Ice dam risk in Farmington, UT
How often ice dams form in Farmington
20.4 dam days a winter
High risk. On an ordinary house in Farmington, conditions for an ice dam come on about 20.4 days in a normal winter, mostly in January and December.
Farmington averages 50 inches of snow a year and about 89 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 Farmington
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 15.5 | High |
| Typical, some insulation, not air-sealed | 20.4 | High |
| Older or poorly insulated, warm attic | 26.6 | High |
Sealing and insulating a typical attic takes out about 4.9 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 26.6 days.
What to do about ice dams in Farmington
- 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 89 kWh a winter in Farmington, roughly $15 at 17 cents a kWh.
Which to spend on first: air sealing or heat cable.
Farmington winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 16.0 | 25.2 | 7.3 |
| February | 11.5 | 20.0 | 4.5 |
| March | 4.2 | 9.6 | 1.3 |
| April | 0.9 | 2.7 | 0.1 |
| October | 0.4 | 1.0 | 0.0 |
| November | 6.6 | 7.6 | 1.2 |
| December | 10.0 | 23.0 | 6.0 |
Farmington next to nearby towns
Farmington ranks 12 of 67 Utah cities here for ice-dam days, behind Ogden at 37.2 days.
- Kaysville, UT 4 mi, 6.1 days
- Centerville, UT 4 mi, 20.7 days
- Layton, UT 7 mi, 6.7 days
- Woods Cross, UT 8 mi, 16.0 days
- Bountiful, UT 8 mi, 20.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Farmington 3 NW, 2.8 miles from Farmington. 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.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.