What Causes Ice Dams on Michigan Roofs, and How to Stop Them
Short answer: ice dams form when heat from the house warms the roof, snow melts higher up, and the water refreezes at the cold edge of the roof. The fix is mostly in the attic: seal the air leaks, add insulation and make sure the roof is vented, plus an ice and water barrier at the eaves when the roof is replaced.
How an Ice Dam Forms
Warm air from the living space leaks into the attic and warms the roof deck. Snow on the upper part of the roof melts even when it is below freezing outside. The water runs down to the eaves, which hang past the warm house and stay cold, and freezes there. Day after day the ridge of ice grows, and water backs up behind it, under the shingles and into the ceiling and walls.
Signs You Have a Problem
- A thick ridge of ice along the edge of the roof or in the gutters.
- Large icicles, especially with water dripping behind them.
- Water stains or peeling paint on ceilings and walls near outside walls, or wet insulation in the attic.
- Snow melting in patches on the roof while the neighbors' roofs are still white.
What to Do When You Have One
- Pull the snow off the lower few feet of the roof with a roof rake, from the ground.
- Do not chip at the ice with a hammer, shovel or ice pick. It damages shingles and gutters.
- Do not climb on an icy roof. It is not worth the risk.
- If water is coming inside, catch it, move valuables and call a roofer to look at the damage once it is safe.
How to Stop Them for Good
- Seal the attic air leaks. Gaps around light fixtures, the attic hatch, plumbing and chimneys let warm air in.
- Add insulation so the heat stays in the house.
- Vent the roof. Soffit vents at the eaves and vents at the ridge keep the roof deck cold and even.
- Ice and water barrier at the eaves. When a roof is replaced, a self sealing membrane goes under the shingles along the edge, so water that backs up cannot get through. Building codes in cold climates call for it on new roofs.
- Keep gutters clear. Clogged gutters do not cause ice dams, but they make the ice build faster.
Need a Look?
If you had ice dams last winter or see stains near the edge of a ceiling, we can inspect the roof, show you photos and tell you whether it needs a repair, better venting or a new roof. Inspections and estimates are free. Call (734) 427-3981.
Questions
Do gutters cause ice dams?
No. Ice dams come from heat escaping into the attic and warming the roof. Clogged gutters can make ice build up faster, so keeping them clear still helps.
Are heat cables a good fix for ice dams?
They can keep a channel open in a problem spot, but they do not fix the cause. Sealing attic air leaks, insulation and roof venting are the long term fix.
Will homeowners insurance cover ice dam damage?
That depends on your policy, so check with your insurance company. We can give you inspection photos and a written estimate to send with a claim. We do not file or manage the claim.
Can ice dams damage a new roof?
A new roof with an ice and water barrier at the eaves is much better protected, but the cause is still the attic. Venting and insulation keep ice from forming in the first place.
Related: Roof replacement and roofing, Roof repairs, Seamless gutters