Ice dam risk in South Bend, IN
Ice dams in South Bend, IN: how often
15.8 dam days a winter
High risk. On an ordinary house in South Bend, conditions for an ice dam come on about 15.8 days in a normal winter, mostly in January and February.
South Bend averages 65 inches of snow a year and about 52 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 South Bend
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.6 | Moderate |
| Typical, some insulation, not air-sealed | 15.8 | High |
| Older or poorly insulated, warm attic | 26.1 | High |
Sealing and insulating a typical attic takes out about 8.2 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 26.1 days.
Preventing ice dams on a South Bend 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.
- At the next reroof, ask for ice-and-water membrane under the shingles from the eave to at least 24 inches inside the wall line. It does not stop a dam; it stops the leak when one forms.
Which to spend on first: air sealing or heat cable.
South Bend winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 21.6 | 19.6 | 7.0 |
| February | 16.1 | 13.8 | 4.4 |
| March | 6.8 | 4.9 | 1.0 |
| April | 1.0 | 0.3 | 0.0 |
| October | 0.2 | 0.1 | 0.0 |
| November | 5.1 | 2.8 | 0.4 |
| December | 13.7 | 10.4 | 3.0 |
South Bend next to nearby towns
South Bend ranks 2 of 88 Indiana cities here for ice-dam days, behind Plymouth at 15.9 days.
- Mishawaka, IN 5 mi, 15.8 days
- Niles, MI 11 mi, 16.7 days
- Elkhart, IN 16 mi, 14.8 days
- Plymouth, IN 23 mi, 15.9 days
- La Porte, IN 23 mi, 15.5 days
Where these numbers come from
NOAA 1991–2020 climate normals from S Bend Airport, 3.2 miles from South Bend. 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.