Metal roofs were traditionally used almost exclusively on low-slope roofs. In recent years they have become a popular roofing option for homes and buildings with steep-slope roofs as well. Metal roofs systems are available in an array of attractive, durable and earth-friendly styles. Prized for their long lifespan, metal roofs can be used to simulate the look of other roof systems including wood shakes, wood shingles, and even tile roofs. Price varies greatly depending on the style and type of metal roof system selected. For example, copper roofs are very expensive while tin roofs offer a more affordable option in metal roofing. Consumers who like the patina that develops on copper roofs may choose to use copper as an accent material to compliment the look and style of their building.
Metal roofing is available in two basic forms. Metal shingles can be made to look like other types of roofing shingles. The metal is layered and textured and can even be coated with stone to give a more natural look. Metal panels are also available and offer an interesting alternative appearance to the more typical shingle roof look. Metal panels also provide easy installation, especially over large areas. Both types of metal roofing are available in aluminum, steel, and copper. Specialty products manufactured out of zinc and other select metals are also available.
Metal shingle roofs and metal panel roofs have Class A fire ratings, are quite lightweight, and typically last upwards of 50 years. They are simple to maintain and, when made of recycled metal, may qualify buyers for certain tax credits. Metal roofs appeal to ecologically conscious buyers because they can be recycled and they are available with coatings to maximize energy efficiency.
Installation requirements for metal roofing:
Roof Deck: According to the NRCA metal shingles and metal shingle panels should be applied over closely spaced wood planks or continuous wood decking. Furring strips, or metal or wood purlins using a batten or counter-batten system are also acceptable roof decking for metal roofs. The NRCA recommends using caution when installing a new roof onto a roof deck made of OSB, preservative-treated wood, and wood treated with a fire-retardant coating. A qualified roofing contractor can provide information on appropriate roof decking materials for your roofing needs.
Underlayment: The underlayment provides temporary waterproofing during roof installation and acts as a permanent secondary waterproofing layer to the outermost roofing material. The NRCA recommendations for underlayment, commonly called “felt paper” specify a minimum of one layer of No. 30 asphalt-saturated felt applied horizontally in shingle fashion on roof decks having a slope of 18 degrees or more. A minimum of two layers of No. 30 asphalt-saturated felt paper is recommended for roof decks with a slope between 14 and 18 degrees. The NRCA recommends the installation of a slip sheet over the underlayment when installing metal panel roof systems. This serves to protect the underlayment from damage that can occur when the metal panels adhere to and tear the underlayment. For extremely cold climates the installation of an ice-dam membrane may be required. Check with a qualified roofing contractor for information about this additional underlayment.
Additional Requirements: When installing metal panel roofs careful consideration should be given to insulation, ventilation and the use of appropriate vapor retarding products to combat condensation which can build up on the undersides of metal roof panels.
The NRCA doesn’t recommend any specific metal roofing products or manufacturers. Guidelines have been established by the American Society for Testing Materials (ASTM) for Standing Seam Steel Roof Panel Systems, ASTM E1514, and Standing Seam Aluminum Roof Panel Systems, ASTM E1637. Carefully read metal roofing packaging and product literature to determine quality. A qualified roofing contractor can provide guidance and suggestions when selecting a metal roof system.
Metal roof systems come with warranties against manufacturing defects. These warranties typically cover failure specific to the roof product and exclude issues arising from improper installation. It is very important to fully understand the provided warranty as well as to have clear knowledge of situations which may void the warranty. Your roofing contractor should provide you with detailed warranty information pertaining to the specific metal roofing product you select, as well as warranties offered by the contractor to cover roof installation.