Q: A recent news story showed people shoveling snow off their roofs. We came from a warmer climate, and I'm not used to a lot of snow. Is this something I should plan on doing this winter?
Q: A recent news story showed people shoveling snow off their roofs. We came from a warmer climate, and I'm not used to a lot of snow. Is this something I should plan on doing this winter? Our house has a steep roof over most of the house and a flat roof on the upper rear.
A: First and foremost, stay off a snow-covered roof. But if you are determined to get on any roof, use all the necessary safety equipment available. Even the most experienced climber can slip on a snow-covered roof, which –– if not a hazard in itself –– probably has a thin layer of ice at the bottom of the snow pack.
Before attempting to shovel snow from a roof, you need to determine if the snow is heavy enough to cause damage. When the home was under construction, the builder would have taken into account the annual snow accumulation in your area and would have designed the roof supports according to the minimum building codes.
Codes refer to the amount of weight a roof can hold as ''live'' loads and ''dead'' loads. A dead load is the weight of the rafters, decking, shingles, etc., whereas a live load is the weight of something added to the roof, such as a snow load or other forces, such as wind and rain blowing on the roof.
These loads are calculated in pounds per square foot. If the live loads from a heavy wet snow are too great, the roof system could be damaged or, in extreme cases, the roof could fail. Snow can range in weight anywhere from 5 to 10 pounds per cubic foot for newly fallen fluffy snow and up to 13 to 19 pounds per cubic foot for wet or packed snow.
The majority of homes I have inspected over the past 30 years have been constructed to withstand this type of added weight, normally close to 20 per square foot. You can hire a home inspector or a carpenter to check your attic and roof bracing to make sure it will support the weight of any unusually heavy snow accumulation.
A certified home inspector can be found online at the American Society of Home Inspectors, http://www.ashi.org. Ask the person you hire about his or her experience with roof framing –– and always, always ask for references. Simply having a professional license does not ensure accuracy on the part of the licensee. Make sure to follow through and call two to three people on the reference list to help ensure a quality inspection.
Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home-improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 268, Evansville, Ind. 47702, or email d.Barnett@insightbb.com.