Today’s residential metal roofing comes in a wide variety of styles and designs. When choosing a roof for your home, make sure that the product’s design is appropriate for your home’s construction. Most metal roofs will require solid decking (or, frequently, an existing shingle roof) and some can be installed over lathe boards or over wood shingles on lathe. Some of the more textured designs can even be installed over slate and asbestos roofs. Next, choose a product with an appropriate appearance for your home and neighborhood. You can find quality metal roofing with about any appearance, whether it is standing seam or a facsimile of shake, slate, tile, or standard shingles.
Metal roofing is made from a wide variety of metals including galvanized steel (which is zinc coating on carbon steel); galvalume steel (aluminum and zinc coating on carbon steel); exotic steels such as terne and stainless; aluminum; copper; and rolled zinc. Each metal has its own properties and the type of metal used is sometimes dictated by the design of the roofing panel. When making a wise investment in metal roofing, consider all the available options. Many consumers assume that all metal roofing is steel. However, most consumers would choose a permanently rust-free aluminum car over a steel car of similar cost; it makes sense to consider non-steel options for roofing as well.
While residential metal roofing is enjoying ever-increasing popularity, some products are fairly new. As you evaluate various products, find out how proven they are. Inquire about the systems’ flashings and accessories. Look for proven, pre-formed accessories from the manufacturer. It is particularly important to investigate how the valleys are installed. Look for an “open” valley system which carries water on top of the metal panels rather than a “closed” valley which carries water on hidden channels beneath the panels. The hidden channels on “closed” valleys have been known to clog with ice, snow, tree leaves, pine needles, and other debris, causing water to spill over the channels and infiltrate the roof system.
Metal roofing should be installed without dependence on the underlayment beneath it. However, metal roofing can develop condensation on its bottomside during certain climatic conditions. Therefore, it is jeopardizing the durability of your roof system to use a product which does not specify a quality underlayment such as 30-pound felt or one of the new polyethylene-based underlayments. If you are in an area prone to high humidity or salt air and fog, give special consideration to rust-free metals such as aluminum, copper, and zinc. Weather conditions can create the retention of condensation between the panels and the underlayment. Particularly with steel products which rest on or near the substrate such as standing seam, 5-V crimp, and low profile steel shingles, this condensation can cause them to rust from underneath. Keep in mind that failures with steel roofing occur from cut edges on the back side of the metal and rarely from the front weather side.
Because quality metal roof systems have panels which actively interlock with each other, most metal roofs are known for their wind resistance. Be sure to inquire what wind and uplift tests the systems you are considering have undergone and passed. The better products have passed 150+ mph wind-driven rain testing and/or UL 580 uplift testing exceeding 90 psf.
Some insurance companies in select states are now offering premium discounts to homeowners who choose roofs which have passed U.L. 2218 Impact Resistance testing. This test is done in four levels, with Class IV being the most severe level. Particularly if you are in a hail-prone area, it makes sense to find a product which has passed this test. Additionally, some shingle facsimile products offer backer boards to provide extra rigidity for roof areas subject to heavy foot traffic, falling tree limbs, etc. Also, look for products warranted to not loose impact resistance with age and to not chip due to hail or leak due to hail indentation or perforation.
Metal roofing can help to reflect heat and keep homes naturally cooler in warm weather. With steel, copper, and zinc roofing, energy efficiency is achieved primarily when the metal is unpainted and treated to retain its bright shininess, or when it is painted with a bright metallic or white coating. Aluminum, however, inherently reflects radiant heat. Testing done on aluminum roofing has shown it to be efficient even when painted in dark colors. This makes aluminum desirable because most homeowners do not want a white or metallic-looking roof.
Make sure that all fasteners (and other components) are of a metal which is compatible with the roofing itself. Look for a system which has concealed fasteners. Even with today’s neoprene washers and other methods of keeping moisture out of exposed screw and nail holes, any exposed holes through the panels are potential areas for water to enter the roofing system. Any water which infiltrates can, with steel products, lead to corrosion of the roofing and fasteners. Also, many metal roofing systems use “clips” to fasten the panels rather than “through fasteners” which attach the panels directly to the roof. The clips allow for expansion and contraction of the metal. Otherwise, expansion and contraction might “wallow-out” the fastener holes or cause the fasteners themselves to back out of the roof. Clips are very important to standing seam panels which sometimes have great length to them. They are also a factor with various shingle and tile systems though some heavily textured products have an inherent “accordion” effect which allows the metal to freely expand and contract without trouble.
Metal roofing, especially steel, is dependent upon a good coating for long term durability. Most product warranty lengths are determined by a combination of the metal and the coating which is used to produce that product. There are many types of finishes available and, hence, a wide range of quality. Finishes such as acrylics and siliconized polyesters are good for commercial applications where periodic re-coating for a different “look” occurs. Other finishes such as PVDF Hylar and Kynar coatings have longer lives, making them ideal for residential applications. These coatings are widely specified by architects who respect them for their long lives and color retention. Look for a finish which has proven the test of time. Look also for a finish which is warranted against such things as fading, chalking, coming loose from the base metal, and chipping due to impact.
As with any building product, success of the overall project is dependent upon proper installation. Look for products which have detailed installation instructions from the manufacturer. Look for a contractor who has substantial experience with the product you are choosing or has undergone installation training from the manufacturer. Metal roofs do not all install in the same manner. Be sure to check references of past jobs done by your installers and make sure that they have the proper licensing and insurance to work on your home.
Metal roofing is a wise investment in your home. Today’s numerous product offerings provide homeowners with a wide choice of looks and qualities. By making the proper product and contractor selection, you will substantially increase your home’s value, beauty, and comfort.
Call NSS Exteriors for a free on site quote to repair, replace or install a new residential metal roof. For details on specific options, pricing and installation, please contact us online or call 708-385-5815.
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