How To Cut a Perfectly-Sized Hole in Drywall for Lights and Electrical Boxes

How to cut holes for recessed lights

Cutting openings for recessed lights can be tricky because you have to measure over your head and then transfer the numbers to a sheet that’s sitting on the floor. It’s easy to get confused and lay out the openings from the wrong edge and wind up with holes cut in the wrong place. Then you’ve got a 55-lb.piece of trash on your hands.

When you’re staring at the sheet trying to figure out which end or side to measure from, pantomime swinging the sheet up into place instead of doing the mental gymnastics. Then mark on the sheet the side and end to pull your tape measure from. You’ll never go wrong.

You can cut drywall openings for recessed lights by laying them, drawing a circle with a compass and cutting the openings with am electric drywall saw. But if you have several recessed light openings to cut out, invest in a circle cutter. It works like a compass and cuts large circles fast and accurately.

Measure the location for the light

• Start by measuring the front and back and left and right sides of the fixture then transfer those measurements to the drywall. Write them on the framing if you have a short memory!
• Then, draw a box on the drywall to outline the hole. Draw lines from opposite corners to find the exact center.

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Mark and cut the hole in the drywall

• Transfer the measurements to the drywall and draw a box.
• Drive a nail through the center point for a pilot hole.
• Set the circle cutter to cut about 1/8 in. larger than the fixture, stick the center point in the middle and rotate the cutter while forcing the wheel into the drywall surface. Rotate the cutter several times to score the paper. The key is to cut through the paper. It may take a couple of rotations.
• Then, repeat on the other side of the drywall and knock out the plug.

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How to Cut Holes for Round Boxes

Measure and mark the drywall

• Measure and lay out the boxes exactly as you did for the recessed lights. A drywall square comes in handy for marking box positions.
• Draw the vertical lines first, then make horizontal lines by setting your pencil at the correct distance on the square and sliding the square along the finished edge.
• Use an extra round box as a pattern (or use a compass) to draw the cutout.

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Cut out the opening

• Punch the drywall saw through the drywall with the heel of your hand, then saw along the outside of the line. It’s best to slightly angle the saw so the opening in the back is larger than in the front so the box will slip into the opening easier.

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If you cut along the outside of the lines, the box should fit. But don’t assume the holes will slip perfectly over the boxes. Hang the sheet with a few screws that are placed well away from the opening. Then gently push the opening over the edge of the box until the sheet rests flat against the studs. If you ram home screws near a box without careful fitting, chances are you’ll bust out a few edges around the box.

Avoid busted edges like the plague! To fix them, you have to cut away all loose paper and broken drywall and fill the gap with setting compound. Then you have to apply tape and several coats of regular taping compound. Work carefully to avoid the hassle!

How to Cut Holes for Rectangular or Square Boxes

You’d think that cutting in rectangular boxes would be much easier than cutting in round ones. But they’re actually a little trickier. If the hole is a bit off, you’re much more likely to blow out an entire side.

Accuracy is especially critical if you have to cut several box holes in the same sheet. Also keep in mind that the electrical code allows only up to a 1/8-in. gap around electrical boxes, so you can’t cut the holes extra large. You have to fill larger gaps with setting compound. And if the gap gets too large, you’ll have to tape it as well because the outlet cover plate won’t hide it.

Measure and cut out three sides of the box

• To assure accuracy in measuring, keep the tape measure level for horizontal distances and plumb for vertical distances. Even holding the tape at a slight angle will cause slight errors in measurements that will cause problems later.
• Lay out all four sides of the box and cut through three sides with a drywall saw. When you’re sawing the hole, cut at a slight angle to make the back of the opening larger.

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• Score the fourth side with a utility knife, then snap the flap open with a little punch from the butt end of the knife.
• Slice off the flap from the backside with the utility knife. It’s cleaner and easier than sawing, and you’re less likely to damage the hole edges.

Hang the drywall and widen the opening, if needed

• Hang the sheet with just enough screws to hold it in place, keeping the screws well away from electrical boxes.
• Then, gently push the drywall into place around each box.
• If the opening doesn’t slip past the box, use a utility knife to carve away the sides until the drywall fits (Photo 4). Then finish screwing off the drywall sheet.

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