Ice dam risk in Truckee, CA
Ice dams in Truckee, CA: how often
36.3 dam days a winter
Severe risk. On an ordinary house in Truckee, conditions for an ice dam come on about 36.3 days in a normal winter, mostly in January and March.
Truckee averages 207 inches of snow a year and about 144 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 Truckee
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 32.2 | High |
| Typical, some insulation, not air-sealed | 36.3 | Severe |
| Older or poorly insulated, warm attic | 41.5 | Severe |
Sealing and insulating a typical attic takes out about 4.1 days a winter here. It drops the risk from severe to high. An older house with a warm attic should expect closer to 41.5 days.
What to do about ice dams in Truckee
- 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 74 kWh a winter in Truckee, roughly $13 at 17 cents a kWh.
Which to spend on first: air sealing or heat cable.
Truckee winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 43.6 | 30.6 | 8.5 |
| February | 47.9 | 26.9 | 7.0 |
| March | 32.2 | 29.1 | 7.0 |
| April | 18.5 | 15.2 | 3.4 |
| May | 4.1 | 2.8 | 0.3 |
| June | 0.9 | 0.3 | 0.0 |
| September | 0.5 | 0.2 | 0.0 |
| October | 2.8 | 1.9 | 0.4 |
| November | 11.9 | 10.3 | 2.5 |
| December | 44.2 | 26.5 | 7.2 |
Truckee next to nearby towns
Truckee ranks 1 of 376 California cities here for ice-dam days, the worst in the state.
- Reno, NV 23 mi, 3.1 days
- Carson, NV 28 mi, 1.9 days
- Sparks, NV 30 mi, 1.3 days
- South Lake Tahoe, CA 31 mi, 2.1 days
- Grass Valley, CA 47 mi, 0.2 days
Where these numbers come from
NOAA 1991–2020 climate normals from Truckee Rs, 1.6 miles from Truckee. 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.