Benefits of Metal Roofing Over Shingles
Installing Metal Roofing over Existing Asphalt Shingle Roofs
Metal roofs have the best strength to weight ratio of any roofing material, allowing metal roofs to be installed over existing asphalt shingle roofs without the need to add structural support to the roof. Union's steel roofing panels weigh 50% to 65% less per square foot than most asphalt roofing shingles. Installing metal roofing over your existing asphalt shingle roof eliminates landfill waste and saves labor costs for removing the old asphalt roof shingles.
Most roof types simply weigh too much to be installed over top of one another without adding additional structural support to the roof. Roofs are designed to support a predetermined amount of weight and the addition of subsequent layers of heavy roofing materials such as asphalt roofing shingles can cause structural damage. In these cases, removing the old asphalt roofing shingles is usually recommended, but this creates a large amount of landfill waste. In fact, asphalt roofing shingles make up over 3% of all municipal solid waste, or 6.8 million tons annually.
Because metal roofs are so light yet so strong, metal roofing panels can typically be easily installed over your existing asphalt roof shingles without the need to add structural reinforcement. The old asphalt roof shingles under the metal roof simply serve as an extra layer of insulation and water protection and pose no problems to the new metal roof. Of course, each metal roofing over shingles installation is different, so consult your licensed metal roofing contractor to confirm if your roof is suitable for a metal roofing over shingles installation.