Metal roofs are durable, environmentally friendly, safe and budget-friendly. If you’re considering an update, metal roofing installation doesn’t have to mean completely removing your old roof. In many cases, metal roofing can be installed over your existing shingles. Research building codes in your state, as many require that after two roofs have been installed, all roofing materials must be completely removed before a third roof can be put on. This protects your home’s structural integrity and your family’s safety. Carefully read contractor reviews and choose someone with extensive experience with metal roofing installation. One concern when installing metal over shingles is that over time, condensation can build on the shingles and cause the metal to rust. This will lead to rust around the panels, making them more likely to come loose in a storm. Nationally, the average cost for metal roofing installation ranges from $6,000 to $20,000. The wide price range represents different roof sizes, different types of metal, and the cost of labor in different parts of the country — and can also include the cost of removing an old shingle roof prior to installing the metal. As a line item, the average cost of removing an old roof to prepare for installing a new roof, plus adding new roof decking, costs on average about $45-$75 per square (the pro roofer’s term for 100 square feet), depending on the pitch of the roof. Always make sure you have a clearly written contract and a warranty on both the labor and the metal.