How to Add an Air Vent to a Room

Decide where you want to install the register. It should be as close to the center of the room and as far away from windows and drafty areas as possible. Check the attic space above the installation area to ensure there is no duct work, wiring or beams that will get in the way.

Cut the hole for the register. Measure the dimensions of the register or check the instruction manual for the exact measurements. Trace the register opening on the ceiling before you cut. Start the opening by drilling a 1/2-inch hole into each of the four corners of the rectangle you have drawn. Start from the drilled holes with a drywall saw and follow the lines drawn on the ceiling. Remove the piece of drywall.

Attach flexible duct work to the vent boot for the register. The vent boot fits over the end of the duct and will need to be clamped into place. Use aluminum tape to cover the seam between the duct and boot and eliminate potential air leaks. Carry the duct and vent boot up to the attic.

Mount the vent boot in place above the register opening as per the boot manufacturer's instructions. Some models have telescoping arms that simply need to be bolted in place while others need to be secured between the two nearest beams.

Attach the opposite end of the duct to an aluminum starting collar and fit the starting collar into the metal non-flexible duct that emerges from the air handler or furnace. Some metal ducts have pre-scored holes for the collar installation while others will need to be cut by hand with a utility knife. Cut a round hole just large enough to accommodate the starting collar. The collar should fit snugly. Tighten down the screws on the collar and duct clamp then apply aluminum tape to eliminate leaks.

Install the register grille over the opening cut in the ceiling from inside the room. Secure the grille to the drywall with the screws that came with it and ensure that the vents on the grille are open before testing the new vent.