There are two types of roofs—flat and pitched (sloped). Most commercial, industrial, and apartment buildings have flat or slightly sloping roofs. Most houses have pitched roofs. Some Nanaimo contractors work on both types; others specialize.
Most flat roofs are covered with several layers of materials. Roofing contractors first put a layer of insulation on the roof deck. Over the insulation, they then spread a coat of molten bitumen, a tar like substance. Next, they install partially overlapping layers of roofing felt—a fabric saturated in bitumen—over the surface. Nanaimo contractors use a mop to spread hot bitumen over the surface and under the next layer. This seals the seams and makes the surface watertight. Roofing contractors in Nanaimo repeat these steps to build up the desired number of layers, called “plies.” The top layer either is glazed to make a smooth finish or has gravel embedded in the hot bitumen to create a rough surface.
An increasing number of flat roofs are covered with a single-ply membrane of waterproof rubber or thermoplastic compounds. Roofing contractors roll these sheets over the roof’s insulation and seal the seams. Adhesive, mechanical fasteners, or stone ballast hold the sheets in place. The building must be of sufficient strength to hold the ballast.
Most residential roofs are covered with shingles. To apply shingles, Nanaimo contractors first lay, cut, and tack 3-foot strips of roofing felt lengthwise over the entire roof. Then, starting from the bottom edge, they staple or nail overlapping rows of shingles to the roof. Workers measure and cut the felt and shingles to fit intersecting roof surfaces and to fit around vent pipes and chimneys.
Wherever two roof surfaces intersect, or 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, Nanaimo contractors cover exposed nail heads with roofing cement or caulking to prevent water leakage. Roofing contractors who use tile, metal shingles, or shakes follow a similar process.
Some Nanaimo contractors also waterproof and damp proof masonry and concrete walls and floors. 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. When damp proofing, they usually spray a bitumen-based coating on interior or exterior surfaces.
For more information on these types of roofing visit our website at http://www.nanaimocontractor.ca/