Ice dam risk in Hartford, WI
Ice dams in Hartford, WI: how often
26.7 dam days a winter
High risk. On an ordinary house in Hartford, conditions for an ice dam come on about 26.7 days in a normal winter, mostly in January and February.
Hartford averages 36 inches of snow a year and about 74 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 Hartford
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.1 | Moderate |
| Typical, some insulation, not air-sealed | 26.7 | High |
| Older or poorly insulated, warm attic | 46.2 | Severe |
Sealing and insulating a typical attic takes out about 15.6 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 46.2 days.
What to do about ice dams in Hartford
- 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.
Hartford winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 10.0 | 24.1 | 9.9 |
| February | 9.1 | 21.4 | 8.2 |
| March | 4.0 | 9.7 | 2.5 |
| April | 1.4 | 0.8 | 0.1 |
| May | 0.3 | 0.0 | 0.0 |
| October | 0.3 | 0.1 | 0.0 |
| November | 1.1 | 2.5 | 0.6 |
| December | 10.1 | 15.2 | 5.5 |
Hartford next to nearby towns
Hartford ranks 42 of 98 Wisconsin cities here for ice-dam days, behind Wausau at 41.6 days.
- Richfield, WI 9 mi, 24.6 days
- West Bend, WI 12 mi, 24.6 days
- Lisbon, WI 13 mi, 24.6 days
- Germantown, WI 14 mi, 24.6 days
- Sussex, WI 15 mi, 24.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Hartford Wwtp, 1.8 miles from Hartford. 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.