Ice dam risk in Jackson, MI
Ice dams in Jackson, MI: how often
18.6 dam days a winter
High risk. On an ordinary house in Jackson, conditions for an ice dam come on about 18.6 days in a normal winter, mostly in January and February.
Jackson averages 33 inches of snow a year and about 56 days with snow on the ground. Most of it comes and goes within a few days. 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 Jackson
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 8.6 | Moderate |
| Typical, some insulation, not air-sealed | 18.6 | High |
| Older or poorly insulated, warm attic | 31.0 | High |
Sealing and insulating a typical attic takes out about 10.0 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 31.0 days.
What to do about ice dams in Jackson
- 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.
Jackson winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 10.9 | 20.2 | 7.7 |
| February | 8.6 | 15.7 | 5.6 |
| March | 4.7 | 6.6 | 1.5 |
| April | 0.9 | 0.7 | 0.1 |
| November | 1.8 | 1.8 | 0.3 |
| December | 6.0 | 11.2 | 3.5 |
Jackson next to nearby towns
Jackson ranks 43 of 90 Michigan cities here for ice-dam days, behind Sault Ste. Marie at 48.8 days.
- Adrian, MI 30 mi, 14.9 days
- Lansing, MI 33 mi, 21.6 days
- Ann Arbor, MI 35 mi, 20.5 days
- East Lansing, MI 35 mi, 21.3 days
- Coldwater, MI 37 mi, 17.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Chelsea, 20.8 miles from Jackson. 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.