I love standing-seam metal roofs; they look great.
When assessing existing homes, the first priority in slowing down unconditioned attic air from entering the conditioned space is to create a thermal boundary at the floor of the attic:
- Air seal attic bypasses, chases, and penetrations;
- look at recessed lights and determine if they are ICAT-rated; and then
- insulate with blown in insulation to R-38.
Once these most effective measures are in place then adding a properly installed radiant barrier makes sense.
Radiant barriers need to be cleaned every now and then as dust will reduce the performance over time.
For more information:
Read "Is there a strong argument for using a bubble insulation or foil product on trusses instead of just a radiant barrier to reduce attic temps?", a Q&A answered by Danny Kelly.