A plaster wall may look like drywall from the outside, but you'll discover the difference when you cut it with a reciprocating saw. Unlike drywall, which is a single sheet of gypsum board between 1/4 and 3/4 inch thick, plaster is a hard coating over wood lath. Many plaster walls include a layer of wire mesh. Cutting a plaster wall with a reciprocating saw is challenging in a few ways: The vibrations of the reciprocating saw can crack the plaster on other parts of the wall you don't intend to disturb, and you risk nicking pipes and wires behind the wall.
Things You'll Need
- 6-inch metal-cutting blade
Insert a 6-inch metal-cutting blade into a reciprocating saw to cut a plaster wall. The small teeth create less vibration than those of a wood-cutting blade, and they will cut through any wire mesh substrate you might encounter.
Make the cut from the plaster side of the wall, not from the back. Draw the line or shape you're going to cut on the plaster with a pencil.
Hold the saw at a shallow angle with respect to the wall and align the blade with the line you drew. Start the saw by depressing the trigger and lower the tip of the blade onto the wall. Hold the saw steady as you push the blade through the plaster and the materials underneath, gradually straightening the saw until it is perpendicular to the wall.
Hold the saw far enough from the wall to allow the blade to penetrate the lath by about 1/2 inch, but no farther. If pipes or wires are behind the wall, the blade should miss them, provided they aren't installed incorrectly right against the lath.
Move the saw along the line at a moderate speed to the end, keeping it straight and steady as you go. When the cut is complete, release the trigger, wait for the saw to stop, then pull it away from the wall.
Hold the foot of the saw closer to the wall when cutting horizontal lines through wall studs. This makes the blade long enough to cut through the studs.
Tips & Warnings
- If you're sure the plaster contains no wire mesh, you may be able to work faster by using a keyhole-style wood-cutting blade. Be aware, however, that there's a greater chance the teeth will catch on the wood lath and make the wall shake.
- If you suspect wires or pipes in the wall, turn off the power and water before you start cutting. Cutting through a live wire can shock or electrocute you.
- Avoid contact between the foot of the saw and the wall. It will make the wall vibrate and may crack plaster.
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