Yes, there are times when you need to cut a hole in a plaster wall. And before you do it wrong and knock big chunks of plaster from your walls or ceilings, I thought I’d give you some tips on how to cut plaster walls the right way.
I see tragically destroyed original plaster walls all the time. Usually, the damage is courtesy of a hurried plumber or electrician who doesn’t care since they aren’t the ones patching the holes.
I will warn you that cutting through nearly 1″ thick plaster is not without its messes. It is a dusty job and you can’t always be sure to avoid all the crumbling plaster, but with the right techniques, you can avoid most mishaps.
The Wrong Tools
Plaster and wood lath are extremely sensitive to vibration. Lots of shaking and vibration can cause a chain reaction that will bring a whole ceiling crashing down.
Cutting plaster without disturbing the rest of the wall requires tools that are more surgical and less shock and awe.
Unless your plans are for massive demolition, stay away from the following tools when it comes to cutting plaster.
- Reciprocating Saw (Sawzall)
- Drywall hand saw
- Hammer and chisel
The Right Tools
High speed tools work best to cut through plaster smoothly. They don’t cause the lath behind to bend and flex knocking other things loose which is what you want to avoid.
High speed tools cause much more dust than other tools, so make sure to use a HEPA vacuum with them or keep the surface moistened, both of which help control dust and protect you.
Use the following tools for surgical like precision when cutting plaster.
- Angel Grinder (w/ diamond blade)
How to Cut Plaster
Cutting plaster is not extremely difficult with the right tools, but it does make a mess so be ready with containment and cleanup. For larger areas, I use an angle grinder with a diamond blade since this can go pretty fast. For more fine tuning or for smaller cuts, I prefer the multi-tool.
Step #1 Mark Off Your Cut
Use painter’s or masking tape to mark off the areas you are going to be cutting and draw your cut line on the tape. The tape will help keep some of the crumbling plaster from falling out in the middle of your cut if there is any and it helps you see what you are cutting.
Step #2 Make Your Cut
Using either the angle grinder or multi-tool cut along your line. Make sure to finish the cuts all the way to the end so that all the lines connect. Be sure to cut all the way through the wood lath behind.
Step #3 Remove the Patch
If you’ve cut all the way through the lath, the patch should fall right out as you make your last cut. Take this time to clean up anything necessary keeping in mind that the hole doesn’t have to be perfect since it will likely be covered with a switch plate or some other escutcheon for the item you are installing.
Step #4 Cleanup
Vacuum up any remaining dust and wipe the wall down with a wet cloth to get the remaining plaster dust off.
Maybe you’re not the one doing the cutting, but these practices are still important to tell anyone working on your house since you’ll be the one patching it up.
With a little knowledge and practice, we can save antique plaster walls all across the country!