Diffusers · Diffusers
Surface-mount square diffuser
Drywall ceiling
ConnectionTop or side inlet box
SupportHangers to structure
Before you start
- Confirm diffuser size, ceiling opening, plenum box, neck location, backing, fastener access, and support.
- Inspect the frame, face, box, and collar.
- Verify solid backing exists above the drywall ceiling.
- Coordinate finish thickness and opening size.
Tools and materials
Surface-mount square diffuser, plenum or box, branch duct, structural hangers, backing, fasteners, sealant, level, square, and hand tools.
Lay it out
- Mark the finished ceiling opening.
- Set the plenum box to the final ceiling plane.
- Locate backing for all face screws.
Set and support it
- Support the box from structure.
- Support the branch independently.
- Keep the box square during ceiling finishing.
Make the connection
- 1
Install and support the plenum box.
- 2
Connect and seal the branch.
- 3
Finish and clean the ceiling opening.
- 4
Set the diffuser frame against the backing.
- 5
Fasten evenly.
- 6
Level and align the face.
- 7
Verify removal and service access.
Check the install
- Frame lies flat.
- Fasteners engage backing.
- Ceiling does not sag.
- Box and branch are independently supported.
- Neck connection is sealed.
Common mistakes
- Fastening into drywall only.
- Setting the box too high or low.
- Letting branch weight sag the ceiling.
- Closing the ceiling before fastener access is planned.
Stop and ask
Stop if backing or fastener access is missing, the box is unsupported, or the opening does not match the diffuser.