Ice dam risk in Phoenixville, PA
Will your roof get ice dams in Phoenixville, PA?
8.7 dam days a winter
Moderate risk. On an ordinary house in Phoenixville, conditions for an ice dam come on about 8.7 days in a normal winter, mostly in February and January.
Phoenixville averages 13 inches of snow a year and about 34 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 Phoenixville
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 6.3 | Moderate |
| Typical, some insulation, not air-sealed | 8.7 | Moderate |
| Older or poorly insulated, warm attic | 11.6 | Moderate |
Sealing and insulating a typical attic takes out about 2.3 days a winter here. It does not move the risk band, but it shortens every dam.
What to do about ice dams in Phoenixville
- 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.
Which to spend on first: air sealing or heat cable.
Phoenixville winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 3.9 | 10.6 | 3.1 |
| February | 5.4 | 14.2 | 3.7 |
| March | 1.3 | 4.2 | 0.8 |
| April | 0.1 | 0.1 | 0.0 |
| November | 0.0 | 0.5 | 0.1 |
| December | 2.2 | 4.2 | 1.0 |
Phoenixville next to nearby towns
Phoenixville ranks 41 of 68 Pennsylvania cities here for ice-dam days, behind St. Marys at 26.9 days.
- Norristown, PA 10 mi, 3.3 days
- Pottstown, PA 10 mi, 8.7 days
- West Chester, PA 13 mi, 8.5 days
- Lansdale, PA 15 mi, 4.6 days
- Lansdowne, PA 19 mi, 3.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Graterford 1 E, 8.3 miles from Phoenixville. 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.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.