Saturday, February 7, 2015

Should You Shovel Your Roof?

Roof shoveling is a cold, hard job, and nobody wants to do it unless it's necessary. But you don't want to risk having your roof collapse on you, either. So how do you know whether your roof needs it?

There are a few factors to consider:

  • The depth of the snow on the roof
  • The size of the roof
  • The strength of the roof
  • The pitch (steepness) of the roof
  • Ice dams

Weight and Strength

It's pretty intuitive: how much snow a roof can take depends on how strong it is. Smaller roofs will naturally be stronger, per square foot, than larger roofs. This is because there's a shorter distance between the uprights (walls or porch support posts, for example). So each rafter has a shorter span and can hold more weight per square foot without sagging.

Structural Strength

How much weight your roof can take will also depend on how beefy the rafters are, how far apart they were placed, whether any of them are starting to rot, and whether the house was put together correctly. Modern construction standards call for rafters to be made of at least 2x8 lumber (ideally, 2x10) and be placed 16 inches apart.

Roof Pitch

If you got good grades in geometry, you can probably visualize how your roof's pitch affects its strength. Generally speaking, the steeper the roof is, the more its weight is transferred down to the outer walls. So a steeper roof can handle more snow without endangering its rafters.

Ice Dams

Ice dams can occur when a roof is not sufficiently insulated. Heat leaks out through the roof and melts the snow that's sitting on top of it. That melted snow runs to the edge of the roof and starts to drip off. But since it's no longer being heated, it turns to ice. Over time, that ice can build up and even crawl under the shingles and lift them up. Then when it melts on a sunny day, it usually causes water damage inside your home.

If your roof has an ice dam problem, then you need to remove the snow before it can melt and ruin your roof, your ceiling and more. And, of course, you should insulate your roof or attic to fix the problem.

When in Doubt, Shovel

It may not be fun, but it's easier to shovel your roof when it doesn't need it than to rebuild your house after the roof collapses.

New Hampshire Construction