When Should I Shovel My Roof to Remove Snow?

When Should I Shovel My Roof to Remove Snow?

Colorado-Home-Winter-Snow-RooftopYour neighbors are shoveling their roof and you are wondering, “how did they know they needed to shovel the snow from their roof?” For many homeowners in the Colorado mountains, shoveling the roof and removing ice dams is a ritual of each and every winter. Some people will shovel just the edges while others remove all the snow from roof completely. The answer to what you should do is probably a bit more complicated than if your neighbor shovels their roof you should shovel yours.

What are the benefits of leaving snow on your roof?

Snow, up to a point, is good for your heating bill as it does add a insulating factor. Snow staying on your roof also means your home is well insulated from the outside weather. If the snow on your roof is sticking around longer than your neighbors, then your insulation is likely also in good shape.

Things to consider before you remove snow from your roof:

  • The Amount of snow that is constantly on your roof
  • The Roofing material used- Metal roofs tend to shed snow and ice better, where shingled roofs tend to hold the snow more.
  • The Pitch of your Roof – Flatter roofs (less than 3/12 pitch) tend to hold more snow moisture as snow melt is unable to fall from the roof, and ice dams are created faster.
  • Fluctuations in temperature that cause condensing of the snow without melting off. Be extra cautious of rain on to a snow filled roof. If the rain doesn’t fall from the roof, then it is captured in the snow and added to the weight on your roof.
  • The Age of your home – Older homes may have varying requirements for snow load when built as well as they may have a higher potential for rot and thermal issues.

Amount and Density of Snow Matters

The amount of snow on your roof is call Snow Load. Just measuring the depth of the snow on your roof will not give you an accurate weight of the snow on your roof. The density of the snow and ice on your roof will also be needed to determine your roofs snow load. For a quick analysis only, the basic calculation for snow load is as follows.

(S x 1.25lbs)+(I x 5.2lbs) = P

S = inches of snow on the roof (depth)
1.25lbs= Approx weight of snow for each 1-inch of depth per sq ft
I = Inches of Ice Buildup on the roof (depth)
5.2lbs= Approx weight of ice for 1-inch of depth per sq foot
P =pounds per square foot (lbs/sq ft)

Example: If the snow on my roof is 20-inches deep with .5 inches of ice, what would that equate to?

(20-inch roof snow depth x 1.25 lbs/sq ft ) + (.5-inch roof ice depth x 5.1lbs/sqft)= 27.1 lbs per sq ft of roof snow load.

In the Mountains of Colorado, anything in excess 60lbs should be considered dangerous, where most roofs should be cleared at 40lbs per square foot of roof snow load. Please not here that your home and state will likely have different building codes with lower thresholds than those of our Colorado ski town. In some areas 40lbs/sq ft may be the maximum load a roof is build to handle and roofs should be cleared at 25lbs/sq ft.

Berlet Roofing Ice DamsIcicles and Ice Buildup

Any icicles or ice buildup on your roof should be taken very seriously. Not only does the ice weigh 5 times as much as snow on the roof per sq inch, it can be a sign of bigger issues inside the roof. Snow only melts on its own for two reasons, sun or heat escaping from the home. In both cases the water will fall to the lowest point on the roof and, in most cases during the winter, freeze as icicles and ice dams. The refreezing of water has a damming effect creating an even bigger ice dam behind it. Continuous feeding of the ice dam by melting and refreezing snow melt can cause significant damage to the roof and well as interior of the home.

Water intrusion from snow melt and refreezing can also damage the interior of your home if gone unchecked. When snow melts, water often trickles through cracks in your roof. Water damage can cause ceilings, infrastructure, and roofs to warp or rot. The ugly brown stains throughout your home are a tell-tale sign of water damage, and an immediate signal that you must remove snow from your roof.

rooftop-snow-removalCheck Your Roof’s Snow Load by Hand

To check the snow load on your home, cut a 1-foot by 1-foot square the full depth of the snow from your roof into a plastic bag and weigh the bag. If there is any ice in your square foot, be sure to included it. The weight of the bag with the snow in it will tell you the weight of snow load per square foot on your roof. For Mountain towns, like Steamboat Springs, anything in excess of 60lbs should be considered dangerous. Newer homes in Steamboat Springs CO, where Berlet Roofing is based, are engineered to handle snow loads up to 75lbs/sq ft. The maximum load of your home may differ and over time most homes maximum snow load is less. In Steamboat, you should consider removing snow and ice when your sq ft snow load reaches 40lbs/sq ft. For other areas of the country, that do not experience snow at the levels of our Colorado ski town, 25 lbs/sq ft is a good target for when to remove snow from your roof. In all cases, we recommend checking with your local roofers and municipality to determine snow loads for your area, and when possible your contractor for your home’s snow load.

