When my packaged a/c was installed on the roof they used ductwork that has a thin layer on insulation inside. But then because of leaks they tarred the outside. Of course the black absorbs the heat and warms the air considerably.
How best to insulate? I see the various foam insulation boards. A neighbor suggests going all out with 2" thick. I see you cut with a circular saw. I see you tape the joints with 2-7/8" Weathermate Construction Tape. But the Styrofoam sheathing can only take the UV for 90 days. I have to cover it with something, either white or reflective. What do you all suggest?
I once got an estimate from a local roofer. He wanted $3500 for like 1/2" thick insulation. No way should it cost that much. But I don't how he was going to do the job.
Don.