Georgia residential roof building codes follow the same standards as established by the International Residential Codes (IRC). IRC provides the minimum codes standards for roof structures and other areas of construction used in most areas of the nation, including Georgia. The codes cover single-family homes, two-family dwellings and buildings with three or more townhouses.
Residential homes in Georgia must have adequate roof ventilation, including homes with attic or ceilings that attach to the underside of the roof rafters. The roof vents or openings must have protection from elements such as rain or snow. The actual opening must have dimensions between 1/16-inch and ¼-inch. Openings of ¼-inches or more must have a corrosion-resistance wire cloth screen with the required 1/16-inch and ¼-inch dimensions.
The roof must have a 2 percent, or ¼-inch per 12 inches, slope for new roofs. The design of the roof system has to protect the structure from the elements and be installed according to the International Residential Building Code; roof decks must have an “approved roof” covering. Roofers must secure the coverings to the structure using approved fasteners. The codes require the installation of coping on parapet walls. The coping material must consist of noncombustible material with a thickness at least equivalent to the parapet wall.
Residential roofs calls for the installation of flashing to prevent moisture from penetrating walls and the roof through joints, moisture permeable materials, adjoining walls and other openings. Flashing and counterflashing for residential roofs have to consist of sheet metal. Valley flashing must have a minimum width of 15 inches.
Reroofing installation does not have to conform to the code requiring the 2 percent or ¼-inch per 12 inches slope for new roofs. Generally, the building codes forbid reroofing over an existing roof when the old roof is deteriorated or water-soaked. If the existing roof foundation is inadequate for the new roof, or has two or more layers, the rules prohibit the installation of a new roofing system. If the old roof has slate, clay, cement, asbestos tile or wood shakes, the installer must remove the material.
The codes also allows for reroofing over an old roof when the new roof has it own support structure including structural metal panels, metal shingles/panels, and concrete and clay tiles over a wood shake roof. However, the installer must secure glass fiber, gypsum board, mineral fiber or another approved material over the shakes before installing the new roof.
Whether installing shingles, asphalt roll roofing wood shakes or other roofing materials, building codes states that each of the roofing materials must have compatibility with the other materials as well as the building. The vendor must deliver materials in packaging that has the manufacturer’s identification and the label of an accredited testing agency. Any materials delivered in bulk must have similar information recorded on the bill of lading or a certificate.