A Song of Ice and Fire – The Street Side Energy Audit

by Erik North on August 12, 2013

Ice dam


When my wife and I bought our current house, one appeal was that it was largely uninsulated. Given the choice between somewhat insulated and uninsulated, give me the blank slate every time.

We moved in September and between the start of a super busy audit season and unpacking, any desired projects were temporarily back-burnered.

We had our first big snowfall in December and soon saw just how leaky and poorly insulated the house was. The snow on the roof melted very quickly and soon after formed 4-foot icicles obscuring the street view. For the balance of the winter I kept a ladder, shovel, rake and hatchet on the ready for snow, icicle and ice dam removal.

Over the course of the winter, patterns emerged. We live in a Cape Cod with all the attendant air sealing and insulation problems. After blizzards, the snow would first melt around the chimney then the roof over the kneewall crawlspaces. The front of the house wasn’t soooo bad as there is a high level of sun exposure. The rear was considerably worse. All told, the snow melt showed where the house had issues and some pretty back ones at that.

Snow Melt as an Audit Tool

What I experienced first hand and witness every winter day while driving is how snow melts and what it says about the house. How fast did the snow melt? Is it freezing on the eaves and forming icicles? Is it forming ice dams? Is there a particular pattern to the snow melt that reveals clues about the house’s insulation? How does it compare with the neighboring houses as they were likely built in the same era. Is the snow on the ground melting away from the foundation? So many clues, so little time.

How Fast is the Snow Melting?

If I have a few hours, sometimes I will drive around neighborhoods and check out the snow on roofs. If one house has loads of icicles and ice dams, I’ll drop off a few business cards and brochures.

All snow will melt eventually. Sitting on a dark shingle roof under direct sunlight is not conducive to a long frozen life. However, comparing how quickly the snow is melting compared to other houses with similar
construction and solar orientation can highlight those with more prominent insulation and air leakage issues.

Icicles and Ice Dams

Icicles and ice dams dovetail with the snow melt. Ice dams form when snow higher on the roof melts then refreezes on the edge. If a house has heavy icicles and a nice thick ice dam, odds are very good that there are attic insulation and air sealing issues.

Melt Patterns

The patterns in which snow melts on the roof is another clue. Check out this photo from part way through my air sealing and insulating the house.

Ice and Fire

Ice and Fire

I had blocked and sealed the tops of the kneewalls but everything below is uninsulated. The melt patterns can reveal a great deal like leaky chimney chases, unsealed vents or recessed lights. Which I don’t like.

Snow melt through added heat. The question at hand is where that heat is coming from. The melt is often evidence of issues with air sealing and insulation.

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