Ice dam risk in Grand Forks, ND
How often ice dams form in Grand Forks
44.3 dam days a winter
Severe risk. On an ordinary house in Grand Forks, conditions for an ice dam come on about 44.3 days in a normal winter, mostly in January and February.
Grand Forks averages 49 inches of snow a year and about 108 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 Grand Forks
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 14.6 | Moderate |
| Typical, some insulation, not air-sealed | 44.3 | Severe |
| Older or poorly insulated, warm attic | 81.4 | Severe |
Sealing and insulating a typical attic takes out about 29.7 days a winter here. It drops the risk from severe to moderate. An older house with a warm attic should expect closer to 81.4 days.
What to do about ice dams in Grand Forks
- 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.
Grand Forks winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 9.5 | 28.9 | 13.5 |
| February | 8.2 | 24.8 | 10.9 |
| March | 7.8 | 17.9 | 6.0 |
| April | 3.0 | 2.9 | 0.5 |
| May | 0.1 | 0.0 | 0.0 |
| October | 1.5 | 0.9 | 0.1 |
| November | 5.1 | 9.5 | 3.1 |
| December | 13.5 | 23.1 | 10.3 |
Grand Forks next to nearby towns
Grand Forks ranks 2 of 9 North Dakota cities here for ice-dam days, behind Jamestown at 45.7 days.
- Fargo, ND 74 mi, 43.6 days
- West Fargo, ND 74 mi, 41.7 days
- Moorhead, MN 75 mi, 43.6 days
- Detroit Lakes, MN 96 mi, 46.7 days
- Jamestown, ND 103 mi, 45.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Grand Forks Univ (Nws), 0.5 miles from Grand Forks. 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.