Ice dam risk in Waunakee, WI
Ice dams in Waunakee, WI: how often
26.5 dam days a winter
High risk. On an ordinary house in Waunakee, conditions for an ice dam come on about 26.5 days in a normal winter, mostly in January and February.
Waunakee averages 52 inches of snow a year and about 78 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 Waunakee
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.7 | Moderate |
| Typical, some insulation, not air-sealed | 26.5 | High |
| Older or poorly insulated, warm attic | 44.9 | Severe |
Sealing and insulating a typical attic takes out about 14.7 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 44.9 days.
What to do about ice dams in Waunakee
- 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.
Waunakee winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 13.7 | 24.2 | 9.7 |
| February | 12.8 | 22.4 | 8.2 |
| March | 7.0 | 10.1 | 2.3 |
| April | 2.6 | 1.3 | 0.1 |
| May | 0.1 | 0.0 | 0.0 |
| October | 0.6 | 0.2 | 0.0 |
| November | 3.0 | 3.3 | 0.7 |
| December | 12.0 | 16.0 | 5.5 |
Waunakee next to nearby towns
Waunakee ranks 45 of 98 Wisconsin cities here for ice-dam days, behind Wausau at 41.6 days.
- DeForest, WI 6 mi, 28.8 days
- Middleton, WI 6 mi, 22.2 days
- Madison, WI 7 mi, 22.2 days
- Windsor, WI 9 mi, 28.8 days
- Sun Prairie, WI 10 mi, 26.5 days
Where these numbers come from
NOAA 1991–2020 climate normals from Madison Dane County Regional Airport, 5.8 miles from Waunakee. 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.