Ducting - Single return requires transfer grilles to provide path and avoid pressurizing bedrooms, as shown in the figures at right. Appropriate sizing for ducts, including these pressure relief methods, can be found see Figures 12a-d or go to Cooling System Sizing Pro.
Local acceptance - This assembly may require discussion with the local building code official. See our Unvented Roof Summary Article for assistance.
CHEAT SHEET: Google-Microsoft Energy Smackdown, PowerMeter vs. Hohm