Ice dam risk in Eau Claire, WI
Ice dams in Eau Claire, WI: how often
33.4 dam days a winter
High risk. On an ordinary house in Eau Claire, conditions for an ice dam come on about 33.4 days in a normal winter, mostly in February and January.
Eau Claire averages 54 inches of snow a year and about 95 days with snow on the ground. Snow that lies that long is what turns a little attic heat into a ridge of ice at the eave. 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 Eau Claire
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 13.4 | Moderate |
| Typical, some insulation, not air-sealed | 33.4 | High |
| Older or poorly insulated, warm attic | 58.5 | Severe |
Sealing and insulating a typical attic takes out about 20.0 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 58.5 days.
Preventing ice dams on a Eau Claire 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.
Eau Claire winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 10.0 | 24.5 | 10.3 |
| February | 13.5 | 25.4 | 10.1 |
| March | 8.3 | 17.5 | 4.2 |
| April | 4.5 | 3.0 | 0.3 |
| May | 0.5 | 0.1 | 0.0 |
| October | 0.8 | 0.1 | 0.0 |
| November | 3.3 | 3.9 | 0.9 |
| December | 13.1 | 20.7 | 7.6 |
Eau Claire next to nearby towns
Eau Claire ranks 12 of 98 Wisconsin cities here for ice-dam days, behind Wausau at 41.6 days.
- Chippewa Falls, WI 10 mi, 36.1 days
- Menomonie, WI 21 mi, 32.7 days
- Winona, MN 54 mi, 30.7 days
- River Falls, WI 55 mi, 38.8 days
- New Richmond, WI 56 mi, 38.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Eau Claire 3SW, 2.4 miles from Eau Claire. 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.