How To Know When You Should Take Snow Off Your Flat Roof

Ah, winter! Beautiful blankets of lovely white snow! Crushing, heavy, wet snow on your commercial property’s roof. Dangerous, slippery, treacherous snow pushing down on your poor building’s flat roof. When the snow starts to fall, should you worry about all the snow piling up on your flat or low-slope roof? When should you take snow off your roof? 

Not Bad

A light snowfall is unlikely to stress any commercial roof. You need to know before the heavy snowfall season just what your roof can handle:

• Have you had a local, professional commercial roofer inspect the roof, including the roof deck and structure?
• Is your roof up to current building codes?
• Have any structural members within the roof deck been replaced within the past five years? 
• How did your roof behave during the previous season’s snow?

If you can say your roof is up to the job of supporting a six-inch snowfall, you may be able to get through a few early-season snow flurries without worry. But remember: low temperatures impede snowmelt, and if internal drains or exterior scuppers become choked with ice, the meltwater has nowhere to go. As meltwater freezes into ice and more snow falls, your roof becomes strained. 

How Much?

Record snowfalls throughout the season, and if possible keep track of warm (above freezing) days. If your roof is safe to walk on, have a member of your facilities crew measure the snow load. Get a visual inspection down to the top layer of your roofing material: is it coated with ice? Have freeze and thaw cycles caused layers of ice and snow to form? 

No one can tell you exactly how much snow is too much because some snow is denser and wetter than other snow. As it packs down, too, a lot of weight can build in a short vertical distance. Discuss snow load with your local commercial roofer. 

A simple rule of thumb is you have too much snow on the roof if access to your roof is blocked by snowfall. HVAC repair workers, window washers, and others may need rooftop access throughout the cold months. 

Willy-Nilly

Snow removal from a flat roof or low-slope roof cannot be done just willy-nilly. You cannot protect your commercial roof by hiring day laborers off the street to shovel your roof. You need people familiar with flat roof layouts and obstacles so ventilators, standpipes, drains, and other features are not damaged. 

Care, too, must be taken near roof perimeters. Especially during snow removal, a low-slope roof is dangerous. If you are directing workers to shovel the snow off the roof edge, they must know exactly where the edge is at all times.

Too Much!

Excessive snow load announces itself with creaks and crunches of structural members in your roof deck, whether those members are wood or steel. Listen for odd noises, monitor your building interior for signs of strain, buckling ceilings, or oddly angled sprinkler heads. 

Leaving the snow on the roof puts a strain not only on structural elements but it inhibits thawing and melting, clogs internal drains, and makes scuppers nearly useless. Even on the coldest days, a thin blanket of snow can melt and run off safely if your roof has sun exposure. This will not happen if several snowfalls build up. 

If you have any doubts about your building’s ability to handle a snow load, contact your nearby commercial roofer for help. Getting the snow off the roof becomes crucial as more warning signs accumulate. 

Where To?

Once you decide to remove snow from your low-slope or flat roof, you need to plan where the removed snow will go. Can you simply dump it over the parapet? Can it build up in a parking lot? Will you need a front-end loader to catch tossed shovelsful and neatly place it in a hauler? 

Consider the need for parking for both employees and customers if you plan to leave the snow in your parking lot. Be careful not to make the snow pile an “attractive nuisance” which exposes you to a lawsuit if a child gets hurt playing on it. 

In removing the snow, also have the crew inspect for hanging icicles, bent or displaced gutters, or other hazards at the perimeter of your building. 

Whose Job?

Your facilities crew may be able to safely remove snow from your commercial roof; your local commercial roofer definitely can. Contact your roofer before the start of the snow season to arrange an inspection, a plan for snow removal, and a second inspection after the season to assess possible damage. 

Please contact us at Vanguard Roofing today to get the experienced help you need to help your building survive the upcoming winter months. We can help with roof inspection, snow load calculations, and snow removal.