Ice dam risk in Sartell, MN
How often ice dams form in Sartell
39.1 dam days a winter
Severe risk. On an ordinary house in Sartell, conditions for an ice dam come on about 39.1 days in a normal winter, mostly in January and February.
Sartell averages 57 inches of snow a year and about 106 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 Sartell
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 15.3 | High |
| Typical, some insulation, not air-sealed | 39.1 | Severe |
| Older or poorly insulated, warm attic | 68.8 | Severe |
Sealing and insulating a typical attic takes out about 23.8 days a winter here. It drops the risk from severe to high. An older house with a warm attic should expect closer to 68.8 days.
Preventing ice dams on a Sartell 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.
- 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 428 kWh a winter in Sartell, roughly $73 at 17 cents a kWh.
Which to spend on first: air sealing or heat cable.
Sartell winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 11.2 | 28.7 | 12.8 |
| February | 10.2 | 26.1 | 10.4 |
| March | 10.1 | 17.0 | 4.5 |
| April | 6.6 | 3.6 | 0.4 |
| May | 0.1 | 0.0 | 0.0 |
| October | 0.7 | 0.4 | 0.0 |
| November | 8.0 | 8.1 | 2.1 |
| December | 10.5 | 21.6 | 8.8 |
Sartell next to nearby towns
Sartell ranks 23 of 103 Minnesota cities here for ice-dam days, behind Hermantown at 52.9 days.
- Sauk Rapids, MN 3 mi, 38.6 days
- St. Cloud, MN 7 mi, 38.6 days
- Big Lake, MN 30 mi, 36.5 days
- Monticello, MN 30 mi, 36.4 days
- Buffalo, MN 35 mi, 36.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Collegeville St John'S, 9.1 miles from Sartell. 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.