I'm pleased to present the winter 2006 online edition of Perspective, PEMCO's customer newsletter. Thank you for subscribing. We've now issued three online editions, and I'm glad you find this e-mail version useful and convenient. As always, feel free to share Perspective with your friends, and watch for the spring issue coming out in May. I welcome your feedback about Perspective. Simply send your comments to perspective@pemco.com.

Jon Osterberg
Perspective editor

Prevent ice dams in gutters

While snowy, icicle-laden roofs may remind you of a scene from Currier & Ives, what’s happening under that blanket of white is likely anything but quaint. Icicles often signal ice dams – a chronic problem in freezing weather most often caused when snow melts in the warmer middle section of a roof only to refreeze at its colder, uninsulated edge. Blocked by a “dam” of ice, water can’t flow off the roof and backs up, soaking shingles and seeping into wall cavities. Over time, framing members decay, metal fasteners corrode, paint peels and, fueled by high humidity, mold and mildew form on wall surfaces.

The best way to prevent ice dams is to ensure that your roof is evenly cold. That means stopping warm air from leaking into unheated attics by adding ceiling insulation to a depth of 12 inches (R-38) and calking gaps from fan, wire, and plumbing installations. Above that layer of insulation, the attic needs good ventilation so the air just under the roof is the same temperature as the air just over it. Attic vent openings should equal at least 1/150 of the attic’s floor area, with soffit vents (for air to enter) and ridge vents (for air to exit) running the length of the house.

When re-roofing, a rubber membrane installed under the lower section of shingles provides a good second line of defense for homes with low-pitch roofs or other design features prone to ice dams.

If it's too late for prevention and you already have an ice dam, use extreme caution when trying to remedy it. Not only could you get hurt shoveling snow off a slick roof, but your roof is brittle when cold and easily damaged by chipping and scraping. Some safer solutions: Create channels for the water to run off by pouring hot water from high windows and melt ice dams using lawn fertilizer (the kind with urea, potassium chloride, and ammonium sulfate). Or, check your Yellow Pages for a roofing professional who has the equipment and know-how to safely remove ice dams.