Roof repairs: Face-lift or transplant?
Aging factors
Asphalt-based shingles (used on four out of five new houses) can take the abuse for 20 to 50 years. The wide range is due to many factors, including the weight and design of the product. Weight is standard roofing language for how much the material weighs over 100 square feet, called a square.
Single-layer shingles generally weigh about 200 pounds per square.
Multilayer shingles (often called architectural shingles) that simulate slate or wood shakes can weigh more than twice as much. Warranties follow suit, in the 20-year range for the lightest shingles, more than twice as long for the heaviest shingles. But the house environment can skew the numbers.
With a sunny, windy climate that dries out shingles, they'll deteriorate faster. The same goes for the other end of the spectrum with a roof socked in by trees that regularly cover it with leaves or pine needles.
Whatever the circumstances, more than 2 million homes need a new roof each year.
Diagnosis
Instead of relying on age to make a decision about reroofing, consider the actual condition of the roof.
You can spot several indicators — even from the ground — before consulting a contractor. That helps you sort out the realistic estimates from the scams.
Start in the attic or crawl space, looking for leaks, preferably during a big rain.
Wet spots are fairly obvious and glisten in the beam of a flashlight. Excessive condensation in poorly insulated and vented attics can confuse the issue. But long-term leaks that rot plywood decking and its supporting rafters typically leave dark brown stains. They are traces of tar that wash through the roof with the water — a sure sign that the problem is a leak from the outside and not condensation from the inside.
Outside, you can check shingles close up if the roof has a low slope (walkable) and you're comfortable climbing a ladder to take a look. But you don't need to. From the ground, you can look for the four basic stages of shingle wear.
Washed-out color: Surface granules that protect the singles and add color begin to wear away. That leaves discolored, blotchy patches that are easy to see in a light-colored roof.
On a roof with dark granules, the wear is still visible as black, shiny areas. Also look for granules at the ends of downspouts. Spotty, marginal loss in a few spots doesn't cause leaks.
•Timeline: Think about reroofing in a year or so. As more bare spots of asphalt are exposed to the elements, shingles deteriorate rapidly.
Prone to cracks: As bare spots become larger and cover most of a tab (the exposed flap between slots), asphalt becomes brittle. That leads to cracking, particularly on sun-struck roofs.
•Timeline: Think about reroofing now while the shingles are still relatively flat and leak-free.
Falling apart: As the brittle tabs crack more and curl, you'll start to find little chunks of shingles on the ground and in gutters.
At this point, water can leak in through exposed nail heads.
•Timeline: No time to waste — reroof now. If curling is minimal you can replace those shingles and reroof. If curling is widespread, you have to strip the roof or new shingles won't lie flat.
Emergency: When many tabs have broken off and most of the shingles are curled, the old roof must be completely stripped.
•Timeline: It's urgent. And yes, you have to start from scratch.
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