This has advantages and disadvantages and each of those should be weighed carefully.
Overlay shingles roof.
It s good to know that you can only choose this option if your roof has not been overlaid previously.
When you overlay a new roof you attach the new shingles or other roofing material to the existing roofing material.
What you need power nailer or roofing hatchet tape measure roofing shovel or flat pry bar hammer drill carpenter s square straight cut tin snips utility knife chalkline broom.
That said overlaying asphalt shingles with a metal roof could be an option provided there is no underlying damage.
However this can only be done once.
Metal roofs offer energy savings but do cost more upfront than traditional asphalt shingles.