#19 – Types of Metal Roofing
February 23, 2017 | Filed under: Metal Roofing 101 Series, Roofing Help Videos
There are many types of metal roofs available today. While we are happy to help you in your research, let me try to break things down as simply as possible. First, there are painted metal roofs and unpainted. The unpainted ones are natural metals such as copper and zinc. Steel and aluminum roofs though will have some sort of paint finish in most cases, even if it is just an inexpensive clear coat. The clear winner in terms of the best paint finish, with no better technology on the horizon, is the PVDF finish, often sold under the trade names of Kynar and Hylar.
Next, there are roofs with exposed fasteners and those with hidden fasteners. The exposed fastened panels are often corrugated metal panels used in the metal building and agricultural markets. Exposed fasteners can be prone to loosening and leaks and they also do not allow the metal to expand and contract with temperature changes. Most homeowners will choose metal roofs with concealed fasteners that have good allowance for thermal movement of the metal. Next, there are vertical seam roofs and there are metal roofs consisting of interlocking modular panels. Those panels may be formed to look like roofing materials such as shingles, wood shakes, slate, or tile.
Our advice is to choose the look and product attributes you want for your home, locate a manufacturer, and then ask them who in your area is experienced at installing their products.
Todd Miller has spent his entire career in the metal building products manufacturing industry. He is president of Isaiah Industries, an organization recognized as one of the world’s leading metal roofing manufacturers. Todd is currently Vice President of the MRA (Metal Roofing Association) and a Past Chair of MCA (Metal Construction Association). Through his website, he strives to raise the bar on standards and practices to provide property owners with the best possible products for successful roofing projects.
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My summer home is located on a lake in PA. It is a post and beam constructrion so there is no attic. The roof and side panels are a sandwich construction consisting of a particle board top, a dry wall interior and 3.5 inches of polyurethane insulation between them. The pitch is steep with cathedral ceilings. The current roof is asphalt shingles and is about 20 years old. The portion with a southern exposure is wearing out but other sections appear to have a few years of life remaining. The site is wooded so the roof has some protection from the sun. We do not heat it in winter and temperatures are sub-freezing for a month or two with occasional sub-zeros. I’ve been considering a metal roof but now wonder after reading your very interesting and enlightening information. Any recommendations? Thank you for your help. John Kosco
One of the potential issues with insulated roof systems such as yours is it can shorten the life of asphalt shingles. This is because the insulation holds the heat at the rooftop level, aging the shingles faster. This will happen on the sunny side of the roof first of course.
One thing that I do think about is condensation on insulated roof systems. Given the fact that you do not heat in the winter, I think it’s unlikely you will have condensation issues. Have you ever done any checking to make sure that the outer layer of decking is solid and has not lost strength due to condensation in it? If this was a problem, it would be most likely to be a problem at the peak and also at joints in the decking.
If you do not notice any problems currently with moisture / condensation / weakened decking, then you should be fine, especially since it is not used in the winter. If there are signs of existing problems, then of course any weakened decking needs to be replaced. Beyond that, though, the metal roof could be held up off the roof deck with how it is secured or by choosing something like a metal shingle that has a natural air gap between the metal and the roof deck. That separation will help keep the roof deck from getting as cold, which helps reduce the chance of condensation.
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