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Page updated Jan 13, 2011 2:33 PM

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Roof Safety During Winter Weather

Snow and cold temperatures usually force people indoors to keep warm, but the Alexandria Office of Building and Fire Code Administration (OBFCA) reminds residents to take extra precautions to protect their home’s safety during winter storms.

Building codes address the amount of snow a roof should be designed to handle, depending on snow fall averages. Most newer homes are built to these codes, but older homes, especially those with flat roofs, may have been built under different codes and therefore present a greater risk of roof collapse.

Roofs can fail for several reasons that can include:

  • Roofs designed to modern building codes should fine unless the snow exceeds 30 pounds per square foot.  However, older buildings may not designed to these standards and could be subject to problems.
  • Roof drains and/or downspouts become blocked or frozen and melting snow or rain can not adequately drain from the roof.
  • Over time, additional dead load (weight) is added to the roof, which will reduce the available live load or roof design. The increased dead load can come in the form of adding HVAC equipment or installing a new roof covering. A structural engineer should be consulted prior to adding any additional weight to the roof structure.
  • Imbalance of snow load on roof (normally caused by drifting snow.)

Warning Signs Associated with Potential Roof Collapse

Prior to a roof collapse, buildings generally exhibit signs that the roof is in distress and action should be taken by a qualified professional to mitigate a roof collapse. The following are some of the symptoms that have been reported prior to roof failure:

  • Sagging roof steel – visually deformed, cracked or split wood members
  • Sprinkler heads pushed down below ceiling tile
  • Doors that pop open
  • Doors or windows that become difficult to open
  • Bowed utility pipes or conduit attached at ceiling
  • Creaking, cracking or popping sounds
  • New or quickly expanding existing wall or ceiling cracks

Hire a roofing expert to remove snow and ice from roofs and gutters; do not climb a snow-covered roof yourself.

Heating and dryer vents should also be cleared of snow to prevent possible carbon monoxide poisoning. Do not run generators in the home, garage, other enclosed spaces, or near exterior wall openings (including soffit roof vents) as carbon monoxide can rise to dangerous, if not fatal levels.

Some of the above information provided by Zurich Services Corporation.