Should you remove snow from your roof?
Short answer: Probably not, unless you have good reason to think the snow's weight exceeds your roof's capacity to hold it or that your roof is prone to ice dams. That's because any work on or around roofs has the potential for injuries. Apart from falling, you could be hit by snow or ice as it slides off the roof.
Modern, well-maintained pitched roofs can handle a surprising amount of weight. Roofs are built, at minimum, to hold about 20 pounds per square foot. It takes quite a bit of snow to weigh that much.
Snow weight depends on how wet it is. Also, fresh snow weighs less than settled snow. To get a ballpark idea of the load your roof may be carrying, you can figure that one inch of snow weighs 1.25 pounds per square foot. That means 10 inches of snow piled on your roof would weigh about 12.5 pounds per square foot – well under the capacity of most roofs. Your roof's pitch and condition, excessive rain following a snow, and how long the snow sticks around all affect how well your roof can withstand the weight. (If you really want to geek out on snow weights, try this snow weight calculator and learn more about how roofs handle loads with this oldie-but-goodie article from Popular Mechanics.)
Some points to keep in mind:
Never climb on your roof to remove snow. If roof shoveling is required, hire a professional. They have tools and techniques to do it safely. If you have solar panels, you may want to arrange in advance for snow and ice removal, so you stay powered up.
Prevent ice dams. If your gutters are clogged or freeze solid, there's a greater chance that meltwater with nowhere to go will seep under shingles and into walls, causing damage. Keep gutters flowing free with twice yearly cleaning. Electric cable deicers to warm your overhangs also may be an option for roofs with non-combustible shingles. (Just remember to unplug them when the weather warms to keep your energy bill down.)
Roof rakes help when used with caution. Removing the snow from the edge of the roof helps cut weight, improves melting when the sun comes out and reduces the risk of ice dams. If you're physically able and decide to remove snow yourself, use an extendable roof rake made for the job (check out this video of a homeowner in Minnesota raking a mindboggling amount of snow off his roof). Don't go too deep or you risk damaging your shingles. Watch for any overhead power lines. Reach only as high as you can from the ground, and stand back from the edge of your roof so you don't get hit when the snow comes down.
Use calcium chloride sparingly. Although you can buy ice-melting calcium chloride blocks to toss up on your roof, you may want to save that solution for emergency use only, such as removing an ice dam. While it's better than (cheaper) rock salt, some roofers contend that it, too, can corrode roofing nails, gutters and roof flashing over time.
Watch for these warning signs that your roof is under too much pressure:
- Your doors and windows are sticking.
- You hear creaking or popping sounds.
- You notice new cracks in the wall.
- The roof appears to be sagging.
If you notice any of those, call a roofing professional and stay elsewhere until you're certain there's no risk of a roof collapse.
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