Tips and Tricks for Accurately Cutting Drywall
Unless your room is a perfect 4' x 8' square, with no openings, you will need to cut drywall to complete your project. Take time before you begin to accurately measure and purchase drywall panels to reduce the amount of cutting you will have to do. Use full sheets wherever possible during the project, and always cut the drywall panel to length so that the end falls in the center of a joist or stud. You will then be able to attach the next panel to the other half of the joist or stud.
Making cuts along the length of a sheet can be tough. One method is to snap a chalkline along the sheet and then score the line by hand. You may also use a tape measure to mark out accurate guide lines.
When you need to cut inside corners, cut one side with a drywall saw. Then score the other side of the drywall with a utility knife and snap it back as you would any other cut.
Bend the back panel away from the score line to break it along the score. It is usually easier to snap the panel away from you. Be careful to not rip the paper face when using a drywall saw. Make cuts away from the hand holding the straight edge.
Cutting the Drywall Vertically
A. Mark the panel and score it using a straight edge and a utility knife. Pass the knife just through the top layer of paper and into the core (Image 1).
B. Snap the drywall panel along the score line, and away from cut side (Image 2).
C. Score the back of the panel with a utility knife to break the paper, and snap forward to break (Image 3).
D. Rasp and sand the edges of the drywall panel to remove any bumps or imperfections (Image 4).
Marking Horizontal Guide Lines
A. Mark the panel according to your measurements. Snap a line across the panel to provide a straight line for scoring (Image 1).
B. Alternatively, use a tape measure as a straight edge to mark the cutting line (Image 2).
Circular Light Fixtures
Measure from the center of the fitting to the sides of where the drywall sheet will be attached, then transfer the measurements to a sheet of drywall. Take this mark as the center point of the hole. Use a circular hole cutter to score the hole’s outline several times, so that you may then tap it out with a hammer.
Lights Switches and Outlets
Cutting square holes takes careful measuring and marking. Measure from the side edge of where the sheet will go to the right and left sides of the box. Then measure from the top and bottom edges to the top and bottom of the box. Transfer these marks to the sheet of drywall and cut it with a saw.
Preparing to Cut Drywall
While many DIYers find that cutting the drywall is the most straightforward part of the job, it can easily turn difficult if you do not use the right tools or if your tools are not in good condition.
It is important that you always use a sharp blade when cutting drywall. A blunt blade can tear the paper face, leaving a more difficult seam to finish later.
Always score the panels before attempting to cut through them. The best way to cut a piece of drywall is to use the "score-and-snap" method shown opposite. Score along one face of the sheet and then snap it back. If there is damage done to the back of the drywall, it will not be noticed on your finished wall. Always snap the panel away from the score cut.
Cutting drywall openings can be straightforward with the right cutting tools. In addition to your basic utility knife and tape measure, you will need some of the following special tools for cutting sheets of drywall.
To make square cuts, use a T-square or framing square. Set the sheet upright with the smooth side out. Set the T-square on the top edge and line it up with your measurement. Run a utility knife along the side of the “T” to score the cut.
When making cuts around obstacles you should use a drywall saw. Be careful to not damage the paper face with an aggressive motion.
When cutting drywall to size, it is best to aim to cut larger rather than smaller. Use a rasp to shave off excess material. Never force into place a piece of drywall that is too big.
Keyhole saws are perfect for cutting around electrical boxes. Insert the tip through the drywall and cut along each side of the box.
For round cuts, use a circle cutter to get a perfect cut. A compass can also help make a good score line, if you do not have a circle cutter.
These power tools are used to cut holes for boxes and fixtures much faster and easier than cutting out by hand. However, they can create more dust than other methods.
If you need to cut window openings, it is easier to hang the drywall over the opening before cutting out the hole for the window. If your windows are already installed, but the jambs are not, you may still find it easier to install the drywall panel before cutting out the hole. But, if the entire window unit is installed in the opening, you may want to measure and cut the hole in the drywall before you install the panels.
Cutting Window Openings
A. Install the drywall in place over the opening. Mark the hole by scoring along the top of the window opening (Image 1).
B. Using the tip of a drywall saw, make an incision through the drywall (Image 2).
C. Cut along the sides of the window opening using the drywall saw (Image 3).
D. Snap the drywall forward. Trim any debris with a utility knife, then smooth the edges (Image 4).
Cutting Small Openings
A. Cut a small circular opening through the outlet box with a drywall saw (Image 1).
B. Cut around the inside of the outlet box to create the opening (Image 2).
C. Trim the drywall away from the outside of the box to make room for the box to sit inside the wall (Image 3).
D. Smooth the hole and finish. Insert the box into the hole, then wire as required (Image 4).
Copyright 2009 Dorling Kindersley Limited
Text copyright 2009 Julian Cassell and Peter Parham