Ice dam risk in Birmingham, MI
Will your roof get ice dams in Birmingham, MI?
19.6 dam days a winter
High risk. On an ordinary house in Birmingham, conditions for an ice dam come on about 19.6 days in a normal winter, mostly in January and February.
Birmingham averages 36 inches of snow a year and about 62 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 Birmingham
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 9.6 | Moderate |
| Typical, some insulation, not air-sealed | 19.6 | High |
| Older or poorly insulated, warm attic | 32.2 | 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 32.2 days.
Preventing ice dams on a Birmingham roof
- 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.
Birmingham winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 12.1 | 21.7 | 7.9 |
| February | 9.0 | 17.5 | 6.0 |
| March | 4.1 | 7.4 | 1.7 |
| April | 0.9 | 0.6 | 0.1 |
| October | 0.1 | 0.0 | 0.0 |
| November | 1.7 | 1.4 | 0.2 |
| December | 8.1 | 12.9 | 3.7 |
Birmingham next to nearby towns
Birmingham ranks 35 of 90 Michigan cities here for ice-dam days, behind Sault Ste. Marie at 48.8 days.
- Beverly Hills, MI 2 mi, 18.1 days
- Clawson, MI 3 mi, 19.6 days
- Berkley, MI 4 mi, 18.1 days
- Royal Oak, MI 4 mi, 19.6 days
- Troy, MI 5 mi, 19.6 days
Where these numbers come from
NOAA 1991–2020 climate normals from Pontiac Wwtp, 6.8 miles from Birmingham. 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.