Ice dam risk in Braintree Town, MA
How often ice dams form in Braintree Town
11.2 dam days a winter
Moderate risk. On an ordinary house in Braintree Town, conditions for an ice dam come on about 11.2 days in a normal winter, mostly in January and February.
Braintree Town averages 51 inches of snow a year and about 46 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 Braintree Town
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.6 | Moderate |
| Typical, some insulation, not air-sealed | 11.2 | Moderate |
| Older or poorly insulated, warm attic | 15.6 | High |
Sealing and insulating a typical attic takes out about 3.6 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 15.6 days.
What to do about ice dams in Braintree Town
- 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.
Braintree Town winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 14.8 | 14.8 | 4.3 |
| February | 14.5 | 13.4 | 3.6 |
| March | 10.3 | 9.3 | 1.6 |
| April | 1.7 | 0.6 | 0.0 |
| October | 0.1 | 0.1 | 0.0 |
| November | 0.7 | 0.5 | 0.1 |
| December | 8.8 | 7.5 | 1.6 |
Braintree Town next to nearby towns
Braintree Town ranks 46 of 58 Massachusetts cities here for ice-dam days, behind Pittsfield at 31.3 days.
- Weymouth Town, MA 3 mi, 11.2 days
- Randolph Town, MA 3 mi, 15.3 days
- Quincy, MA 4 mi, 11.2 days
- Brockton, MA 9 mi, 7.6 days
- Boston, MA 9 mi, 10.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Hingham, 4.8 miles from Braintree Town. 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.