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I don't know much about what I'm doing, and I need help. I'm trying to cut a hole in my wall for a 1 gang low voltage bracket. Do you know what type of wall this is? It's very hard to cut into with a drywall saw. Do you perhaps know how I can cut into this easier?

image of wall

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  • Just from picture it looks like some type of cement. What does it feel like? What happens if you try to press a screwdriver or hit it with a hammer? – crip659 May 16 at 17:13
  • Can we get a photo ow what is behind the Sheetrock? (Better photo) It looks much thicker than the plaster I have worked with, when overlaying I usually use thin Sheetrock but have seen DIY use 1/2”. – Ed Beal May 17 at 18:48
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That's a normal wall, sheetrock over plaster. That's how you save money when you want to renovate your home with plaster walls in bad shape, you just screw gyp board on top instead of paying for demo/dumping then gyp.

run your finger around the back side of the plaster inside the wall, you should feel some lath or if the lath is nocked away, you should feel flat/bulge/flat/etc.

Also, that's not insulation. Insulation is like cutting through butter. That's plaster. Delicious dusty plaster.

It's fine to cut into with a drywall saw, and it's normal that it will destroy your drywall saw. Most people just use whatever they have on hand, and you just have to decide which tool you want to destroy.... you can get purpose made masonry blades for your tool of choice, but then you have the tool of choice cost on top of the blade, and a drywall saw is so cheap to begin with. Cost of "replacing" drywall saw you already have if you're really sad it's not sharp as new versus: Cost of reciprocating saw and masonry blade; or, Cost of masonry reciprocating saw blade and replaceable blade handle that accepts that type of blade; or, Cost of oscillating multi tool and masonry blade.

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    +1 for delicious plaster. Also would draw attention to the textured surface, a 70s idea to hide patches of bad uneven plasterwork by ... adding horrible uneven texture everywhere. "Woodchip" covering a nightmare to remove. I'd go with a cheap oscillating tool (US$30--$40?), as relatively safe and foolproof and further uses? – user3445853 May 17 at 15:32
  • @user3445853 +1 for the cheap oscillating saw. I picked up one at Harbor Freight for $20 a few years back. It's probably going to crap out on me soon but the time I saved with the dozen times or so I've used it has been totally worth the $20. The mistake I made was to buy the blades they had next to it for 5 bucks. They lasted maybe a minute. – JimmyJames May 17 at 19:13
  • @JimmyJames I bought a $30 one 5--8y ago that's still going strong; I've bought another $20 one more recently because the new one is quick n easy 'click' blade replacement while old is with a hex/Allen key (and it loosens itself 15-20min of use). I've once borrowed a $750-or-so Feyn one, which was mostly (a) MUCH quieter, (b) much less vibration, and I think (c) less movement sideways of the blade each cycle; notable with 1/2inch blade on cheapo cutting over 3/4 wide. – user3445853 May 18 at 19:16
  • @user3445853 If you are using these all the time, quieter and less vibration is probably worth the extra cost. Mine makes an awful sound and shakes the hell out of my arm. – JimmyJames May 19 at 15:30
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That is classic Sheetrock or drywall you can tell by the paper. What is probably giving you trouble is the insulation.

I can not tell if it is spray in or sheets put in place but the fact you can cut it at all with a dry wall saw makes me believe it is insulation foam of some type because it is solid after cutting.

More information on the texture or how you are trying to cut (for wires going up down or through the wall will help provide better answers on cutting but a recrip saw or saws all usually works well where a plunge saw is the same but going much slower because elbow power is slower than electric power in this case.

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It looks like standard drywall with polystyrene insulation. You can cut that like normal drywall, with a drywall saw. Preferably a very short one, so the blade doesn't bend too much.

The outlet is probably going to be fastened by little "tabs" that grab the back of the drywall. Since you want them to grab the drywall and not the polystyrene, you'll have to remove a little bit of polystyrene where those tabs are.

Now if these panels were glued to the wall, as they usually are, it's a real headache to run the cable conduits behind.

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  • OP says "It's very hard to cut into with a drywall saw." Polystyrene it is not young grasshopper – The Ghost of Jon May 17 at 21:19
  • Look inside the hole in the picture in the question. Also have you cut this type of polystyrene backed drywall with a drywall saw? – bobflux May 17 at 21:30

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