THE BIG SNOW we just had has some people eyeing their roofs with concern: Will the roof hold up under the weight of double-digit depths?
The answer can depend on the age of your house. Most newer roofs are engineered to carry the weight of the roof itself plus a snow load and a wind load. But back before building codes were in force, people sometimes used undersized lumber -- either to save money or because they didn't know any better.
In that situation the roof can sag over time. But it is not likely that it will actually collapse under the weight of a heavy snow. If you have a sagging roof, it can be stabilized or sometimes jacked up to its original position. However, with very old lumber that may not work. Old lumber gets petrified in the bowed position and will lift off the walls rather than bend itself when you try to straighten it out.
Ron suspects snow as a culprit in one roof he worked on. The house, which was about 80 years old, had gaps developing where the ceilings and walls met on either side. Not hairlines, but big gaps of an inch or more in some places. It turned out that the roof was pushing out on the exterior walls because the ceiling joists were not properly attached. The ceiling joists are supposed to hold the walls in place against the weight of the roof pushing outward.
In this house, there were only one or two nails in each joist, and they had pulled loose, probably under the weight of a heavy snow. The solution will be easier to understand if you think of the roof structure as a big triangle: the base is the ceiling joist and the rafters are the angles.
So, to correct the problem, Ron drilled holes in the bottom end of every other rafter, attached a steel cable from one side to the other with a winch device in the middle. However, that alone wouldn't solve the problem. So he also used a house jack to lift the ridge board in the middle. Between lifting and cranking a quarter-inch at a time -- lift it, pull it, lift it, pull it -- the walls finally went back where they belonged. Then Ron bolted the ends of the rafters to the ends of the ceiling joists. (The bolts were massive overkill, he says, but there was no way to get a hammer in to nail the pieces together.)
The house will fall down before the roof does.
Testing the metal
Still worried about your roof withstanding another winter? Here's a thought from the Metal Roofing Alliance: Metal roofs' low weight allows them to sustain a heavier snow burden. They also shed snow quite effectively.
New techniques mean metal roofing is as attractive as well: It can look like shingles, slates, tiles, or old-fashioned ribbed "tin." The metal-roof people say metal roofs require little maintenance and typically are warranted for up to 50 years.
Metal roofs resist hail damage, manufacturers say, and often reflect heat better than other materials, contributing to energy efficiency.
Today's metal roofs are made of steel and aluminum -- some of it recycled. And most of them are recyclable in their turn.
The downside, of course, is initial cost. Metal roofing is at least four times as expensive as standard 20-year asphalt shingle roofs, and could be more if the roof has a lot of hips and valleys. However, if you're interested, call toll-free 888-638-2576 for a free video and help finding a contractor in your area.
Ron Nodine is owner of American Renovator Inc., a Baltimore design-build remodeling firm, and former president of the Remodelors Council of the Home Builders Association of Maryland. Karol Menzie is a feature writer for The Sun.
If you have questions, tips or experiences to share about working on houses, e-mail Ron at email@example.com. Or write c/o HOME WORK, The Sun, 501 N. Calvert St., Baltimore, MD 21278. Questions of general interest will be answered in the column; comments, tips and experiences will be reported in occasional columns.