When estimators for Dutchess Building Specialists, a full-service remodeling company in Poughkeepsie, N.Y., price a roof, they take lots of variables into account. Square footage for ordering materials is one. To determine man hours, however, the complexity of the roof is key. Doghouse dormers, valleys, chimneys, and any penetrations all slow down installation.
"If you have a typical raised ranch with straight runs, the cost per square foot would be significantly different," owner Brian Altmann points out.
Lonnie Cox, sales and production manager at the Brothers Strong, a full-service remodeling company in Houston, calls the complex roof "dreck" and the uncomplicated one "gravy." "Gravy's the roof with only two sides. Run it up on one side, run it up on the other, put the ridge on." Dreck, on the other hand, takes days and days.
What to watch for
Because set-up and teardown account for as much as a quarter of the time on the job, factors like site accessibility, site conditions, and roof pitch all figure in calculating cost. For instance, can your supplier get a boom truck onto the site?
"If I have to send [the materials] up on a power ladder, it's going to be a little bit different," Altmann says.
Site access issues also affect tear-off. "Do you have access to the driveway, so you can get a dump truck in there?" asks Jimmy Waller, of Goff-Waller Roofing, Lakeland, Fla. "If we can, it's going to go a lot quicker." If Goff-Waller crews can't, the alternative is to spread tarps, toss the shingles down, then empty them into a truck or Dumpster. Waller estimates adding that extra step bumps up labor costs 25%.
Illinois remodeler Larry Heuvelman says not allowing enough time for tear-off is a common mistake. With a small roof, Heuvelman budgets for a two or three man crew, with three to five stripping a large roof. Roof pitch is also key to accurate estimating, because a steep pitch adds time to tear-off and installation.
It's important to know how many layers of material are on the roof now and what those layers consist of. Heuvelman once found a layer of shakes under two layers of asphalt shingles -- a discovery that slowed the tear-off process considerably. "The homeowner didn't know it and I didn't know it," he recalls. It fell under the "concealed conditions" section of his contract, but Heuvelman learned a lesson. "Now I know to look for it."
Cox once worked on a job where, unbeknownst to the estimator, "the first layer was hot mopped. We had to chip that off. The job should've taken a day, and it took five."
Failing to actually inspect the roof can cost you, too. It's only by actually walking its surface -- coupled with examining the attic -- that you can determine the condition of the framing and decking.
"It's very common for us to have to replace plywood around the chimney, or some other vulnerable area, like valleys or eaves," Altmann says. "That would occur more often than us having to replace all the decking."
Typically, Altmann includes one sheet of plywood in every contract. "After that, we charge."
But the biggest mistake you can make in an estimate is also the most obvious: Measure the roof, from up on the roof, and measure it right because, Cox says, "everything is calculated off that. And if you're off three or four squares, you have to stop the job" to get more materials.