Roofers apply shingles and other materials to the roofs of buildings.

A roofer's work depends on the design, material, style, and location of the client's roof. The two main styles of roofs are flat or pitched. Some roofers work on both flat and pitched roofs, while other roofers specialize in one type.

Before beginning any roofing jobs, roofers remove debris from the surfaces to be covered. For some roofs, roofers remove old shingles. Roofers usually cover a flat roof with several layers. The first layer is insulation. They spread a tar-like substance over the insulation. Roofers cover the tar with roofing felt and spread hot tar over it. They repeat these steps, sealing the seams each time. Roofers either glaze the top layer or embed it with gravel. Some flat roofs are covered with only a single layer of waterproof rubber or thermoplastic. Roofers roll the sheets over the roof's insulation and seal the seams. They apply adhesives or mechanical fasteners to keep the sheets in place.

On pitched roofs, roofers lay, cut, and tack strips of roofing felt to the roof. Then, starting from the bottom edge of the roof, they nail overlapping rows of shingles. They use chalk lines, the gauges on shingling hatchets, or lines on shingles to make sure the distance of overlap is correct. Roofers measure and cut felt and shingles to fit around vents, chimneys, and corners. They nail strips of metal or shingle over spots where shingles meet an object, such as a vent. Roofers cover exposed nail heads with roofing cement or caulking to prevent water leakage. Roofers use punches and hammers or mortar to place shingles made of tile, terra cotta, or slate.

Some roofers also waterproof concrete walls and floors. They remove any rough spots from the area to be waterproofed using a hammer and chisel or by rubbing the area with a rubbing brick. Roofers apply a waterproofing compound. The compound may be painted, sprayed, or tacked on.

Roofers may install new products that help save energy for heating and cooling. For example, some solar power panels are part of roof shingles or tiles. They install reflective coatings on roofs and solar powered attic ventilation fans. They may also install skylights, green roof systems, and solar panels.

All roofers must clean and maintain their equipment.