Ice dam risk in Frankfort, IL
Ice dams in Frankfort, IL: how often
14.7 dam days a winter
Moderate risk. On an ordinary house in Frankfort, conditions for an ice dam come on about 14.7 days in a normal winter, mostly in January and February.
Frankfort averages 28 inches of snow a year and about 46 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 Frankfort
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.1 | Moderate |
| Typical, some insulation, not air-sealed | 14.7 | Moderate |
| Older or poorly insulated, warm attic | 24.2 | High |
Sealing and insulating a typical attic takes out about 7.6 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 24.2 days.
What to do about ice dams in Frankfort
- 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.
Frankfort winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 10.2 | 18.3 | 6.8 |
| February | 7.5 | 12.7 | 4.0 |
| March | 4.9 | 5.1 | 1.0 |
| April | 0.5 | 0.2 | 0.0 |
| October | 0.2 | 0.1 | 0.0 |
| November | 0.9 | 1.2 | 0.2 |
| December | 4.0 | 8.8 | 2.7 |
Frankfort next to nearby towns
Frankfort ranks 68 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Mokena, IL 2 mi, 14.7 days
- New Lenox, IL 5 mi, 8.8 days
- Tinley Park, IL 5 mi, 14.7 days
- Matteson, IL 6 mi, 14.7 days
- Richton Park, IL 7 mi, 14.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Park Forest, 9.9 miles from Frankfort. 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.