Ice dam risk in Galesburg, IL
How often ice dams form in Galesburg
13.8 dam days a winter
Moderate risk. On an ordinary house in Galesburg, conditions for an ice dam come on about 13.8 days in a normal winter, mostly in January and February.
Galesburg averages 26 inches of snow a year and about 42 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 Galesburg
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 6.4 | Moderate |
| Typical, some insulation, not air-sealed | 13.8 | Moderate |
| Older or poorly insulated, warm attic | 22.9 | High |
Sealing and insulating a typical attic takes out about 7.3 days a winter here. It does not move the risk band, but it shortens every dam. An older house with a warm attic should expect closer to 22.9 days.
Preventing ice dams on a Galesburg 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.
Which to spend on first: air sealing or heat cable.
Galesburg winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 9.0 | 17.7 | 6.6 |
| February | 6.6 | 12.8 | 4.1 |
| March | 2.3 | 3.3 | 0.6 |
| April | 0.4 | 0.3 | 0.0 |
| November | 1.7 | 1.0 | 0.2 |
| December | 5.9 | 7.1 | 2.2 |
Galesburg next to nearby towns
Galesburg ranks 84 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Kewanee, IL 31 mi, 14.1 days
- Canton, IL 32 mi, 10.4 days
- Macomb, IL 37 mi, 10.6 days
- Moline, IL 37 mi, 15.9 days
- Rock Island, IL 37 mi, 14.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Galesburg, 0.5 miles from Galesburg. 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.