Upgrading Attic Insulation for New HVAC Equipment
Hey all – Looking for what to do in preparation for making a new HVAC system effective in my attic. The house faces almost due south (NYC area – cold wet winters, hot humid summers), it’s a late 70’s colonial with a 4/12 roof slope so not a ton of room in the attic, but enough for an air handler and ducts. The current insulation situation is whatever was builder grade insulation between the 2nd floor ceiling joists (2×6) and nothing else. The ridge is vented and there’s also gable vents on either end of the attic.
I know, I know, no ducting in the attic but moving the ducts into the already existing conditioned space is just not going to work, and doing mini splits in each of the bedrooms (see the attached picture – 2nd floor layout) would definitely cause short cycling and draining issues since they’re smaller and closed off from each other. I also want to use the other available space in the attic for storage of holiday decorations, etc. I plan to put down plywood so a double layer of insulation is not really feasible either?
I have to find a way to bring the attic temperature under control, avoid moisture issues, work with the existing design of the house and not spend a fortune doing it. My idea is to take care of air sealing the 2nd floor first, then putting baffling in between the attic rafters under the roof decking, then putting in unfaced roll insulation over the baffles. This should help the HVAC system not work as hard, plus the baffling and unfaced insulation should keep away any moisture issues, correct?
If I’m missing something or there’s a better way to do this please weigh in, thanks.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part