Ice dam risk in Gardner, MA
Will your roof get ice dams in Gardner, MA?
29.3 dam days a winter
High risk. On an ordinary house in Gardner, conditions for an ice dam come on about 29.3 days in a normal winter, mostly in January and February.
Gardner averages 75 inches of snow a year and about 91 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 Gardner
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 15.3 | High |
| Typical, some insulation, not air-sealed | 29.3 | High |
| Older or poorly insulated, warm attic | 46.7 | Severe |
Sealing and insulating a typical attic takes out about 14.0 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 46.7 days.
What to do about ice dams in Gardner
- 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.
- Heat cable is worth pricing here even on a sealed house, along the eave and in the gutters and downspouts it drains into.
Running 60 feet of 5 W/ft cable whenever snow lies below freezing would use about 251 kWh a winter in Gardner, roughly $43 at 17 cents a kWh.
Which to spend on first: air sealing or heat cable.
Gardner winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 16.9 | 24.3 | 9.3 |
| February | 18.9 | 23.5 | 8.4 |
| March | 16.4 | 20.0 | 5.1 |
| April | 4.0 | 4.0 | 0.5 |
| May | 0.1 | 0.0 | 0.0 |
| October | 0.3 | 0.1 | 0.0 |
| November | 3.0 | 2.7 | 0.5 |
| December | 15.6 | 16.7 | 5.4 |
Gardner next to nearby towns
Gardner ranks 5 of 58 Massachusetts cities here for ice-dam days, behind Pittsfield at 31.3 days.
- Fitchburg, MA 9 mi, 29.3 days
- Leominster, MA 12 mi, 29.3 days
- Worcester, MA 24 mi, 22.1 days
- Marlborough, MA 28 mi, 13.0 days
- Nashua, NH 28 mi, 24.1 days
Where these numbers come from
NOAA 1991–2020 climate normals from Ashburnham, 4.4 miles from Gardner. 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.