Ice dams are caused by heat escaping from your house into the attic, not by your gutters, your shingles, or the amount of snow. Warm air melts snow on the upper roof, the meltwater runs down to the cold overhang, refreezes into a ridge of ice, and everything behind that ridge backs up under your shingles. Utah Valley Foam is an independent insulation referral service covering Utah County, and this page explains the mechanism and what actually fixes it.
Why Utah County Roofs Are Prone to This
The valley produces close to ideal ice dam conditions every January. Snow sits on roofs for days rather than melting off. Daytime sun and freezing nights create the freeze and thaw cycle the dam needs to build. Homes on the benches, in Edgemont, Alpine, Cedar Hills, and up on Traverse Mountain, sit in colder air than the valley floor. North facing roof planes never get enough winter sun to clear, which is why the same side of the same house dams every single year.
Layered on top of that is housing stock. Most Utah County homes built before 2010 have attic insulation well short of the R-49 the code now calls for, and almost none of them were ever properly air sealed at the ceiling plane, the flat surface between your top floor and the attic above it.
What Is Actually Happening Above Your Ceiling
| What you see | What is causing it | What fixes it |
|---|---|---|
| Ice ridge along the gutter line | Attic air above freezing melting snow higher up the roof | Air seal the ceiling, then insulate to R-49 |
| Icicles hanging from the eaves | Meltwater refreezing as it reaches the unheated overhang | Same. Icicles are the symptom, not the problem |
| Water stains on upstairs ceilings | Backed up meltwater getting under the shingles | Stop the dam forming, not just the leak |
| One roof plane dams, the others do not | North facing slope never warms enough to shed snow | Air sealing matters even more on that side |
| Worse after a cold snap with sun | Freeze and thaw cycling is what builds the dam | Nothing weather related. Fix the heat loss |
What Does Not Fix Ice Dams
Plenty of money gets spent in this valley every winter on things that treat the symptom:
- Heat cables. They melt a channel through the dam so water can escape. They do not stop the dam forming, they run on your electricity all winter, and they have a service life measured in a few seasons.
- Raking snow off the roof. Genuinely helps in the moment, and you have to do it after every storm, from a ladder, in winter.
- New gutters or gutter guards. The dam forms on the roof edge. Gutters are where you notice it.
- A new roof. Ice and water shield under the shingles limits the damage when water backs up. It does not stop the water backing up.
- Adding insulation without air sealing. This is the common one. Blowing more fiberglass over a leaky ceiling slows heat conduction while air keeps pouring through every wire hole and can light. Partial fix, and often a disappointing one.
What Does Fix Them
Keep the attic cold. That sounds backwards until you follow the mechanism: if no heat reaches the roof deck, the snow on it does not melt, and with nothing melting there is nothing to refreeze at the eave.
Two steps, in this order. First, seal every air leak in the ceiling plane: top plates, wire and pipe penetrations, can lights, the attic hatch, and bath fan housings. Air leakage does far more to warm a roof deck than conduction through insulation does. Second, bring the insulation up to R-49 or better, which is what Utah’s energy code calls for in climate zone 5.
Spray foam does both in one application, which is why it is our default answer here. The alternative approach is sealing the roof deck instead and bringing the attic inside the thermal envelope, which the code permits at R-26 in zones 5B and 6B under specific conditions. Both routes are broken down on our Utah insulation code requirements page and on the attic insulation page.
Ice Dam FAQ
What actually causes ice dams?
Heat escaping from the house into the attic. It warms the roof deck, snow on the upper roof melts, the water runs to the cold overhang beyond the heated part of the house, and refreezes there. That ridge of ice traps everything behind it.
Do heat cables stop ice dams?
No. They melt a drainage channel through a dam that still forms. They run on electricity all winter, need replacing every few seasons, and leave the underlying heat loss untouched. They are a way to live with the problem, not a fix.
Will more attic insulation stop ice dams?
Only partly, if you skip air sealing. Air leaking through wire holes, can lights, and top plates carries far more heat into an attic than conduction through insulation. Seal first, then insulate to R-49. Doing the second without the first is the most common disappointment we get called about.
Why does only one side of my roof get ice dams?
Almost always the north facing slope. It gets the least winter sun, so snow sits there instead of shedding, giving heat loss from below more time to do its work. Common on bench homes in Edgemont, Alpine, and Cedar Hills.
Can ice dams damage my house?
Yes. Backed up water gets under shingles and into the roof deck, wall cavities, and upstairs ceilings. Repeated seasons cause rot and mould in the assembly. Ceiling stains after a thaw are the sign it has already reached the inside.
If the same roof plane dams every winter, the fix is above the ceiling. Call (801) 691-7136 for a free assessment anywhere in Utah County.