A mud ring is a plaster or device ring fitted to a 4-inch square or 4-11/16 box, with an opening for one or two gangs or a round fixture and a raise from flat to 1-1/4 inches to suit the wall thickness. The box fastens to the stud and the ring carries the device mounting ears out to the finished surface. The name comes from the drywall mud and plaster finishers bring right up to its edge.
Five-eighths rock on this wall, so grab single-gang mud rings with 5/8 raise and nobody has to fight box extenders.
Ordering the wrong raise is a classic rookie mistake: match it to the drywall thickness plus any tile or paneling going over it.
Also heard as
- plaster ring
- device ring
- drywall ring
Related terms
Four-square box
Square steel box, 4 inches on a side, that takes a mud ring or cover and serves as the workhorse junction and device box.
Four-eleven box
Square steel box 4-11/16 inches on a side, the step up from a four-square when #10 wire or big receptacles fill it.
Goof ring
Box extension ring that brings a box set too deep back out flush with the finished wall surface.
Gem box
Single-gang metal device box with removable sides, so several can be ganged together for a row of switches.