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Channel in old plaster lath

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    Channel in old plaster lath

    Cutting a six inch by twenty foot channel in old plaster and wooden lath.
    What would you use to do that?

    Score the plaster then scrap it out?

    How time consuming is it to do that with a multitool?
    I assuming it's going to make a God awful mess with the vibration.

    #2
    Back in the day when we used to chase gypsum block we used a wall chaser saw. You might be able to rent one.

    https://en.wikipedia.org/wiki/Wall_chaser
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

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      #3
      Originally posted by JJWalecka View Post
      Cutting a six inch by twenty foot channel in old plaster and wooden lath.
      What would you use to do that?

      Score the plaster then scrap it out?

      How time consuming is it to do that with a multitool?
      I assuming it's going to make a God awful mess with the vibration.
      Are you cutting along the lathe or across it? A diamond blade in a circular saw set to just cut the plaster then a fine plywood blade to cut the lathe.
      I cut the plaster an inch or two wider than the lathe so it can be patched easier with thin blue board and plaster.
      Its dusty no matter what you do so plastic off your area and use a shop vac on the saw.

      Comment


        #4
        Originally posted by JJWalecka View Post
        How time consuming is it to do that with a multitool?
        It would take forever with a multitool. A circular saw is what you need as mentioned above.

        Comment


          #5
          I would use an angle grinder.
          Curt Swartz
          Electrical Contractor

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            #6
            Originally posted by curt swartz View Post
            I would use an angle grinder.
            In addition to cutting through the plaster and lathe, another important factor is straightness of cut. A straight cut is easier to repair with drywall. A circular saw is able to make much straighter cuts than an angle grinder. In fact, you could take two screws and fasten a 2x4 jig to the wall to get super straight cuts if you want.

            Also you have much better depth control with a circular saw.

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              #7
              I would try to find a blade that will cut the plaster and lath at the same time. Otherwise, you risk breaking the "keys" of plaster that hold it to the lath.

              I don't enjoy working with plaster. I hate finding metal lath even more.
              Master Electrician
              Electrical Contractor
              Richmond, VA

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                #8
                I would do whatever Larry suggest that way I would have someone to blame it on if I screw it up.

                Actually I would probably just tell them to get whoever is going to be doing the patch work to cut the channel.

                Probably 200 years of lead based paint. Sounds like about 10 sq ft to be removed.
                The 95% of people that you can't trust give the other 5% a bad name.

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                  #9
                  I'd use a grout blade on the multi tool, it will cut through old horsehair plaster like butter. Then I'd pull the lath out by hand.

                  Comment


                    #10
                    Originally posted by JJWalecka View Post
                    Cutting a six inch by twenty foot channel in old plaster and wooden lath.
                    What would you use to do that?

                    Score the plaster then scrap it out?

                    How time consuming is it to do that with a multitool?
                    I assuming it's going to make a God awful mess with the vibration.
                    Multi tool or a grinder with a ceramic blade.

                    Comment


                      #11
                      One other thing to note in commercial buildings where some fire rating was desired very old plaster contains asbestos.
                      Rob

                      Moderator

                      All responses based on the 2014 NEC unless otherwise noted

                      Comment


                        #12
                        Originally posted by peter d View Post
                        I'd use a grout blade on the multi tool, it will cut through old horsehair plaster like butter. Then I'd pull the lath out by hand.
                        I used the grout blade and oscillating tool to cut in some retro- can lights last week.
                        The job sucked! Those blades aren't cheap and I burned through 2 of them to cut-in 4 can lights!

                        I didn't anticipate that when I bid the job!
                        It took longer than anticipated and made a nasty mess of the living room!

                        Live and learn!

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                          #13
                          Originally posted by sw_ross View Post
                          It took longer than anticipated and made a nasty mess of the living room!
                          I have been there!
                          Master Electrician
                          Electrical Contractor
                          Richmond, VA

                          Comment


                            #14
                            Originally posted by sw_ross View Post
                            I used the grout blade and oscillating tool to cut in some retro- can lights last week.
                            The job sucked! Those blades aren't cheap and I burned through 2 of them to cut-in 4 can lights!

                            I didn't anticipate that when I bid the job!
                            It took longer than anticipated and made a nasty mess of the living room!

                            Live and learn!
                            Next time use a reciprocating saw with a cast iron cutting blade (or a masonry cutting blade if you can find one). Works well. Blade is thin enough to turn a tight radius.

                            Comment


                              #15
                              Originally posted by sw_ross View Post
                              I used the grout blade and oscillating tool to cut in some retro- can lights last week.
                              The job sucked! Those blades aren't cheap and I burned through 2 of them to cut-in 4 can lights!

                              I didn't anticipate that when I bid the job!
                              It took longer than anticipated and made a nasty mess of the living room!

                              Live and learn!

                              Uhh! Don't you know they make carbide grit hole saws for this? Long thread on it awhile back.

                              -Hal

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