Ice dam risk in Grantsville, UT
Will your roof get ice dams in Grantsville, UT?
11.6 dam days a winter
Moderate risk. On an ordinary house in Grantsville, conditions for an ice dam come on about 11.6 days in a normal winter, mostly in January and December.
Grantsville averages 33 inches of snow a year and about 41 days with snow on the ground. Most of it comes and goes within a few days. 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 Grantsville
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 7.7 | Moderate |
| Typical, some insulation, not air-sealed | 11.6 | Moderate |
| Older or poorly insulated, warm attic | 16.4 | High |
Sealing and insulating a typical attic takes out about 3.9 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 16.4 days.
What to do about ice dams in Grantsville
- 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.
Which to spend on first: air sealing or heat cable.
Grantsville winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 7.2 | 14.7 | 4.7 |
| February | 7.5 | 9.9 | 2.5 |
| March | 3.5 | 1.8 | 0.3 |
| April | 1.9 | 0.5 | 0.0 |
| October | 0.1 | 0.0 | 0.0 |
| November | 5.0 | 2.6 | 0.5 |
| December | 7.9 | 11.6 | 3.6 |
Grantsville next to nearby towns
Grantsville ranks 34 of 67 Utah cities here for ice-dam days, behind Ogden at 37.2 days.
- Tooele, UT 10 mi, 16.4 days
- Magna, UT 18 mi, 10.4 days
- Kearns, UT 24 mi, 11.0 days
- West Jordan, UT 25 mi, 10.7 days
- West Valley City, UT 25 mi, 11.0 days
Where these numbers come from
NOAA 1991–2020 climate normals from Grantsville 2W, 2.1 miles from Grantsville. 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.