Can I Shingle a Flat Roof?

Flat Roofs

• To avoid water problems, a roof requires a pitch of at least 1/4 inch per foot. A roof that is completely flat with no pitch whatsoever will benefit from built-up roofing. Special equipment is required when adding a slope to a flat roof. Professional roofers have this equipment and expertise; built-up roofing is not a do-it-yourself project.

Options

• Roll roofing is constructed of the same substance as shingles: asphalt-coated fiberglass or felt. The double coverage selvage type is recommended for roofs that are almost completely flat. Roll roofing does have some disadvantages. Most roll roofing, other than the double-coverage selvage, provides a single layer of protection, whereas standard shingles give you three layers. The lifespan of roll roofing is five to 12 years, and it is sensitive to cooler temperatures, below 45 degrees F. Roofing cement is required to seal seams and nail heads.

Underlayment

• Underlayment has a low vapor resistance and is a thin material, generally a type of treated felt, which is positioned underneath the shingles. This provides additional protection against weather elements. An underlayment is not required with roll roofing, but it is an option that many elect to exercise. It affords more protection, is inexpensive and is easily installed.

Installation Options

• Roll roofing can be installed either horizontally or vertically, whichever is more appropriate for your situation. This is a moderately easy do-it-yourself roofing project that takes as few as two or even only one person. Pieces are cut to measure or easily handle by the number of persons working. A 2-inch overlap seam is required and cemented and nailed down. Each piece is handled the same, cutting around chimneys and vents. The size of the roll roofing material is what makes the project go faster as the pieces are as big as you can handle.