How Much Snow Can Your Roof Handle?

Though it’s not normally an issue so much here in the South, we do have our periods of heavy snow, even blizzards, and in our part of the country, homes aren’t built for this weather so when it happens it can cause problems.

Though it’s a rare phenomena, it’s important to know the risk of roof collapse due to snow accumulation, even in otherwise mild climates. Especially if your roof is older or in disrepair.


How Much Weight Can Your Roof Support?

It’s not the snow itself that’s dangerous, it’s the weight. Most residential roofs (unless damaged or decayed), no matter the climate, should be able to handle 20lbs per square foot or up to about 4 feet of accumulated fresh snow.up to 2 feet of compact snow or up to 4 inches of ice before becoming stressed.

Of course that assumes a solid, properly maintained roof as other problems such as pooling or ice dams can cause problems well before the 20lb threshold is met.

Homes in the northern climates are usually designed with heavy snows in mind thus will add significantly to this number by shoring up the roof through innovative design.  Most homes in the South aren’t built with snow in mind so during heavy snows, so pay close attention to accumulation.

What’s Your Risk Of Significant Ice or Snow Accumulation?

Whether it snows every year or every few years, if you have a chance of heavy snows it’s good to know how your roof will fare.

Homes with steep slopes have gravity working in their favor as snow that accumulates will fall the more it builds, the steeper the more snow that will simply slip off the roof.

The highest risk roofs are flat roofs and other low slope designs. as accumulations will build and build, and without intervention can quickly reach dangerous levels. If you are the owner of such a roof, having a clean up plan when snows come can be the difference between an inconvenient storm and a disaster.

Estimating Snow/Ice Weight

While it’s not likely to be a concern in the Southern climates, when the snows do come, it can be worrisome. Before you start worrying, knowing how much snow is too much can help alleviate those fears:

For fresh snow, 10 -12 inches is equal to one inch of water (5lb per sq ft) so snows that result in less than 4 feet of accumulation is fine for most homes with roofs in good condition.

Packed snow reaches 5 lbs per sq ft at around 3-5 inches. Only 2 feet of old packed snow is needed to be a danger. This is mainly a problem for the northern climates as snow stays around for day, weeks, even months.

Just 2 inches of fresh snow on top of 2 inches of packed snow can weigh as much as 60 lbs per sq ft!

For ice, one inch of ice is equal to one foot of snow.

Consult with your local roof contractor and put together a plan to not only manage the risk that come with weather but to be sure you can address any problem should an unexpected storm put your home in danger.

Cleaning snow off of a roof is no easy task, it is especially dangerous. Should you need your roof cleared of snow or other debris contact your local roof contractor.


In Metro Atlanta, call Atlanta Roofing Specialists at 770-419-2222 for your residential or commercial roof needs!


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