Ice dam risk in Durango, CO
Ice dams in Durango, CO: how often
30.8 dam days a winter
High risk. On an ordinary house in Durango, conditions for an ice dam come on about 30.8 days in a normal winter, mostly in January and December.
Durango averages 64 inches of snow a year and about 124 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 Durango
| Attic | Dam days | Risk |
|---|---|---|
| Air-sealed and well insulated | 27.4 | High |
| Typical, some insulation, not air-sealed | 30.8 | High |
| Older or poorly insulated, warm attic | 35.0 | Severe |
Sealing and insulating a typical attic takes out about 3.4 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 35.0 days.
What to do about ice dams in Durango
- 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 61 kWh a winter in Durango, roughly $10 at 17 cents a kWh.
Which to spend on first: air sealing or heat cable.
Durango winter, month by month
| Month | Snow (in) | Days on ground | Dam days |
|---|---|---|---|
| January | 19.4 | 29.1 | 8.1 |
| February | 15.4 | 26.2 | 6.5 |
| March | 5.3 | 22.2 | 4.9 |
| April | 3.8 | 7.2 | 1.1 |
| May | 0.2 | 0.6 | 0.0 |
| October | 1.1 | 1.6 | 0.2 |
| November | 5.5 | 11.5 | 2.6 |
| December | 13.0 | 25.8 | 7.3 |
Durango next to nearby towns
Durango ranks 2 of 53 Colorado cities here for ice-dam days, behind Steamboat Springs at 51.0 days.
- Farmington, NM 39 mi, 1.6 days
- Montrose, CO 83 mi, 10.1 days
- Gallup, NM 130 mi, 6.1 days
- Grand Junction, CO 132 mi, 6.9 days
- Española, NM 133 mi, 1.8 days
Where these numbers come from
NOAA 1991–2020 climate normals from Durango, 2.1 miles from Durango. 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 Durango, 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.