How To: Cut Plaster Walls

By Scott Sidler January 19, 2015

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.

how to cut plaster walls
Copyright: / 123RF Stock Photo

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.

*If your walls or ceilings get a positive test for lead paint make sure you follow lead safe work practices! Always wear an appropriate respirator when cutting plaster.

Use the following tools for surgical like precision when cutting plaster.

  • Multi-Tool
  • Angel Grinder (w/ diamond blade)

[wp_ad_camp_1]

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

plaster cutting
Step #1 Mark Off Your Cut
Image Copyright: Scott Sidler

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!

 

29 thoughts on “How To: Cut Plaster Walls”

  1. I own a house that was built in 1929. The ceiling (plaster) at the second floor landing almost completely fell. I need to remove the remaining part without extending into the stairwell ceiling as it descends down the stairwell.The plaster pulled away from the intact wood lath. What tool should I use? I have a Dremel tool, a five inch circular saw, and hand tools. Will any of these work? Thanks.

    Cathy

  2. For small repairs, or repairs in an inhabited room, I use a utility knife to score the plaster, repeating until I cut through the hard top coat. Then I use a dollar store putty knife to keep deepening the gash until I’m all the way through the plaster. Then with a combination of thin screwdriver, sharp chisel and putty knife I carefully chip away at the keys between the lath from the other side, working toward the gash. It’s slower than your method, which I use when I can seal off the room. But there’s no airborne dust, or little, and clean up is easy.

  3. You should rewrite the post Scott, because you left out the possibility of asbestos in the plaster. Thanks and all the best. I think you’ve helped me.

  4. I need to cut through Plaster and drywall that has wire mesh corners. What should I use? I want to save the cealing and wire mesh is in all corners.

    1. after removing the plaster and drywall using a grinder with a diamond blade change the blade to a metal cut of blade and tidy anything left behind with a pair of tin snips
      For best results use a hand held tile saw with water bottle attachment to keep the dust down. Oh don’t forget to wear your PPE

  5. We are wanting to remove the plaster to install drywall on a full wall. What would be the best way to do that with the least amount of small chunks? I don’t know if there is lathe behind the plaster. I do know in some spots there is a wire mesh.

    1. There is no real way to remove plaster without it being a crumbly, dusty mess. If the plaster is in decent shape it’s almost always a better idea to save and repair than replace with drywall.

    2. Sheetrock directly over the existing wall that is what I did leave the plaster wall in place locate your studs First and sheetrock over it

      1. after removing the plaster and drywall using a grinder with a diamond blade change the blade to a metal cut of blade and tidy anything left behind with a pair of tin snips
        For best results use a hand held tile saw with water bottle attachment to keep the dust down. Oh don’t forget to wear your PPE

  6. I’m cutting a large opening (6×5 ft) in an interior plaster wall, so I need to cut all the way through both sets of plaster and lath, as well as the studs. Would you still recommend the angle grinder and just come at it from both sides? Or is there a better tool for this type of a cut?
    Thanks!

  7. I have 1950s walls that are mortar base and skim coat plaster over 2’x4′ gyproc lath. I own and love my Multitool. My problem is that I need to cut 3 holes in the ceiling, one 14″ and two 6″.
    I have found some small width carbide blades and was going to try plunge cutting the 2 smaller holes. Any help you can provide would be very welcome.

  8. If you say that avoiding vibration is very important, I`d cut it with continuous or turbo wave diamond disc. Not a segment one as I think it makes the highest vibration

  9. Just did a full rewiring of my 1908 Craftsman and I recommend Rotozips (or any other spiral saw just haven’t used any other brands) for any work done on lath and plaster. Incredibly precise, doesn’t vibrate at all but does spit dust everywhere. Truly amazing.

  10. Are there any modifications if the plaster is on Metal Lath, or will the diamond angle grinder work as well on the metal lath?

      1. The diamond blade went through the metal lath like a knife through butter. Thanks for the information, Scott.

  11. I need to ‘shave’ approximately 5mm of old plaster off the bottom metre of the side of a chimney breast so we can fit a piece of furniture into the alcove between the chimney and outside wall. Do you have any recommendations on how to approach this or classic traps to avoid? Thanks

  12. I use a MM485 Carbide Flush Cutting Blade made by Dremel to cut through plaster and gypsum lath to install electrical boxes and prep areas for repair and I love it. I have not used it yet on wood lath.
    Thank you for all you hard work putting out this Blog.

  13. How do I remove plaster that has been put directly on to cinder blocks. A guy tried to removed the plaster and knocked a hole in three blocks. The blocks were kind of soft and shaky. Should they be repaired. They are covered with exterior bricks. Guy wants to dry wall over the crack and the rest of the plaster with green board. Should I let him before the crack is fixed.

    1. Barbara, removing plaster from cinder blocks is almost impossible or at the very least time consuming and exhausting. I would definitely repair the damaged blocks before patching the plaster. You can drywall over the plaster if you want but I don’t see what advantage you’ll gain from the drywall.

  14. You refer to a “multi-tool” in this article. By “multi-tool”, do you mean a compact rotary tool, such as a Dremel? If yes, what bit or blade do you recommend for the rotary “multi-tool”?

    Thanks!

    1. By multi-tool I’m referring to an oscillating tool for these repairs. I use a standard wood cutting blade for the lath and the grout cutting blade for the plaster. It’s slow, but for fine tuning and small areas it works great.

Leave a comment!

Keep the conversation going! Your email address will not be published.

*