Be prepared for snow - no matter the month. Snow loads on roofs depend on the amount and type of snow, wind, air temperature, amount of sunshine; and roof variables including shape, thermal properties, exposures, and surrounding environment. Of all these variables, wind likely has the
greatest influence on drifts and the damage they can cause.
- If your building is located in an open and particularly windy location, pay special attention to the accumulated snow from drifts.
- Pay special attention to low lying roof areas - ensure excessive snow on these areas is quickly removed. During the course of snow removal, snow from upper roof areas should not be moved to a lower roof level. Care should be taken to avoid removing snow within 2 inches of the roof covering to avoid damaging the shingles.
Understand what factors increase snow load. Although most roof designs can handle snow loads of between 20 and 40 lbs per square foot, the consistency of the snow impacts the overall load on the roof. Modern commercial building codes require a roof to withstand a minimum of 30 pounds per square foot. The design allows for a specified amount of bending typically 1 inch over a 20 foot span.
- It is the weight, not the depth of the snow, which is cause for concern. Light and fluffy snow may weigh between 5 - 20 lbs per square foot, packed snow between 20 - 40 lbs, and moisture laden snow upwards of 45 pounds per square foot. The removal of wet snow should be your priority!
Know what to look for. Signs that the snow load on your building is cause for concern include:
- doors that suddenly start to stick, particularly upstairs doorways on interior walls;
- cracks that become visible in drywall; and
- cracks in plaster around door frames.
If you suspect there's a problem, call a professional. If you suspect that your roof may have an excessive accumulation of snow, the safest decision is to hire a professional roofing contractor or professional snow removal contractor. Visit thedominion.ca to find one o four preferred vendors in your area. Before you hire a contractor, verify that they carry current liability insurance coverage - as to see their current certificate of insurance. It's important to review the certificate to ensure the policy terms and limits are adequate. You may be legally responsible for any damages that occur outside of what is stated in the policy.
Should you decide to clear some of the snow yourself,
never climb onto the roof. Use a long handled rake with an expandable handle, likely available from your hardware or home improvement store.
- Keep your employees, customers, and building safe.
