SnowLoadsOnRoofs

MEMORANDUM

FEBRUARY 27, 2010

TO: CUSTOMERS OF SEAWRIGHT HOMES

FROM: STEVE SEAWRIGHT

RE: SNOW LOADS ON ROOFS

This E-mail [posting] and two attachments [links] are intended to be distributed via E-mail by the Secretary or webmaster of your Community Service Association to address any concerns or desire for information about snow loads on roofs that you may have had in connection with recent record snow falls.

The attachments [links] are research reports from the Universities of Wisconsin and Arkansas dealing with issues of snow and ice loads on residential roofs. Both reports note that typical roof designs are for a 30# per square foot snow load, which is the case for your home. The reports then go on to outline ranges of weight per cubic foot of snow, depending on whether the snow is relatively dry or saturated. For the snow that fell during the 3 winter storms endured thus far, weight per cubic foot likely never exceeded 10 lbs., which suggests that for a 2.5-foot accumulation, snow loads never rose over 25 lbs per square foot.

It is worth noting that both university reports urge caution about shoveling a roof already heavily loaded with snow. The damage to roof asphalt shingles that can result from shoveling or the risk of added weight precipitating roof collapse is of secondary concern compared to the harm that can occur to persons who fall from a ladder or roof while attempting to lessen the weight of accumulated snow on the roof.

Ice dams and their consequences no doubt have been experienced by many. Should anyone seek to avoid those effects being experienced again, the solution is a single ply, self-adhering, rubberized membrane, that is attached directly to roof sheathing in lieu of roofing felt/paper. One such product, manufactured by Certinteed, is, Winter Guard Roofing Membrane.

Hopefully the information provided will prove to be both informative and reassuring.