It’s the most wonderful time of the year! Ice dam season. Now I’ll be the first to admit it’s not quite yet “the perfect storm” but I fear it’s coming. We have had some good ice dam weather but the best is yet to come. This is one of the worst of the winter hauntings, causing roof damage, staining drywall and creating the possibility of mold. So with this in mind I pulled an old but trusty text on the causes and remedies of this wonderland curse. Understanding the what’s and how’s just might save you big dollars and frustration.
What causes Ice Dams?
There is a complex interaction among the amount of heat loss from a house, snow cover, and outside temperatures that leads to ice dam formation. For ice dams to form there must be snow on the roof, and, at the same time, higher portions of the roof’s outside surface must be above 32° F while lower surfaces are below 32°F. For a portion of the roof to be below 32°F, outside temperatures must also be below 32°F. When we say temperatures above or below 32°F, we are talking about average temperature over sustained periods of time.
The snow on a roof surface that is above 32°F will melt. As water flows down the roof it reaches the portion of the roof that is below 32°F and freezes. TA DA!—an ice dam.
The dam grows as it is fed by the melting snow above it, but it will limit itself to the portions of the roof that are on the average below 32°F. So the water above backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. From the attic it could flow into exterior walls or through the ceiling insulation and stain the ceiling finish.
Preventing Ice dams.
Controlling heat loss through ceilings will help prevent the formation of ice dams.
Increasing insulation in ceiling and roof areas will help stop heated air from flowing through the roof and melting snow. Keep in mind, that if the snow no longer melts, your roof will have to carry a heavier “snow load “ Also know that with increased insulation comes concerns related to proper venting and exhausting. Contact a professional if you’re not sure how to carry out these tasks.
What to do if you have an Ice dam.
Remove snow from the roof. This eliminates one of the ingredients necessary for the formation of an ice dam. A “roof rake” and push broom can be used to remove snow, but may damage the roofing materials if not used carefully.
In an emergency situation where water is flowing into the house structure, making channels through the ice dam allows the water behind the dam to drain off the roof. Hosing with tap water on a warm day will do this job. Work upward from the lower edge of the dam. The channel will become ineffective within days and is only a temporary solution to ice dam damage. Another technique is to fill nylons with calcium chloride and tie them in to sausages, then place them on the ice dams to melt channels (don’t use salt, it can damage roof and gutter materials)
Other things to keep in mind; if a new roof is in your future, talk to your contractor about ice and water barrier. This is a protective membrane that is applied to the roof sheathing prior to shingles. Although this membrane will not stop ice dams from forming, it will protect your home from the damaging effects by sealing out the water. An experienced roofing contractor will be able to explain best practices for ice dam protection. Another consideration when dealing with ice dams is personal safety. Understand that you are risking serious injury or damage to your home when performing these tasks. If you have any doubts, contact a professional! As always, I suggest you contact the Better Business Bureau, Milwaukee NARI (National Association of the Remodeling Association) and the Metropolitan Builders Association if you are considering professional help. Understanding the origin of ice dams and how to deal with them is you first line of defense against costly repairs……………………………….NK