Ice dam risk in Crawfordsville, IN
How often ice dams form in Crawfordsville
8.5 dam days a winter
Moderate risk. On an ordinary house in Crawfordsville, conditions for an ice dam come on about 8.5 days in a normal winter, mostly in January and February.
Crawfordsville averages 22 inches of snow a year and about 28 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 Crawfordsville
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 4.5 | Low |
| Typical, some insulation, not air-sealed | 8.5 | Moderate |
| Older or poorly insulated, warm attic | 13.4 | Moderate |
Sealing and insulating a typical attic takes out about 3.9 days a winter here. It drops the risk from moderate to low. An older house with a warm attic should expect closer to 13.4 days.
Preventing ice dams on a Crawfordsville 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.
Crawfordsville winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 7.4 | 10.4 | 3.6 |
| February | 5.7 | 8.6 | 2.7 |
| March | 3.1 | 2.0 | 0.4 |
| April | 0.3 | 0.1 | 0.0 |
| November | 1.0 | 0.8 | 0.1 |
| December | 4.2 | 5.8 | 1.7 |
Crawfordsville next to nearby towns
Crawfordsville ranks 46 of 88 Indiana cities here for ice-dam days, behind Plymouth at 15.9 days.
- Lebanon, IN 23 mi, 7.6 days
- Lafayette, IN 25 mi, 9.9 days
- Frankfort, IN 25 mi, 7.9 days
- West Lafayette, IN 28 mi, 9.7 days
- Whitestown, IN 28 mi, 7.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Crawfordsville 6 SE, 5.8 miles from Crawfordsville. 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.