Ice dam risk in Indiana, PA
Will your roof get ice dams in Indiana, PA?
13.3 dam days a winter
Moderate risk. On an ordinary house in Indiana, conditions for an ice dam come on about 13.3 days in a normal winter, mostly in January and February.
Indiana averages 46 inches of snow a year and about 49 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 Indiana
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 8.0 | Moderate |
| Typical, some insulation, not air-sealed | 13.3 | Moderate |
| Older or poorly insulated, warm attic | 20.0 | 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 20.0 days.
What to do about ice dams in Indiana
- 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.
Indiana winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 13.3 | 16.9 | 5.3 |
| February | 11.8 | 13.3 | 3.8 |
| March | 6.1 | 6.6 | 1.3 |
| April | 1.1 | 0.5 | 0.0 |
| November | 2.7 | 2.4 | 0.4 |
| December | 10.8 | 9.6 | 2.5 |
Indiana next to nearby towns
Indiana ranks 17 of 68 Pennsylvania cities here for ice-dam days, behind St. Marys at 26.9 days.
- Johnstown, PA 24 mi, 20.5 days
- Murrysville, PA 29 mi, 8.8 days
- Lower Burrell, PA 30 mi, 9.6 days
- Greensburg, PA 30 mi, 9.2 days
- New Kensington, PA 32 mi, 8.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Indiana 3 SE, 2.6 miles from Indiana. 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.