Metal is your Lightweight Roofing!
4. Should I be concerned about the weight of a Metal Roof?
Metal makes for lightweight roofing. No need to be concerned about the weight of a metal roof. Except for one major caveat its weight is a big advantage. The truth is that even 24 gauge residential standing seam metal roofing weighs only 130 pounds per square, or per 100 square feet of roof cover. Compared to a conventional asphalt roof, that is light. A good Asphalt Shingle weighs about 240 pounds per square (Owens Corning roofing, Duration 30 year). The Owens Corning roofing shingles weigh as much as 465 pounds per square. Back to that one major caveat for a moment. When re-roofing you need to be careful of the weight you already have on your roof deck before adding another layer. Standard practice is that you can add one new layer over one old layer. However, if you already have two layers you should not add a third layer. The reasoning for this, other than it may be against code in your area, is that the weight may be too great for your structure to support. A heavy roof can be problematic in a fire for example. The fire, or a severe storm, could weaken your structure to the point that the heavy roof collapses. This can cause more damage to both contents and structure not to mention anyone who gets trapped inside and needs help. This is why I would never buy a home with, or install, a slate or cement tile roof. Too dangerous under several situations which we never expect will happen, but, they do happen. And, to mitigate the risk involved your building costs increase. You must build a more substantial truss system for the added weight of these products. But in doing so you may still encounter the same problem - a collapsed roof due to the weight of roofing materials. No thanks! Lightweight roofing is a safety issue well worth serious consideration. Also, a heavy roof can sag over time, if your support system is not built to handle the weight you add. Also, if you live in snow country you need to allow for the added weight of accumulating snow and ice. A metal roof will shed the snow and ice quickly, assuming the pitch is suitable for the amount of snow received in the area. For a lightweight roof, metal is your best choice! Another huge advantage of metal roofing! 10 FAQs
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