Cutting Holes in Plasterboard

Patching Downlight Holes in Plasterboard

Circular pieces of plasterboard are very difficult to cut, so the best plan is to cut the ceiling back to a square opening around the original downlight holes using a keyhole saw. Next, cut a patch of plasterboard to fit snugly in the opening, and use plasterboard repair clips to provide a backing for the new piece. These clips can be secured to the edges of the hole with screws, and then the patch can be attached to them.

Once the patch is secured, snap off the tabs that were holding the clips in position and apply filling compound along the joints then embed jointing tape in it. Once dry, apply a coat of finishing compound, extending it about 100mm past the edges of the repair. Leave it to dry then sand with 180 grit abrasive paper, prime then paint.

Plasterboard repair kits are available from Boral, but if you’ve got a number of holes to fill, it will probably be more cost-effective to just buy a sheet of plasterboard and a few packs of clips, plus a roll of jointing tape and a bucket of filling and finishing compound.

Recessed Light

You can cut openings for recessed lights with a variety of circle-cutters or hole saws.

Circle-cutters can be adjusted from 40mm up to 270mm. Some also come with transparent cowling. For more information, visit OzGear’s website at

Hole saws, like cutters, fit into your drill chuck. When cutting plasterboard, they’re best operated at low speed. A wide range of sizes is available. Bordo manufactures continuous-grit hole saws in the five major downlight sizes: 72, 75, 89, 92 and 95mm.

A flexible dustbowl fits between the drill chuck and the hole saw, to collect the plasterboard dust as it falls – protecting your eyes and lungs (see Photos 1 and 2).

The tungsten carbide grit on these hole saws will cut plasterboard, fibreboard and cement sheeting with equal ease and accuracy.

For further information, visit Bordo’s website at

Cutting Holes in Plasterboard


The dust bowl flexes as you drill upwards. The plasterboard dust falls into the cowling (dust bowl), preventing mess and dust in your eyes.

Cutting Holes in Plasterboard


The collected plasterboard can be disposed of safely in a rubbish container. To clean the cowling, simply wipe it out with a damp rag.


Plasterboard saws make quick work of holes needed in interior walls.

Measure and lay out the positions of water and drainage pipes that will need to come through the wall. A T-square (Photo 1) comes in handy for marking pipe positions. Draw the vertical lines first, and then make horizontal lines by setting your pencil at the correct distance on the square and sliding the square along the finished edge.

Instead of using a circle cutter, trace the round hole slightly larger than the diameter of the pipe, and then cut the hole with a plasterboard saw. It’s best to angle the saw slightly, so the opening at the back is larger than at the front. This way, the pipe will slip into the opening more easily. If you cut along the outside of the lines, the pipe should fit comfortably.

TIP: Avoid broken edges like the plague! To fix them, you’ll have to cut away all loose paper and broken plasterboard, and then fill the gap with setting compound. After this, you’ll have to apply tape and several coats of taping compound. Work carefully to avoid this problem.

Water and Drainage Pipes


Mark the position of the drainage pipe using a pencil and T-square, which will slide easily along the top edge of the plasterboard panel.

Water and Drainage Pipes


Punch the plasterboard saw through the plasterboard with the heel of your hand, then saw along the outside of the line.


Only a licensed electrician can carry out electrical wiring. All power cables should be isolated before commencing any work. When the plasterboard is fixed and set, an electrician can then install and connect the outlets.

Cutting Squares and Rectangles

Square cut-outs can be quite tricky, especially if you’re fitting plasterboard over a fixed power point or air-conditioning vent.

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 errors in measurements that will cause problems later when it comes to cutting.

Fix the sheet with just enough screws to hold it in place, keeping the screws well away from electrical power points or vents. Check that the cut-outs align with the vents, ducting or power points before fixing the sheet in place.

Alternatively, measure the positions of all outlets exactly. Fix the plasterboard sheet in place, mark the outlet positions and cut them in situ.

This works well for power points, as the saw can follow the inside edge of the mounting plate. These are usually firmly fixed to a stud. Vents and ducted vacuum outlets hang free, and are best cut out before fixing the sheet in place.

Cutting Holes in Plasterboard


The starting point is to lay out all four sides of the power point and then carefully and accurately cut through three sides using a plasterboard saw.

Cutting Holes in Plasterboard


Score the fourth side with the blade of a utility knife, then snap the flap open with a light punch from the back end of the knife.

Cutting Holes in Plasterboard


Cutting from the reverse side of the plasterboard sheet, slice off the flap using a utility knife by following the fold in the paper. The fold will be obvious from the punching-through action.


Fasten the plasterboard with a few screws, and then press the cut-out over the power point. For extra clearance, shave the edges, as needed, using a utility knife.

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