic | 18.3 | High |
Sealing and insulating a typical attic takes out about 5.3 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 18.3 days.
Preventing ice dams on a Washington 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.
Washington winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 9.9 | 13.6 | 4.5 |
| February | 7.5 | 12.0 | 3.6 |
| March | 6.1 | 5.7 | 1.1 |
| April | 0.6 | 0.3 | 0.0 |
| November | 1.8 | 1.7 | 0.2 |
| December | 6.0 | 8.0 | 2.2 |
Washington next to nearby towns
Washington ranks 21 of 68 Pennsylvania cities here for ice-dam days, behind St. Marys at 26.9 days.
- Bethel Park, PA 15 mi, 11.6 days
- Jefferson Hills, PA 18 mi, 6.0 days
- Whitehall, PA 19 mi, 8.8 days
- Baldwin, PA 21 mi, 8.8 days
- West Mifflin, PA 22 mi, 8.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Washington 3 NE, 3.1 miles from Washington. 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.