Ice dam risk in Mount Pleasant, MI
Ice dams in Mount Pleasant, MI: how often
24.7 dam days a winter
High risk. On an ordinary house in Mount Pleasant, conditions for an ice dam come on about 24.7 days in a normal winter, mostly in January and February.
Mount Pleasant averages 39 inches of snow a year and about 72 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 Mount Pleasant
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.7 | Moderate |
| Typical, some insulation, not air-sealed | 24.7 | High |
| Older or poorly insulated, warm attic | 41.0 | Severe |
Sealing and insulating a typical attic takes out about 13.0 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 41.0 days.
What to do about ice dams in Mount Pleasant
- 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.
Mount Pleasant winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 10.7 | 23.3 | 9.3 |
| February | 9.9 | 20.7 | 7.6 |
| March | 5.4 | 10.7 | 2.7 |
| April | 2.1 | 1.1 | 0.1 |
| October | 0.3 | 0.1 | 0.0 |
| November | 2.7 | 2.3 | 0.4 |
| December | 8.2 | 14.1 | 4.5 |
Mount Pleasant next to nearby towns
Mount Pleasant ranks 8 of 90 Michigan cities here for ice-dam days, behind Sault Ste. Marie at 48.8 days.
- Midland, MI 27 mi, 21.6 days
- Saginaw, MI 43 mi, 21.6 days
- Bay City, MI 44 mi, 21.6 days
- Ionia, MI 45 mi, 26.5 days
- Owosso, MI 51 mi, 22.5 days
Where these numbers come from
NOAA 1991–2020 climate normals from Alma, 15.9 miles from Mount Pleasant. 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.