All buildings have roofs designed to protect the building and keep water out. In general, roofs are classified as one of two types: low slope (what many call “flat roofs”) and steep slope roofs. Many commercial, industrial, and apartment buildings have low-slope roofs, which are defined as roofs that rise four inches or less per horizontal foot. Most residential construction involves steep sloped roofs. Since each type uses different roofing materials and techniques, some roofers specialize in working on one type of roof, while others work on both.
Historically, low-slope roofs were covered with several layers of materials, including insulation, molten bitumen, a tar and pitch mixture, and gravel. Roofers install the roof in layers to make it waterproof. Layers of insulation or felt are laid on the roof surface and hot bitumen is then spread over the entire surface. The process is repeated several times to seal any seam through which water might enter the building. The final coat of bitumen is spread on the top layer and gravel is added. Roofers must also be skilled in using more recent roofing innovations, including single-ply membrane roofing materials that have few if any seams. Increasingly, they also need to know how to install “green roofs.” Green roofers not only apply roof coverings and ensure they are watertight, but also add layers of soil in which grass, plants, or even tress will be planted.
Steep-slope roofs can be covered with a variety of materials, including shingles (asphalt or engineered rubber or plastic), wood shakes, slate, metal, or tile. Workers first lay an insulating layer of felt over the entire roof surface and then, beginning at the bottom edge, nail the materials to the roof in overlapping layers. Metal strips called flashing are fastened to joints, vent pipes, and chimneys to make them watertight before the shingles, shakes, or tiles are set in place. Roofers cover nail heads with caulking or roofing cement to prevent water leakage.
Roofers have a higher than average injury rate and there are periods of time when they cannot work. They risk slipping from steep roof surfaces, falling from ladders or scaffolding, and getting burnt by hot bitumen. Cold weather, rain, ice, and snow make roofs slippery and prevent roofers from working, while hot temperatures in the summer can cause heat-related illness or injury.
Most roofers receive their training on the job, while others become apprentices. Those who begin with on-the-job training usually start by working for experienced workers as helpers and taking classes in methods and safety offered by their employer. In order to be accepted into an apprenticeship program, applicants must be at least 18 years old, be a high school graduate or have a GED, and be legally authorized to work in the United States. Apprenticeship programs are three years, and include at least 2,000 hours of paid on-the-job training and 144 hours of classroom instruction each year in subjects such as tool use, mathematics, and safety. Apprenticeship training includes not only roofing, but also training in how to damp proof and waterproof masonry and concrete walls, floors, and foundations.
The Bureau of Labor Statistics (BLS) Occupational Outlook predicts slower than average growth and good job opportunities for roofers. Employment growth is expected to be about 4 percent over the next 10 years. Growth will be driven largely by the need to repair and replace older roofs and install new ones. Since a higher than average percentage of roofers leaves the occupation, workers will also be needed to replace these individuals.
Salaries vary depending upon experience. The median hourly wage for roofers is $16.17 per hour. The middle 50 percent earn between $12.97 and $21.98 per hour. The lowest 10 percent earn less than $10.63 per hour and the highest 10 percent earn more than $28.46. Roofing apprentices receive 40 to 50 percent of the wages earned by experienced workers. The rate increases steadily as apprentices acquire additional skills.