Adding A 2nd Radiant Barrier In The Roof?

Ask The Expert – Q & ACategory: Radiant BarrierAdding A 2nd Radiant Barrier In The Roof?
RIMA Expert Staff asked 4 years ago

Good morning, I write you with hopes you can clarify for me. Our home is a new construction (1 year old) with R-38 blown insulation in the attic floor with HVAC flex duct lines (foil face, R-6 duct line) and HVAC units in the attic. Our builder installed a radiant barrier roof decking with the reflective surface pointing toward the inside of the attic. Joists are 2X10 and 2×12 for the hip roof. We are located in the Southern section of North Carolina. A local provider has recommended the installation of a radiant barrier to be attached to the underside of the rafter or bottom of the rafters. As well, he has recommended adding R-30 faced batt in those same rafters along with baffles. Hence the structure from inside out would be radiant barrier/R-30 faced batt insulation/ foamed baffles/ radiant barrier roof decking. I am not convinced the second radiant barrier he would be adding is more than just incremental and that the insulation in the rafters and baffles is over kill?

1 Answers
Best Answer
RIMA Expert Staff answered 4 years ago

You are absolutely right! Adding anything to your present insulation would be overkill and would not result in a ROI. The added radiant barrier would give you nothing and you already have all the mass insulation you need. Sorry you have been misled.
What caused you to look into adding insulation? Are you having a problem keeping the house comfortable? If so, you need to look at something other than attic insulation.