Ice dam risk in Hanover Park, IL
How often ice dams form in Hanover Park
19.1 dam days a winter
High risk. On an ordinary house in Hanover Park, conditions for an ice dam come on about 19.1 days in a normal winter, mostly in January and December.
Hanover Park averages 34 inches of snow a year and about 60 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 Hanover Park
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 10.3 | Moderate |
| Typical, some insulation, not air-sealed | 19.1 | High |
| Older or poorly insulated, warm attic | 30.1 | High |
Sealing and insulating a typical attic takes out about 8.8 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 30.1 days.
What to do about ice dams in Hanover Park
- 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.
Hanover Park winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 11.9 | 20.6 | 7.6 |
| February | 6.0 | 15.2 | 4.7 |
| March | 4.8 | 5.7 | 1.3 |
| April | 0.7 | 0.5 | 0.1 |
| October | 0.1 | 0.1 | 0.0 |
| November | 1.8 | 1.9 | 0.4 |
| December | 8.7 | 15.5 | 5.1 |
Hanover Park next to nearby towns
Hanover Park ranks 21 of 225 Illinois cities here for ice-dam days, behind Arlington Heights at 21.5 days.
- Bartlett, IL 2 mi, 19.1 days
- Roselle, IL 3 mi, 19.1 days
- Streamwood, IL 3 mi, 19.1 days
- Bloomingdale, IL 3 mi, 19.1 days
- Carol Stream, IL 4 mi, 19.1 days
Where these numbers come from
NOAA 1991–2020 climate normals from Streamwood, 3.5 miles from Hanover Park. 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.