It s good to know that you can only choose this option if your roof has not been overlaid previously.
Overlay shingles roof.
Metal roofs offer energy savings but do cost more upfront than traditional asphalt shingles.
They also last longer and stand up to foul weather better than shingles.
An overlay roof occurs when keep your existing roof as is choosing instead to shingle on top of it.
However this can only be done once.
When you overlay a new roof you attach the new shingles or other roofing material to the existing roofing material.
This has advantages and disadvantages and each of those should be weighed carefully.