Roofers repair and install roofs made from a combination of some of the following: tar, asphalt, gravel, rubber, thermoplastic, metal, and shingles—all of which protect buildings and their contents from water damage. A leaky roof can damage ceilings, walls, and furnishings. Repair and reroofing—replacing old roofs on existing buildings—make up the majority of work for roofers.
There are two types of roofs—low-slope and steep-slope. Low-slope roofs rise 4 inches or less per horizontal foot and are installed in layers. Steep-slope roofs rise more than 4 inches per horizontal foot and are usually covered in shingles. Most commercial, industrial, and apartment buildings contain low-slope roofs, while the majority of residential houses have steep-slope roofs. Some roofers work on both types; others specialize.
Most low-slope roofs are covered with several layers of materials. Roofers begin by installing a layer of insulation on the roof deck, followed by applying a tarlike substance called molten bitumen on top of it. Next, they install overlapping layers of roofing felt—a fabric soaked in bitumen—over the surface. Roofers use a mop to spread hot bitumen over the felt before adding another layer of felt. This seals the seams and makes the surface waterproof. Roofers repeat these steps to build up the desired number of layers, called “plies.” The top layer is then glazed to make a smooth finish or has gravel embedded in the hot bitumen to create a rough surface.
An increasing number of low-slope roofs are covered with single-ply membranes of waterproof rubber or thermoplastic compounds. Roofers roll these sheets over the roof's insulation and seal the seams. Adhesive, mechanical fasteners, or stone ballast hold the sheets in place. Roofers must make sure the building is strong enough to hold the stone ballast.
A small but increasing number of buildings now have “green” roofs that incorporate landscape roofing systems. A landscape roofing system begins with a single or multiply waterproof layer. After it is proven to be leak free, roofers put a root barrier over it, and then layers of soil, in which trees and grass are planted. Roofers are responsible for making sure the roof is watertight and can endure the weight and water needs of the plants.
Most residential steep-slope roofs are covered with shingles. To apply shingles, roofers first lay, cut, and tack 3-foot strips of roofing felt over the entire roof. Starting from the bottom edge, roofers then nail overlapping rows of shingles to the roof. Roofers measure and cut the felt and shingles to fit intersecting roof surfaces and to fit around vent pipes and chimneys. Wherever two sections of the roof meet each other at an angle or where shingles reach a vent pipe or chimney, roofers cement or nail flashing-strips of metal or shingle over the joints to make them watertight. Finally, roofers cover exposed nail-heads with roofing cement or caulking to prevent water leakage. A similar process is used when installing tile, metal shingles, or shakes (rough wooden shingles).
Some roofers specialize in waterproofing or dampproofing masonry and concrete walls, floors, and foundations. To prepare surfaces for waterproofing, they hammer and chisel away rough spots or remove them with a rubbing brick before applying a coat of liquid waterproofing compound. They also may paint or spray surfaces with a waterproofing material or attach waterproofing membrane to surfaces. Roofers usually spray a bitumen-based coating on interior or exterior surfaces when dampproofing.
Roofing work is strenuous. It involves heavy lifting, as well as climbing, bending, and kneeling. Roofers work outdoors in all types of weather, particularly when making repairs. However, they rarely work when it rains or in very cold weather because ice can be dangerous. In northern States, roofing work is generally not performed during winter months. During the summer, roofers may work overtime to complete jobs quickly, especially before forecasted rainfall.
Workers risk slips or falls from scaffolds, ladders, or roofs, and burns from hot bitumen, but safety precautions can prevent most accidents. In addition, roofs can become extremely hot during the summer, causing heat-related illnesses. Data from the U.S. Bureau of Labor Statistics show that full-time roofers experienced a work-related injury and illness rate that was much higher than the national average.
Education & Training Required
A high school education, or its equivalent, is helpful and so are courses in mechanical drawing and basic mathematics. Although most workers learn roofing as helpers for experienced workers, some roofers train through 3-year apprenticeship programs administered by local union-management committees representing roofing contractors and locals of the United Union of Roofers, Waterproofers, and Allied Workers. Apprenticeship programs usually include at least 2,000 hours of paid long-term on-the-job training each year, plus a minimum of 144 hours of classroom instruction a year in tools and their use, arithmetic, safety, and other topics. On-the-job training for apprentices is similar to the training given to helpers, but an apprenticeship program is more structured and comprehensive. Apprentices, for example, also learn to dampproof and waterproof walls.
Trainees start by carrying equipment and material and erecting scaffolds and hoists. Within 2 or 3 months, they are taught to measure, cut, and fit roofing materials and, later, to lay asphalt or fiberglass shingles. Because some roofing materials are used infrequently, such as solar tiles, it can take several years to get experience working on all types of roofing.
Other Skills Required (Other qualifications)
Physical condition and strength, along with good balance, are essential for roofers. They cannot be afraid of heights. Experience with metal-working is helpful for workers who install metal roofing. Usually, apprentices must be at least 18 years old.
Roofers - What They Do - Page 2