Roofing basics shouldn't be over your head

Be sure to ask potential roofing contractors how many workers they usually put on a crew. (Photo courtesy of Angie’s List member Garrett S. of Toledo, Ohio)

Be sure to ask potential roofing contractors how many workers they usually put on a crew. (Photo courtesy of Angie’s List member Garrett S. of Toledo, Ohio)

Foundations, plumbing, electrical work, framing are all essential aspects of your home. But the integrity of each depends on a single, critical structure: your roof.

Properly installed, your roof will help keep out heat in the summer, retain heat in the winter and prevent water from infiltrating your house. While roofing from start to finish isn't a job most homeowners are qualified for (or should attempt), it's always a good idea to learn about the process. This makes you a better judge of roof contractors and their work. Here's a quick primer.

What goes into a roof

Your roof is more than just shingles. In fact, any steep-sloped roof — that's a slope of 25 percent or more — comes with five basic components.

• Roof structure. This includes both individual rafters and the larger structure they comprise, known as trusses. Trusses are engineered, triangle-shaped structures that are custom built to the proper specifications. The cannot be cut or altered but provide superior strength by transferring the roof's weight, also known as "load," to the exterior walls of your home.

• Sheathing. Typically, large sheets of oriented strand board (OSB) or plywood are used as sheathing. Workers place them over your roof structure and then attach them. Sheathing is also known as your roof's "deck."  

• Flashing. Once the deck is in place, flashing must be attached. This is usually sheet metal placed around the joints in your roof to stop leakage. Anything on your roof that juts out past the deck (chimneys, air vents or dormers with small windows) needs to have flashing to stay watertight.

• Roof coverings. These are familiar to most homeowners, with asphalt shingles standing out as the most common. Asphalt shingles are the cheapest option. While they can last up to 20 years, most homeowners find replacements are required much sooner. Wooden shakes, typically cedar or redwood, are also an option and can provider greater longevity, although they do pose a greater fire hazard. Other options such as slate or tile are also available but at a greater cost and with a greater emphasis on structure, since the weight of these coverings can be substantial.

• Drainage system. This includes eavestroughs and downspouts, all sloped properly to draw water away from your home.

Raising the roof

Installing a roof starts with the trusses. Trusses are usually made of simple two-by-four lumber but are engineered in such a way as to provide the maximum structural benefit. Unless your house has a very strange foundation footprint or you want something very much out of the ordinary on your roof, use trusses.

While it's possible to do roofing structure by hand, the time and cost involved is prohibitive. If you're going to tackle a roof project yourself, you'll need at least four helpers to get the trusses in place and installed. Then you'll have to create gable-end overhangs so that the roof doesn't flat against your truss. This lets you properly attach soffits and drainage.

Precision is essential here. Small mistakes in measurements or slope can mean big problems when you start to put on your sheathing or shingles.

Even temperature matters because most asphalt shingles recommend using a form of tar to help them adhere to the roof's surface. If it's too hot, the tar will bake on your roof deck. If it's too cold, the shingles won't stick.

What to look for in a roofer

If there's one lesson you should take away from Roofing 101, it's to hire a contractor, especially on a new home. Make sure the company is reputable, however, by asking a few critical questions.

First, always ask for licensing. Your contractor should be registered with the city and state, if applicable. Next, ask for insurance and permit documentation. Solid contractors carry substantial insurance policies in the event of damage to your home or a worker. If there's no policy, you may be the one paying.

Permits, meanwhile, are required for almost any municipal building project. Beware the builder who tells you he "doesn't need one."

Finally, make sure you receive a list of costs broken down piece by piece. It's one thing to say a roof will put you $20,000 out of pocket, but it's another to know exactly how that money gets spent. This helps you keep your contractor honest and lets you do better comparisons between providers.

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