Ice dam risk in Dickinson, ND
Ice dams in Dickinson, ND: how often
23.8 dam days a winter
High risk. On an ordinary house in Dickinson, conditions for an ice dam come on about 23.8 days in a normal winter, mostly in January and February.
Dickinson averages 35 inches of snow a year and about 69 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 Dickinson
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.3 | Moderate |
| Typical, some insulation, not air-sealed | 23.8 | High |
| Older or poorly insulated, warm attic | 39.5 | Severe |
Sealing and insulating a typical attic takes out about 12.5 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 39.5 days.
What to do about ice dams in Dickinson
- 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.
Dickinson winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 5.5 | 19.6 | 7.6 |
| February | 5.8 | 15.3 | 6.0 |
| March | 6.4 | 10.3 | 3.1 |
| April | 3.4 | 3.8 | 0.7 |
| May | 0.9 | 0.4 | 0.0 |
| June | 0.1 | 0.0 | 0.0 |
| September | 0.1 | 0.1 | 0.0 |
| October | 2.6 | 2.3 | 0.3 |
| November | 3.7 | 4.8 | 1.4 |
| December | 6.6 | 12.1 | 4.7 |
Dickinson next to nearby towns
Dickinson ranks 9 of 9 North Dakota cities here for ice-dam days, behind Jamestown at 45.7 days.
- Mandan, ND 90 mi, 33.8 days
- Bismarck, ND 96 mi, 33.8 days
- Williston, ND 98 mi, 36.3 days
- Minot, ND 117 mi, 42.0 days
- Spearfish, SD 173 mi, 17.4 days
Where these numbers come from
NOAA 1991–2020 climate normals from Taylor 7 NNW, 16.8 miles from Dickinson. 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.