Ice dam risk in Clinton, IA
Ice dams in Clinton, IA: how often
16.6 dam days a winter
High risk. On an ordinary house in Clinton, conditions for an ice dam come on about 16.6 days in a normal winter, mostly in January and February.
Clinton averages 32 inches of snow a year and about 51 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 Clinton
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.9 | Moderate |
| Typical, some insulation, not air-sealed | 16.6 | High |
| Older or poorly insulated, warm attic | 27.6 | 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 27.6 days.
What to do about ice dams in Clinton
- 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.
Clinton winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 9.2 | 20.2 | 7.6 |
| February | 7.5 | 13.8 | 4.5 |
| March | 3.9 | 4.2 | 0.8 |
| April | 0.8 | 0.2 | 0.0 |
| October | 0.3 | 0.1 | 0.0 |
| November | 2.3 | 1.7 | 0.3 |
| December | 7.9 | 11.1 | 3.5 |
Clinton next to nearby towns
Clinton ranks 23 of 41 Iowa cities here for ice-dam days, behind Mason City at 28.7 days.
- Bettendorf, IA 23 mi, 15.9 days
- East Moline, IL 24 mi, 15.9 days
- Davenport, IA 27 mi, 14.0 days
- Moline, IL 28 mi, 15.9 days
- Sterling, IL 28 mi, 16.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Clinton #1, 3.5 miles from Clinton. 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.