Although it's not a common home improvement project, occasionally it may be necessary to change the size of the ceiling hole that holds a light fixture. By far the most common example of this is when replacing an older recessed light fixture with a more modern style. Older recessed light fixtures (also called canister lights or can lights) typically used a fairly large housing that required a large ceiling hole. But modern canister lights—especially those that use newer LED light bulbs)—are often quite small. Trying to install these mini canister lights can be difficult when the hole for the old fixture is too large.
There are other instances when changing the size of the ceiling hole may be necessary. For example, you might want to replace the recessed light fixture altogether with a standard flush-mounted light fixture that requires a much smaller ceiling hole. Or perhaps you've made a mistake when installing a light fixture, cutting a hole that is too big for the new light. Another possibility: You're moving a light fixture to a new location and need to cover the old hole completely.
The project described below is a home improvement "hack" that makes use of a device more often found in the kitchens of professional bakers—a cake separator. A cake separator is a rigid polystyrene disk that bakers use to support and separate the upper tiers of tall, multi-layer cakes. Because of its 8-inch diameter, it is the perfect size for reducing a ceiling hole to accommodate both 6-inch and 5-inch recessed lights. Its smooth, rounded face and edges look like actual trim. Because it is made of hard polystyrene, a cake separator will be rigid in form and have good heat resistance yet the material is still soft enough to cut.
If you can't find a cake separator, then any thin, rigid plastic disk can serve the same function, provided it has these qualities:
- Strong enough to hold the light snug up against the ceiling drywall
- Soft enough to cut without damaging it
- Thin enough that the recessed light clips will snap down.
- Attractive and aesthetically in line with the rest of the light, with smooth outer edges
- White-colored or suitable for painting
Equipment / Tools
- Oscillating multi-tool or manual saw
- Roto-Zip or equivalent tool
- Safety glasses
- Hearing protection
- 8-inch plastic cake separator
- Recessed light fixture with paper template
- Painter's tape
- White caulk (optional)
Cut Off the Bottom Legs of the Separator Plate
Begin by cutting off the legs on the bottom of the cake separator plate. Use any tool that can cut plastic at a nearly flush angle, such as an oscillating multi-tool or even a manual saw held at a low angle.
Mark the Separator for Cutting
All recessed lights should come with a paper template for drawing a circle on the ceiling prior to cutting.This template can also be used to draw a cutout on the separator.
Center the template on the separator plate and secure it with a few strips of painter's tape. With a sharpened carpenter's pencil, scribe a circle on the separator plate. Remove the template.
Make the Cutout
Tape the separator plate down to a workbench with painter's tape on all four sides. Press down the tape so that no bubbles or folds remain.
Set a RotoZip tool to its lowest speed setting. While wearing safety glasses and hearing protection, carefully cut along the marked line. If you leave too much of the line showing, the circle will be too small to fit around the new recessed light. But if you cut beyond the line, the circle will be too loose and will not properly hold the light fixture.
Fit the New Trim Over the Light Fixture
If you have any melted plastic nibs around the cutout, scrape them off with your fingernail. Work this newly created trim piece up and over the light fixture. You likely will need to rotate the ring back and forth a bit to ease it over the protruding sections on the light fixture.
Mount the Light Fixture
Install your light fixture with its new trim piece in the ceiling hole, following the manufacterer's instructions. With its new trim in place, the fixture should fit tight against the ceiling drywall with no gaps showing. The legs of the recessed light should extend over the new trim and onto the ceiling drywall.
If there are any gaps, you can decide to keep them (if small enough), start over with a larger ring cut from new material, or give the gap a little swipe of caulk.
In addition to the cake separator remedy, there are other easy repairs you can make when the ceiling hole is the wrong size or is in the wrong place.
If the Ceiling Hole Is Too Small
When you're installing a recessed light and you accidentally make the ceiling hole too small, but only slightly, the fix is simple but messy. Use a hand-held jab saw to patiently file away drywall until the recessed light fits into the hole. Sucking away the drywall dust with a shop vacuum as you file helps to reduce dust.
If the hole is more than just slightly too small, draw a new circle around the hole and cut along that new circle.
If the Ceiling Hole Is in the Wrong Place
If your project involves moving a light fixture completely, you'll be left with a hole to fill. The easiest way to do this is by screwing two support sticks above the drywall to span the hole. Use drywall screws driven through the surrounding drywall to hold the support sticks in place, then cut a drywall patch disk to fit the hole. Drive additional screws to hold the patch to the support sticks.
The drywall disk you cut away to install the new light fixture may be exactly the right size to use as the patch.
Trim away the rough edges of the paper where the patch meets the surrounding drywall, then use drywall tape and taping compound to patch the seam. After the seam has dried and has been sanded smooth, paint or apply a surface texture to match the surrounding ceiling.
Polystyrene. California Department of Resources Recycling and Recovery.