How to actually stop ice dams in Oakland County.
Every February, the calls roll in: "There's a wall of ice on my roof and water's coming through the ceiling." If you've lived in Bloomfield Hills, Birmingham, Rochester, or pretty much anywhere in Oakland County for more than a couple winters, you've either had an ice dam or you know someone who has.
What an ice dam actually is.
An ice dam is a ridge of ice that builds up at the eave of your roof — the lowest, coldest edge that overhangs the wall. Once the ridge gets tall enough, snowmelt running down the warmer upper part of the roof hits the ice dam, has nowhere to go, and starts pooling. Then it works backwards under the shingles. Then it drips down through the soffit, into the wall, and onto your dining room ceiling.
Ice dams aren't really a roof problem. They're an attic problem.
This is the core thing to get. Ice dams happen because the upper part of your roof is warmer than the eave. Snow melts on the warm part, runs down to the eave (which is at outdoor air temperature), and refreezes. The bigger the temperature differential, the worse the dam.
Why is the upper roof warmer than the eave? Two reasons:
- Heat is escaping into the attic. Either because attic insulation is undersized, because warm air is leaking through can lights and bath fans, or because the duct work is uninsulated.
- The attic isn't venting properly. Cold outside air should be entering at the soffit and exiting at the ridge. If the soffits are clogged, painted over, or undersized, the air doesn't move — and the heat builds up.
What does and doesn't work to stop ice dams.
Doesn't really work:
- Heat cables. They melt a channel through the dam. They don't stop the dam from forming.
- Salt or calcium chloride socks. They corrode flashing and stain shingles.
- Roof rakes. Help in an emergency but don't stop the underlying cause.
Actually works:
- Air-seal the attic floor. Find every penetration where warm air leaks into the attic — can lights, attic hatch, plumbing chases. Seal them.
- Add insulation to R-49 or better. Michigan code is R-49 (about 14" of blown-in). Many older Oakland County homes are at R-19 or R-30.
- Verify continuous soffit intake. Look at your soffits. Are the vents clear?
- Install ice and water shield at the next reroof. Michigan code requires it 24" past the warm wall. We install it 6 feet up from every eave.
How to tell if it's a roof problem or an attic problem.
Most ice dams are attic problems. But there are cases where the roof itself is contributing — valleys icing repeatedly, dams over unheated sections, skylights leaking on thaw. If you can't tell, we'll come look. Free, no obligation.
Quick action checklist for this winter.
- Walk the attic on a cold day. Can you feel air movement at the soffits?
- Look at the underside of the roof deck. Frost on the deck = warm air leaking up.
- Check insulation depth. Less than 12 inches? You're under-insulated.
- Watch the roof after the first heavy snow. Patchy melt = attic heat loss.
- If you've had ice dams two winters in a row, the next reroof is the time to fix it for good.