Ice dam risk in Lancaster, OH
Ice dams in Lancaster, OH: how often
5.2 dam days a winter
Moderate risk. On an ordinary house in Lancaster, conditions for an ice dam come on about 5.2 days in a normal winter, mostly in January and February.
Lancaster averages 15 inches of snow a year and about 21 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 Lancaster
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 3.1 | Low |
| Typical, some insulation, not air-sealed | 5.2 | Moderate |
| Older or poorly insulated, warm attic | 8.0 | Moderate |
Sealing and insulating a typical attic takes out about 2.2 days a winter here. It drops the risk from moderate to low.
Preventing ice dams on a Lancaster 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.
Which to spend on first: air sealing or heat cable.
Lancaster winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 6.7 | 9.0 | 2.6 |
| February | 4.6 | 5.9 | 1.5 |
| March | 1.5 | 1.7 | 0.3 |
| April | 0.2 | 0.1 | 0.0 |
| November | 0.4 | 0.6 | 0.1 |
| December | 2.0 | 3.5 | 0.8 |
Lancaster next to nearby towns
Lancaster ranks 168 of 176 Ohio cities here for ice-dam days, behind Euclid at 24.8 days.
- Pickerington, OH 14 mi, 6.7 days
- Canal Winchester, OH 14 mi, 6.7 days
- Reynoldsburg, OH 19 mi, 6.7 days
- Circleville, OH 19 mi, 5.2 days
- Pataskala, OH 21 mi, 6.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Circleville, 20.3 miles from Lancaster. 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.