Why the Same Three Houses on Your Street Get Ice Dams

The Question Nobody Asks

Every January in the older parts of Davenport, Moline and Rock Island the same handful of houses on a block grow a ridge of ice along the gutter line and hang icicles to the porch rail. The house next door, in the same snow, under the same sky, stays clean.

That difference is not luck and it is not the roof. It is what is happening in the attic.

Where Your Heat Is Going

An ice dam needs a roof deck warm enough to melt snow while the eave stays below freezing. The only thing that can warm that deck from underneath is heat you paid for, leaving the house.

• Recessed light fixtures cut into an insulated ceiling, each one a hole
• The attic hatch, usually a thin panel with no weather seal
• Bathroom and kitchen fans venting into the attic instead of outside
• Gaps around a chimney chase or a plumbing stack
• Top plates of interior walls, open into the attic above
• Old insulation that has settled, compressed or been walked flat

Every one of those is on your gas bill already. The ice is just the visible version of it.

Why the Roof Is Not the Fix

People call a roofer about an ice dam, which is reasonable because the roof is where it shows and where the damage happens. A roofer can steam it off safely and can make the eaves far more resistant with ice and water shield at the next replacement.

Neither of those stops it happening. The dam will be back next winter, because the cause is inside the house. Honest roofing on this subject means saying so.

What Actually Ends It

Air seal, insulate, ventilate, in that order. Done together the roof deck sits close to outside temperature, the snow stays put, and your heating bill drops.

It is not glamorous work and it is usually cheaper than people expect. The full version is in Lesson 12, free, with nothing to sign up for.