Excess Snow Loads on Roof

Warning Signs of Overstressed Roof Conditions During a Snow Event:

• Overstressed roof deck or framing typically displays some warning signs. Wood and steel structures may show noticeable signs of excessive deflection before failure. The following warning signs are common in wood, metal, and steel constructed buildings:
• Sagging ceiling tiles or boards, ceiling boards falling out of the ceiling grid, and/or sagging sprinkler lines and sprinkler heads
• Sprinkler heads deflecting below suspended ceilings
• Popping, cracking, and creaking noises
• Sagging roof members, including metal decking or plywood sheathing
• Bowing truss bottom chords or web members
• Doors and/or windows that can no longer be opened or closed
• Cracked or split wood members
• Cracks in walls or masonry

If any of the warning signs identified in the previous section are observed, the building should be promptly evacuated and a qualified design professional should be contacted to perform a detailed structural inspection. A qualified design professional, such as a Professional Engineer, has the experience to make an assessment of structural integrity of the building and identify steps to make the building safe.

FEMA. (2013). Risk Management Series: Snow Load Safety Guide. (FEMA P-957). Retrieved from https://www.fema.gov/sites/default/files/2020-07/fema_snow_load_2014.pdf