How to Install Air Duct Vents in an Uneven Plaster Ceiling

Ducts connected to central heating and air conditioning systems carry warm and cool air throughout a home. These tubes often terminate at the ceiling, where vents diffuse the air into the room. Although duct vents typically screw into the ceiling, plaster ceilings complicate the installation. Because plaster is often uneven, the vent does not sit flush with the ceiling. The solution is to use a device called a plaster frame.

5- to 6-inch nail
Hammer
Ladder
Tape measure
Plaster frame
Safety glasses
Keyhole saw or oscillating hand tool
Power drill
2-inch by 4-inch board (optional)
Saw (optional)
1-inch screws (optional)
1/2-inch screws

Instructions

- 1
  Enter the attic space and insert a 5- to 6-inch nail into the ceiling directly beside the air duct using a hammer. Go back downstairs into the room and locate the nail. Place a ladder under the nail.
- 2
  Read the instructions for the air vent you are installing to determine the size of the ceiling hole required. Add 3/16 of an inch to both the width and the length to accommodate the plaster frame.
- 3
  Climb up on the ladder again and draw a ceiling square to the determined dimensions using a tape measure.
- 4
  Don safety glasses and cut out the square using a key hole saw or an oscillating hand tool. Pull the chunks of plaster and lathe from the ceiling opening.
- 5
  Place the plaster frame up inside the ceiling hole so the rubber foam faces up and the outer frame rests around the edges of the hole opening. The rubber foam compresses to even out the ceiling and to create an air-tight seal.
- 6
  Secure the frame to the nearby ceiling joists using the provided screws. The screw holes for the frame are on the inside portion of the frame that sits inside the ceiling. If no studs are nearby, cut a two-by-four into two pieces that span the distance between the two nearest joists. Position the boards around the frame on the sides with the screw holes and nail the boards to the joists using 1-inch screws.
- 7
  Raise the ceiling vent cover up to the plaster frame and turn it so the screws in the cover align with the screws in the frame. Insert 1/2-inch screws into the holes on the vent cover using a power drill to secure it to the ceiling.

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