How to Cut Circles in Drywall

Cutting Circles

Cutting circular openings for ceiling canisters or other electrical boxes can sometimes be quite easy. If the canister is within a couple of feet of the edge of the drywall, you can hoist the drywall into position and reach between the joists to trace the can's perimeter onto the back of the drywall panel. A drywall lift is a valuable helper in this process.

But if you can't reach the canister, you can utilize the procedure outlined here to produce professional results.

Making the jig takes a few minutes but it will last through many remodeling projects. You probably have enough material in your scrap bin to make it, so its cost is virtually nothing.

Checklist

Time
Working with a helper, about 5 minutes per ceiling canister

Tools
Tape measure, compass, jigsaw, plumb bob with nylon line, permanent marker, drywall lift (optional but recommended)

Skills
Accurate measuring, using a plumb bob

Prep
Install ceiling canisters and have wiring inspected, if necessary.

Materials
Scrap plywood and 1x2s, screw eye, ceiling canister with supplied hole template

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Cutting Small Circles

A jab saw will quickly cut small circular openings, but a hole saw in a drill gives results that are neater and faster. Hardware stores and home centers stock hole saws in a wide range of sizes, so you're almost certain to find one that matches your needs.

Step 1

Measure the inside diameter of your ceiling canister and use a compass to draw a circle of that size onto a piece of 1/4-inch plywood. Carefully cut the circle with your jigsaw, and drill a 1/8-inch hole at the center. Also drill a hole in the perimeter of the circle. Nail the disc to a pair of 1x2 strips so the assembly won't fall into the canister. Attach one end of a nylon mason's line to a plumb bob (or use a chalk line and case) and thread the other end into the center hole and out through the perimeter hole. By pulling on the free end of the line, you can adjust the line's length while the plumb bob stays centered.

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Remodeling Canister Installs Fast

Ceiling canisters designed for new construction mount to the ceiling joists and require the careful marking procedures described above. But if you choose a remodeling-type canister, you'll simplify matters because you cut the opening after installing the panels to the ceiling. You'll still need to mark canister locations on the floor to ensure that you position them accurately, but you'll dramatically lower the overall level of difficulty. Run the wiring to the desired location, and coil a few feet of wire to ensure that you'll have enough to make the connections. Support the coil well above the lower edge of the joist so that the wire won't get pinched between the drywall and joist. After you install the drywall panel, mark and cut the opening for the canister. Make the wiring connections at the fixture's junction box and slip the canister into its opening. Pressing clips inside the cylinder secures the fixture to the ceiling panel. If the ceiling contains insulation, be sure you select a fixture with an IC (insulation contact) designation. Installing a non-IC fixture could build up dangerous levels of heat.

Step 2

Recruit a helper for the next steps. One person working at the canister adjusts the length of the string so that the plumb bob is as close to the floor as possible without touching it. The other person steadies the plumb bob until it settles. Make a dot on the floor with a permanent marker at the tip of the plumb bob, then draw a circle around the mark so that you don't misplace it.

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Step 3

Put the drywall panel for the ceiling onto a lift and carefully position it against the joists. Don't exert too much pressure, or you could crack the panel. Thread the plumb bob's line through a screw eye, and use its tip to transfer the mark on the floor onto the drywall panel. Again, you'll benefit by having a helper working at floor level.

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Step 4

Lower the ceiling panel several inches to make it easier to cut. Get the hole template that's usually furnished with the ceiling canister. Center the template, and draw its perimeter with a pencil. If you don't have a template, measure the canister, then mark the circle with a compass. Using your jab saw, cut to the outside of the line so the fit isn't too snug.

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Using Circle Cutter

You can utilize a beam-type circle cutter in two different ways. In the first method, you're essentially using it as a compass, and in the second procedure you score both sides. Both procedures start the same way. Slide the beam to the diameter you want, then turn the knob above the pivot to lock the setting. Put the pivot point into the drywall, and press the cutter firmly to score the face paper. If you're using the cutter as a compass, complete the cut with a jab saw.

To complete the hole with the cutter, press the pivot point all the way through the drywall to mark the center on the back of the panel. You may need to adjust the pivot's projection with a setscrew in the shaft. Repeat the scoring cut on the back of the drywall. A few sharp hammer blows from the front of the panel will pop out the circle.

Step 5

Raise the panel against the ceiling joists, carefully steering it into position. Drive nails or screws to hold the drywall panel in place. Miscuts with ceiling canisters are usually not a serious problem because the trim ring will conceal a flawed fit.

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Specialized Saw Speeds Circle Cutting

Buy an adjustable hole saw, and you'll breeze through the cutting steps. The saw shown here adjusts from 2-1/2 inches to 7 inches in diameter in 1/2-inch increments.

You can also purchase fixed-diameter hole saws, and some of these have replaceable blades for increased longevity. Another plus of a fixed-diameter blade is that you don't have to worry about the setting working its way loose.

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