How to Change the Size of a Ceiling Light Fixture Hole

November 23, 2021 by No Comments

It’s not an easy home improvement job, but it is possible to modify the size of the ceiling hole holding a light fixture. This is most commonly done when an older recessed lighting fixture is replaced with one of a newer style. The older recessed light fixtures, also known as canister lamps or can lighting, required a large ceiling hole because of their large housings. Modern canister lights, especially those with newer LED light bulb technology, are often very small. It can be challenging to install mini canister lights if the hole for an old fixture is too big.

Other situations may require you to change the ceiling hole’s size. You might decide to replace the entire recessed light fixture with a standard flush-mounted fixture, which will require a smaller ceiling hole. Perhaps you made a mistake in installing the light fixture, and cut too large a hole for the new light. Another option is to move a light fixture from one location to another and cover the hole completely.

This is a hack for home improvements that uses a device you’d find more often in professional bakers’ kitchens: a cake separate. A cake separator, a rigid polystyrene disc used by bakers to separate and support the top tiers of multi-layered cakes, is a rigid disk made from polystyrene. Its 8-inch diameter makes it ideal for reducing ceiling holes to fit both 6-inch and 5-inch LED recessed lights. The smooth, rounded edges and face look just like trim. Its smooth, rounded face and edges look like actual trim.

You don’t need a cake separator if you don’t have one. Any thin, rigid, plastic disk will work, as long as it is strong enough for the light to be held against the ceiling drywall. It should also be soft enough to cut the light without damaging it. It should be attractive and in keeping with the rest the light.

What you’ll need

Equipment / Tools

  • Multi-tool oscillating saw or manual saw
  • Roto-Zip, or an equivalent tool
  • Pencil
  • Safety glasses
  • Hearing protection


  • Separator for plastic cakes 8 inches in diameter
  • Recessed light fixture using a paper template
  • Tape for Painters
  • White caulk (optional).



  1. Take off the bottom legs of the separator plate

    Start by removing the legs from the bottom of your cake separator plate. You can use any tool that cuts plastic at an almost flush angle, such a multi-tool oscillating or a manual saw held at low angles.

  2. Mark the Separator to Cut

    Recessed lights must come with a template to draw a circle on the ceiling before you cut. You can also use this template to make a cutout for the separator.

    Place the template on the separator plates and secure it using a few strips painter’s adhesive. Use a sharpened pencil to draw a circle on your separator plate. Take out the template.

  3. Take the cut

    Tape the separator plate to a workbench using painter’s tape. Make sure that the tape is completely flattened.

    RotoZip to the lowest speed setting. Wear safety glasses and hearing protection while carefully cutting along the line. The circle won’t fit around the new recessed lighting if you leave too much of this line visible. If you go beyond the line, the circle won’t fit around the recessed light.

  4. Install the Trim over the Light Fixture

    Scrape any melted plastic bits around the cutout with your fingernail. This new trim piece should be placed over the light fixture. To ease the ring over protruding parts of the light fixture, you will likely need to rotate it back and forth.


  5. Mount the Light Fixture

    Follow the manufacturer’s instructions to install your light fixture using its new trim piece. The fixture should be snugly fitted against the ceiling with no gaps. The legs of the recessed lamp should extend beyond the trim to the ceiling.

    You can choose to keep any gaps (if they are small enough), or you can start over with a larger, cutter ring made from new material.


Other Fixes

You can also use the cake separator to fix a ceiling hole that is too small or in the wrong location.

  1. A Ceiling Hole Too Small Can Be Adjusted

    The fix for a ceiling hole that is too small when installing a recessed lamp is easy but messy. You can file the drywall with a handheld jab saw until it fits in the hole. As you file, use a shop vacuum to remove any drywall dust.

    If the hole is larger than slightly, draw a new circular around it and then cut the new circle.


  2. Fill a Ceiling Hole

    You will need to fill the hole if your project involves completely moving a light fixture. To span the hole, attach two support sticks to the ceiling. To hold the support sticks in position, use drywall screws to drive through the surrounding wall drywall. Then cut a patch of drywall to fit the hole. To attach the patch to the support stick, drive additional screws.


    You might be able to use the exact same size drywall disk that you used to install the new light fixture as the patch.

    The paper should be trimmed from the edges where it meets the surrounding drywall. Next, use drywall tape or taping compound to repair the seam. Once the seam is dry, sand it smooth and apply a texture to match the ceiling.

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