Ice dam risk in Ionia, MI
Ice dams in Ionia, MI: how often
26.5 dam days a winter
High risk. On an ordinary house in Ionia, conditions for an ice dam come on about 26.5 days in a normal winter, mostly in January and February.
Ionia averages 54 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 Ionia
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.9 | Moderate |
| Typical, some insulation, not air-sealed | 26.5 | High |
| Older or poorly insulated, warm attic | 44.6 | Severe |
Sealing and insulating a typical attic takes out about 14.5 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 44.6 days.
What to do about ice dams in Ionia
- 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.
Ionia winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 15.5 | 24.2 | 9.4 |
| February | 11.9 | 21.6 | 8.0 |
| March | 7.0 | 11.2 | 2.8 |
| April | 1.6 | 1.0 | 0.1 |
| October | 0.5 | 0.2 | 0.0 |
| November | 3.6 | 2.9 | 0.5 |
| December | 14.1 | 17.0 | 5.6 |
Ionia next to nearby towns
Ionia ranks 7 of 90 Michigan cities here for ice-dam days, behind Sault Ste. Marie at 48.8 days.
- Kentwood, MI 27 mi, 21.5 days
- East Grand Rapids, MI 27 mi, 22.4 days
- Grand Rapids, MI 29 mi, 22.4 days
- Lansing, MI 32 mi, 21.6 days
- Wyoming, MI 33 mi, 22.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Ionia 2SSW, 1.6 miles from Ionia. 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.