Check out this calculator from Cornell University for more about possible snow loads in your area: https://courses.cit.cornell.edu/arch264/calculators/example2.3/

Signs of Too Much Snow Load on Your Home

Along with seeing water spots on you ceiling, it is important to watch for cracks in your drywall. Drywall tends to crack from the changing structure it is attached to. If your roof is pushing down on your home’s structure, it may be causing warping of your walls, this can manifest as cracks in your walls. Be sure to have an inspector review these cracks in your home for other potential problems that may or may not be related to your roof’s snow load.

Another easy indicator that professionals and homeowners alike can use, is to keep an eye on center-of-the-house doors, like the door to the bedroom upstairs. If it does not stick or jam at all before the snow and it does begin to stick as the snow accumulates there is a problem.

Before and after Snow RemovalRemoving Rooftop Snow

Please be aware of the potential dangers of shoveling or raking snow from a roof. Besides the potential damage to the roofing materials and structure, there are such factors as a person sliding off the roof, falling off a ladder, overexerting themselves, or injury from snow sliding on top of them. There are even people who have died from trying to remove snow themselves. If you do decide to clear a roof, never do it alone. The potential for snow to slide off the roof is like being in an avalanche, and may cost you your life.

Think ahead about where you are going to put all that snow. If you can’t see where you are throwing snow, like over the edge of a high flat roof, have a spotter below who will keep pedestrians away and who can communicate with you by cell phone. Remember that clumps of hard snow or ice thrown from a third story roof can do serious damage to a car below. Any ladders should be tied down on both sides to prevent slipping sideways and even tied to a line over the house so it can’t be pushed backwards by sliding snow. When removing the snow, do not try to remove the last layer of ice or snow that is attached to the roof. Remove the weight above it but leave that layer to protect the roof membrane or shingles. Trying to go right down to the roofing material yourself will most likely cause the roof to leak when things begin to thaw.

Removal of ice from the edge of the roof is best done with non-salt chemical de-icers or electrical de-icing cables — not with shovels, hatches or hammers. Chopping and cutting caused more roof problems than all the ice during that big storm. Berlet Roofing utilizes Steamboat’s only low power steam ice removal system, where there are able to release the ice completely using steam, without damaging your roof.

A better alternative to consider is utilizing a roofing company, like Berlet Roofing, to remove snow and ice dams while also inspecting your roof for damage caused by melting and refreezing snow. Reputable roofing companies have tools that will help remove snow and ice from your roof down to the membrane or shingles, without causing damage to your roof, and will have the ability to inspect your roof for damage at the same time. They will also be able to complete the task quickly and will think ahead about where all that snow is going to end up. Reputable roofing companies will also have insurance to cover any unforeseen damage cause by falling snow or ice.

Other Snow Removal Resources:

Calculators:

FEMA Guides to Snow Load:

NOAA guide to Snow Loads:

Complete Snow Load Guides:

 

2017-11-30T19:55:11+00:00

2 Comments

  1. Rockford Johnson May 23, 2016 at 2:23 pm - Reply

    I learned a lot about how important it is to remove snow off of my roof by reading this article. I really like how you said that “Another easy indicator that professionals and homeowners alike can use, is to keep an eye on center-of-the-house doors, like the door to the bedroom upstairs. If it does not stick or jam at all before the snow and it does begin to stick as the snow accumulates there is a problem.” My parents have snow removed from their roof regularly when it snows and it helps to protect their roof and home.

  2. Max Jones May 23, 2017 at 10:56 am - Reply

    I really like that you talked about anything over 60 pounds needing to be removed with roof shoveling. This year is going to be my first owning a home where we’re going to have to consider roof shoveling, so its good to know when its required. I’m going to have to remember your 60 lbs suggestion, and maybe look for a roof shoveling service if it gets bad this year! Thanks for the info!

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