Ice dam risk in Marinette, WI
How often ice dams form in Marinette
31.3 dam days a winter
High risk. On an ordinary house in Marinette, conditions for an ice dam come on about 31.3 days in a normal winter, mostly in January and February.
Marinette averages 44 inches of snow a year and about 87 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 Marinette
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 13.0 | Moderate |
| Typical, some insulation, not air-sealed | 31.3 | High |
| Older or poorly insulated, warm attic | 54.2 | Severe |
Sealing and insulating a typical attic takes out about 18.3 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 54.2 days.
What to do about ice dams in Marinette
- 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.
Marinette winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 11.7 | 25.4 | 10.8 |
| February | 11.1 | 25.2 | 9.8 |
| March | 7.6 | 15.8 | 4.3 |
| April | 3.4 | 2.9 | 0.3 |
| October | 0.1 | 0.0 | 0.0 |
| November | 1.9 | 2.5 | 0.5 |
| December | 8.0 | 15.5 | 5.6 |
Marinette next to nearby towns
Marinette ranks 17 of 98 Wisconsin cities here for ice-dam days, behind Wausau at 41.6 days.
- Suamico, WI 37 mi, 29.3 days
- Howard, WI 42 mi, 29.3 days
- Green Bay, WI 43 mi, 29.3 days
- Bellevue, WI 46 mi, 29.3 days
- Allouez, WI 47 mi, 29.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Marinette, 0.9 miles from Marinette. 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.