# Old plaster walls



## jbfan (Apr 1, 2004)

I'm doing a rewire in a home with plaster walls and it has been an experince so far. I will need to mounts some new vanity lights and need to know how to mount them to the plaster. It seems to be as hard a concrete.
Looking for any help from those thar have been there.


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## CE1 (Dec 30, 2005)

jbfan said:


> I'm doing a rewire in a home with plaster walls and it has been an experince so far. I will need to mounts some new vanity lights and need to know how to mount them to the plaster. It seems to be as hard a concrete.
> Looking for any help from those thar have been there.


Are you talking surface mount or flush mount of the lights? If it is surface mount use wiremold. If is flush mount you may have some hard work ahead of you. We need some more details to help you, so post back.


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## jbfan (Apr 1, 2004)

It is a surface mount 6 lamp vanity light. I will mount a box, but what do I use for the ends where you would put the anchor bolts?


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## RobertWilber (Mar 5, 2006)

*cut and paste*

We hit this a lot on older common walls here. [kitchen remodels!]
I use a grinder with a carbide cutting wheel to double-notch the plaster [and brick-usually over brick], then cut out the channel created with a demo hammer with a chisel bit. [You will NEED a respirator with replaceable filters-NOT a filter mask-and goggles]
Cut a hole the same way deep enough to mount a 1900 with a plaster ring.
Run emt through the channel into the box to protect your wiring.
Use lead shields [the brick will not usually grip plastics well enough].
Plaster over it.
Works a treat!


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## mdshunk (Mar 13, 2005)

The really hard plaster was generally what you call "portland plaster", because of it's unusually high portland cement content. 

I use a 4-1/2" angle grinder with a diamond blade to cut in boxes, and use a hammer drill with masonary bit to drill for things like anchor holes. Often, once you get the plaster out of the way, you need to switch to wood blades and wood bits to cut through the wood lath by traditional means. If it's wire lath, just keep going with the diamond blade or masonary bit. 

If you drill or saw this high portland content plaster with regular wood blades or bits, they won't last very long at all. If you tried to saw out a 2" x 3" opening for a wall box with a normal sawzall blade in that stuff, all the teeth would be flat by the time you're done.

The only thing that's worse than this high portland plaster is the stuff that must have been made out of dust and spit, with a little horsehair added. Seems like the wall just wants to fall apart in chunks every time you saw out for the simplest thing. A Roto-zip with a plaster bit is was I use in this super fragile, barely holding together type of plaster. It disturbs the surrounding plaster very darned little.


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## sparkysteve (Jan 27, 2006)

I avoid it like the plauge.:no:


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