Ice dam risk in Franklin, IN
Will your roof get ice dams in Franklin, IN?
6.0 dam days a winter
Moderate risk. On an ordinary house in Franklin, conditions for an ice dam come on about 6.0 days in a normal winter, mostly in January and February.
Franklin averages 17 inches of snow a year and about 22 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 Franklin
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 3.6 | Low |
| Typical, some insulation, not air-sealed | 6.0 | Moderate |
| Older or poorly insulated, warm attic | 9.1 | Moderate |
Sealing and insulating a typical attic takes out about 2.5 days a winter here. It drops the risk from moderate to low. An older house with a warm attic should expect closer to 9.1 days.
Preventing ice dams on a Franklin 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.
Which to spend on first: air sealing or heat cable.
Franklin winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.3 | 8.5 | 2.6 |
| February | 4.2 | 7.6 | 2.1 |
| March | 2.2 | 1.7 | 0.3 |
| April | 0.1 | 0.0 | 0.0 |
| October | 0.1 | 0.0 | 0.0 |
| November | 0.2 | 0.3 | 0.0 |
| December | 3.8 | 4.2 | 1.0 |
Franklin next to nearby towns
Franklin ranks 70 of 88 Indiana cities here for ice-dam days, behind Plymouth at 15.9 days.
- Greenwood, IN 8 mi, 6.0 days
- Bargersville, IN 9 mi, 6.0 days
- Shelbyville, IN 15 mi, 4.0 days
- Beech Grove, IN 15 mi, 7.0 days
- Mooresville, IN 19 mi, 7.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Franklin Wwtp, 1.9 miles from Franklin. 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.