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While mounting a monitor on my wall I decided to add an outlet as well. While cutting through the wall (it is an exterior wall) I noticed the wall was thicker than just drywall. The main problem I had was the paint later that kept chipping as I tried to cut a hole (with a jab saw) for the old work box, and now I have small repairs to make.

Can anyone tell me

  1. What these layers are, I know one is drywall, oddly enough its the inner layer, but I dont know the other 2.

  2. How can I repair the chipping that took place? Is it just spackle like normal drywall?

  3. Most important, is there anything I can do to keep the chipping from happening in the future?

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What these layers are, I know one is drywall, oddly enough its the inner layer, but I dont know the other 2.

You have plasterboard, followed by plaster "brown coat", followed by finish plaster "skim coat/color coat"

How can I repair the chipping that took place? Is it just spackle like normal drywall?

Traditional spackle would work

is there anything I can do to keep the chipping from happening in the future?

Score the paint film with a knife where you intend to cut, then cut on the inside of that score line. Use a saw with a finer tooth count. The normal coarse-toothed drywall jab saws are for work on unfinished drywall, where mudding, taping, and finish work hides the rough edges. Painted wall surfaces will be prone to flaking and chipping out with a saw like that. Next time use one of these:

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  • What are good search terms for those fine tooth saws?
    – MDMoore313
    Sep 10 '17 at 1:54
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    Keyhole or jab saw. Some accept reciprocating saw blades, which allows you to use metal-cutting blades with fine teeth.
    – isherwood
    Sep 10 '17 at 2:01
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Alternatively, you can cut with anything well inside of the score (thus faster) and then file/sand the edge. If the slot is wide enough use a drywall (SiC) sanding mesh/screen (again for speed), or a bastard file will generally do (get a cheap one for something like this); unlike the mesh the file will clog a bit, but not enough to prevent progress in my experience. A rasp might be better (and there exist drywall rasps, which are wider), but I didn't have any on hand when I did something like this.

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  • Thnx, I thought about filing after the fact, specifically chiseling but I like the filing idea better.
    – MDMoore313
    Sep 10 '17 at 15:11

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