Which is better for trunk lines - Metal or Fiberboard (I think that's the right name)? I'm building a 1 1/2 story home and the HVAC contractor says that fiberboard is best in the attic for the upstairs unit because metal trunks will absorb heat (I live in Alabama) and cause the system to lose effeciency. He says metal trucks in the basement for the lower unit.
Is he feeding me a load of bull?
Thanks for your help!!