Ice dam risk in Boone, IA
How often ice dams form in Boone
21.8 dam days a winter
High risk. On an ordinary house in Boone, conditions for an ice dam come on about 21.8 days in a normal winter, mostly in January and February.
Boone 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 Boone
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 10.2 | Moderate |
| Typical, some insulation, not air-sealed | 21.8 | High |
| Older or poorly insulated, warm attic | 36.3 | Severe |
Sealing and insulating a typical attic takes out about 11.6 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 36.3 days.
What to do about ice dams in Boone
- 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.
Boone winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 9.9 | 20.8 | 8.4 |
| February | 9.3 | 18.0 | 6.5 |
| March | 5.0 | 7.2 | 1.7 |
| April | 1.3 | 0.6 | 0.1 |
| October | 0.6 | 0.2 | 0.0 |
| November | 1.9 | 2.4 | 0.5 |
| December | 7.9 | 13.1 | 4.6 |
Boone next to nearby towns
Boone ranks 10 of 41 Iowa cities here for ice-dam days, behind Mason City at 28.7 days.
- Ames, IA 13 mi, 19.3 days
- Johnston, IA 26 mi, 17.8 days
- Grimes, IA 26 mi, 17.8 days
- Ankeny, IA 26 mi, 17.4 days
- Urbandale, IA 29 mi, 17.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Boone, 1.1 miles from Boone. 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.