Good materials for flat roofs are traditional hot tar and gravel, modified bitumen, ethylene propylene diene monomer and PVC. A built-up roof uses tar and gravel. This is an attractive and relatively inexpensive option, but it creates a heavy roof.
Due to the smell and mess, people typically vacate their houses during BUR installation. The installer lays out modified bitumen in a roll. Some types require heating to adhere, but new versions use a peel-and-stick process.
EPDM is a type of rubber. Installers attach the roofing with fasteners, hold it down with stone or glue it. PVC makes a reflective and durable roof. Glue or tape hold its seams together, but this type of roof does not last as long as a seamless roof.
Hot tar and gravel roofs, also called built-up roofs, use layers of a waterproof membrane interspersed with hot tar and heavy gravel. While originally the waterproof membrane was tar paper, contractors now use fiberglass membranes, as of 2015. A built-up roof is the cheapest option, but it is heavy to install and difficult to locate a leak once it is in place.
A modified bitumen roof is a roll roofing that has one side permeated with minerals that protect against sun damage. Older modified bitumen roofs required that the installers heat the adhesive with a blow torch during the installation. Newer systems offer peel-and-stick technology that makes them easy to install for homeowners.
A rubber membrane roof, made from sheets of ethylene propylene diene monomer, is easy to install for do-it-yourself homeowners. It is also easy to patch and find the source of leaks. However, it is more expensive than other roofing options and cannot withstand punctures.
Standing seam metal roofs are the most expensive option, but they are the most durable. Most metal roofs have a 35-to 50-year warranty and can save homeowners up to 30 percent on energy costs related to heating and cooling.