Ice dam risk in Cottonwood Heights, UT
Will your roof get ice dams in Cottonwood Heights, UT?
16.2 dam days a winter
High risk. On an ordinary house in Cottonwood Heights, conditions for an ice dam come on about 16.2 days in a normal winter, mostly in January and December.
Cottonwood Heights averages 82 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 Cottonwood Heights
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 11.2 | Moderate |
| Typical, some insulation, not air-sealed | 16.2 | High |
| Older or poorly insulated, warm attic | 22.4 | High |
Sealing and insulating a typical attic takes out about 5.0 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 22.4 days.
Preventing ice dams on a Cottonwood Heights 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.
Which to spend on first: air sealing or heat cable.
Cottonwood Heights winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 17.0 | 21.9 | 6.0 |
| February | 18.4 | 18.2 | 3.7 |
| March | 7.6 | 5.0 | 0.5 |
| April | 5.6 | 0.6 | 0.0 |
| May | 0.3 | 0.0 | 0.0 |
| October | 1.5 | 0.2 | 0.0 |
| November | 8.2 | 5.0 | 0.7 |
| December | 23.3 | 18.3 | 5.2 |
Cottonwood Heights next to nearby towns
Cottonwood Heights ranks 23 of 67 Utah cities here for ice-dam days, behind Ogden at 37.2 days.
- Holladay, UT 3 mi, 10.7 days
- Sandy, UT 3 mi, 16.2 days
- Midvale, UT 4 mi, 10.7 days
- Murray, UT 5 mi, 10.7 days
- Millcreek, UT 5 mi, 10.7 days
Where these numbers come from
NOAA 1991–2020 climate normals from Cottonwood Weir, 1.7 miles from Cottonwood Heights. 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.
- The nearest weather station sits at a noticeably different elevation from Cottonwood Heights, so the snow figures may run high or low for the town itself.
- Snow-on-the-ground counts come from a second, nearby station, because the closest one does not record them.