Snow Weighs an Average of 15-20#’s per cubic foot.
Failure to Clear off Decks of Snow Blamed for Many Collapses
Repeated Loading/Unloading Can Cause Great Stress to Framing
Deck Expert Bill Leys Recommends Getting Decks Inspected as Weather Permits Before Spring & Summer Use

Record breaking snow falls, especially out west have created havoc on buildings, especially roofs and decks. Snow has been credited with collapsing roofs and decks after heavy buildups that overload the decks and roofs weight carrying abilities. According to a Google search, snow weighs an average of 15-20#’s per cubic foot.
Decks on the other hand, are often designed to handle 50#’s per square foot of area. So a deck of a size 10′ x 20′ or 200 square feet, should hold 10,000 pounds. Now pile on 4 feet of snow at 80#’s per square feet using 20#’s per cubic foot. At 80″‘s per square foot, that 200 square foot deck may have 16,000 pounds of snow on it. While it might remain standing, the question becomes, what happens with repeated loading and unloading of huge amounts of weight?
That’s really going to depend on a number of things-like how old is the deck, has it been maintained etc. A newer deck is probably better equipped to handle the huge stress placed on it. Older decks with some wear and tear and degradation are likely to become likely victims of failure.
So what can you do to help avoid stressing your deck’s weight limits to their maximum & beyond? Clear off snow as soon as possible. Maybe it has to be cleared of twice or three times in a day depending on snowfall amounts. Look at the deck carefully to see if it’s sagging or swaying. Those are signs of danger and a contractor should be called immediately to assess it. Don’t use decks that sag or sway.
Even if somehow your deck in snow country doesn’t collapse this winter, that doesn’t mean it’s ok to use before summer hits. Deck Expert Bill Leys recommends that decks of every type be inspected this spring by an engineer, an experienced deck contractor, or an independent consultant who won’t be bidding on any repair work.
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