Ice dam risk in Canandaigua, NY
How often ice dams form in Canandaigua
24.0 dam days a winter
High risk. On an ordinary house in Canandaigua, conditions for an ice dam come on about 24.0 days in a normal winter, mostly in January and February.
Canandaigua averages 57 inches of snow a year and about 77 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 Canandaigua
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.8 | Moderate |
| Typical, some insulation, not air-sealed | 24.0 | High |
| Older or poorly insulated, warm attic | 39.3 | Severe |
Sealing and insulating a typical attic takes out about 12.2 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 39.3 days.
What to do about ice dams in Canandaigua
- 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.
Canandaigua winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 13.5 | 21.2 | 7.7 |
| February | 13.3 | 21.0 | 7.3 |
| March | 12.8 | 14.5 | 3.7 |
| April | 1.8 | 1.4 | 0.1 |
| October | 0.1 | 0.1 | 0.0 |
| November | 4.7 | 4.4 | 0.7 |
| December | 10.4 | 14.8 | 4.4 |
Canandaigua next to nearby towns
Canandaigua ranks 23 of 90 New York cities here for ice-dam days, behind Utica at 46.1 days.
- Geneva, NY 15 mi, 24.0 days
- Rochester, NY 26 mi, 21.2 days
- Auburn, NY 36 mi, 26.1 days
- Batavia, NY 46 mi, 19.5 days
- Ithaca, NY 50 mi, 22.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Geneva Rsch Farm, 12.7 miles from Canandaigua. 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.