Ice dam risk in Defiance, OH
Will your roof get ice dams in Defiance, OH?
11.7 dam days a winter
Moderate risk. On an ordinary house in Defiance, conditions for an ice dam come on about 11.7 days in a normal winter, mostly in January and February.
Defiance averages 24 inches of snow a year and about 38 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 Defiance
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 5.8 | Moderate |
| Typical, some insulation, not air-sealed | 11.7 | Moderate |
| Older or poorly insulated, warm attic | 19.0 | High |
Sealing and insulating a typical attic takes out about 5.9 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 19.0 days.
Preventing ice dams on a Defiance 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.
Defiance winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 8.7 | 14.2 | 5.0 |
| February | 8.0 | 11.0 | 3.5 |
| March | 2.6 | 3.5 | 0.7 |
| April | 0.2 | 0.1 | 0.0 |
| November | 0.9 | 1.5 | 0.2 |
| December | 3.8 | 7.6 | 2.2 |
Defiance next to nearby towns
Defiance ranks 83 of 176 Ohio cities here for ice-dam days, behind Euclid at 24.8 days.
- Van Wert, OH 31 mi, 6.0 days
- Auburn, IN 36 mi, 12.0 days
- New Haven, IN 37 mi, 11.4 days
- Bowling Green, OH 38 mi, 11.4 days
- Lima, OH 40 mi, 6.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Defiance, 1.0 miles from Defiance. 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.