Ice dam risk in Smithfield, UT
Will your roof get ice dams in Smithfield, UT?
23.2 dam days a winter
High risk. On an ordinary house in Smithfield, conditions for an ice dam come on about 23.2 days in a normal winter, mostly in January and December.
Smithfield averages 62 inches of snow a year and about 76 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 Smithfield
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 13.1 | Moderate |
| Typical, some insulation, not air-sealed | 23.2 | High |
| Older or poorly insulated, warm attic | 35.9 | Severe |
Sealing and insulating a typical attic takes out about 10.2 days a winter here. It drops the risk from high to moderate. An older house with a warm attic should expect closer to 35.9 days.
Preventing ice dams on a Smithfield 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.
Smithfield winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 12.9 | 23.8 | 8.3 |
| February | 12.7 | 19.3 | 5.6 |
| March | 8.9 | 6.4 | 1.2 |
| April | 4.0 | 0.6 | 0.1 |
| May | 0.5 | 0.0 | 0.0 |
| October | 1.3 | 0.3 | 0.0 |
| November | 6.6 | 4.7 | 1.0 |
| December | 15.4 | 20.4 | 7.0 |
Smithfield next to nearby towns
Smithfield ranks 7 of 67 Utah cities here for ice-dam days, behind Ogden at 37.2 days.
- North Logan, UT 4 mi, 23.3 days
- Logan, UT 7 mi, 23.3 days
- Hyrum, UT 14 mi, 24.8 days
- Tremonton, UT 20 mi, 15.7 days
- Brigham City, UT 26 mi, 14.3 days
Where these numbers come from
NOAA 1991–2020 climate normals from Richmond, 5.0 miles from Smithfield. 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.