First, the lifetime of a metal roof should be excellent- it should have no problem lasting 50 or more years. Over the long run, the durability should make the extra cost a non-issue when amortized over the lifetime of the roof.
Second, we selected a "cool" roof, which refers not to its esthetics, but its heat-reflecting properties. It has special coatings designed to reflect heat away from the house. This leads to a reduction of the urban heat island effect and also reduces the air conditioning needs of the house (but it is counterbalanced by also letting less heat from the sun into the house in winter time). To keep heat inside the house more effectively, we insulated both the upper rafters of the roof and the "floors" below the attic area.
Third, a standing seam metal roof allows for easy installation of solar panels. Solar panels can be clipped onto the seams of the roof, reducing the number of roof penetrations needed to install panels.
Cool roof color choices we considered (from left to right):
Weathered Copper, Storm Gray, Old Town Gray
We ended up choosing Weathered Copper, which has a Solar Reflectance Index (SRI) of 34 and Thermal Emittance, E=0.85.
Here's what our roof looks like, with some solar panels (we have more panels on another part of the roof).
One of the most common questions people have about a metal roof is if it's noisy. In our experience, we find that it is no more noisy than a standard shingle roof. Because the roof is attached firmly to the underlayment layers of the roof, it doesn't vibrate or have any room to ping when water hits it. The second common question is, if it's too shiny when the sun hits it. Ours is not shiny at all, because it has a matte color coating that prevents excessive glare when the sun shines on it. Overall, we are quite satisfied with our choice.
