# drilling into 70 year old plaster walls



## SeniorSitizen (Sep 10, 2012)

The magnet method may be of benefit in a plaster wall.


How big of a bit to use for the screws? Usually the minor diameter of the screw is a acceptable size.


----------



## crankbait09 (Mar 26, 2011)

Thank you SeniorSitizen.
Ya, I saw that video too. I ran a number of different magnets along the wall with no success.

I'm assuming a masonry drill bit is the best to use without tearing the wall apart?


----------



## SeniorSitizen (Sep 10, 2012)

Is there any electric cover plates that could be pulled to look for nails through switch or receptical boxes into studs? If a drill has to be used i'd use a 1/64" twist bit or even a finish nail and swage a hole up hi or down lo and cover the holes with paint on a Q-Tip.


----------



## crankbait09 (Mar 26, 2011)

im sure there are screws or nails holding the boxes in, since they are metal with ZERO clearance on the sides. I'll check one tomorrow.

thanks for the help


----------



## Colbyt (Jan 27, 2014)

crankbait09 said:


> Unlike drywall, where the receptacle boxes are located to the right or left, depending......is it safe to assume studs are located directly behind the receptacle boxes in plaster walls?



Absolutely NOT. I've seen it done a lot of ways and often there is no stud involved. You can pull box cover and drill beside on each side to try and determine.


Over the years I found the most pop free way to drill the hard coat was to use a #8 x 1/2" HH TEK screw to penetrate that first 18/" of hardcoat. You will average about 3-5 hole starts per screw before you burn it up. It has the added bonus of being cheaper than drill bits.


----------



## diyorpay (Sep 21, 2010)

Predrilling advice: Buy mount first. Mount the part that goes on back of tv. Understand how it will hook onto a horizontal rail. With a helper, hold up rail on wall and lift tv to almost hook on to get exact placement of rail (height off floor). That's the horizontal.

The riskier vertical is next. Each receptacle box mounts to a side of a stud. Could be to right, could be left. True 2 x 4's used in those days so 2 inches wiggle room. If you have metal boxes, turn off power to that receptacle and stick a screwdriver into any available side holes in middle to rear of box. May have to also remove outlet as well. Pencil in a mark on wall where closest side of stud was found. Now another vertical mark 2 inches horizontally away. Now a mark right in the middle. That's the vertical line for drilling first hole higher up and you need to extend it to where horizontal rail will intersect. Use a level or string bob to extend line accurately. Plan on centering any horizontal rails by where you want tv centered as long as you hit enough studs. ie don't center the rails, center the tv as long as rails will be hidden behind tv.

Standard spacing of studs in walls is mostly 16 inches on center. You need to determine if that's what you have. Measure and mark in 16 inch increments from the vertical line you drew but at the horizontal rail height. Holes in rail best if exactly on the marks you made, so make sure horizontal rail is very level and trace points on wall. Now mark where the holes line up with your 16 inch spaced marks. Mark the hole spots on rail. Mark left and right on rail.
These exact intersection points 'may' be where to drill. If yours studs are 24 inches apart (another standard) you may have to start process again.

I would try Colbyt's suggestion of ruining some screws he recommends instead of ruining drill bits. Get that first penetration through plaster. When you hit stud, stop. That's a break the crust step. Move on to remaining drill points and do same. Maybe (because leveling horizontal stuff is frustrating), after first hole, hold up rail again and go to farthest assumed drill point along rail. Make sure rail is level. Drill second hole same way. If success, drill more holes on stud points as manufacturer of mount requires.

Then drill pilot holes with small drill bit through holes already made. Then screw or bolt rail to wall. Those old studs are really solid and dense. Take your time this last step. More larger pilot holes may be necessary.


----------



## Colbyt (Jan 27, 2014)

diyorpay said:


> I would try Colbyt's suggestion of ruining some screws he recommends instead of ruining drill bits. Get that first penetration through plaster. When you hit stud, stop.





The TEK screws are only used to penetrate the hard coat ( first 1/8") There after use a masonry bit in a regular drill, not a hammer drill. The undercoats are are like a soft mortar.


----------



## ron45 (Feb 25, 2014)

If you have attic access to the wall in question.

Find your studs and mark the first one by drilling a small hole down through the ceiling next to the wall.

Measure over to get the other studs needed.

I install a 3/4" piece of plywood to the face of the wall to attach the mounting bracket to. It's usually hidden from sight.


----------



## crankbait09 (Mar 26, 2011)

I thought I responded here with the final results, but it must have slipped my mind.
I ended up purchasing a stud finder that has the ability to detect, studs, deep walls, metal studs, and electrical wiring. I was really weary that it would work through plaster walls, but, to my surprise it did. It was touchy at first. I'm assuming with all the lathe and plaster behind the walls, I was getting false readings. But I kept trying, up and down, to get a consistent reading of where a stud was. Turns out, there was a stud to the left of the receptacle I talked about in OP. Once I found that with a stud finder, I pulled the cover of the receptacle, and carefully carved out a very small hole in the left corner of it, which was just big enough to get my in wall inspection camera probe into. Once inside the wall, i looked to the left, and wahoo!, there was a stud right where the stud finder said there was one. That left me feeling confident in what the stud finder was calling a stud or not.

Using the one stud, i measured over 16" to find the next one. There wasn't one there. I think it ended up being around 15"+/-. But I had 1 false drill. Missed the stud by a half inch or so. Certainly wasn't much. Drilled the new hole and it felt like I got the meat of the stud with the lag bolt.

Once I got the bracket level, and installed, I pulled on it a number of times, really hard. Sucker wasn't moving! So now it was on to the nervous part, mounting the 50 pound tv. Got it into place, set the angle, jiggled some more, but again, the tv wasn't moving off the bracket and the bracket wasn't moving away from the wall.

so i say it's good!

Only downfall to mounting a tv on a wall, for me at least, is that I like to move furniture around from time to time. It's not impossible to do, but I certainly don;t want holes in the wall every time I decide to shift things around. For now, I will leave it where it is. If I find a better layout down the road, then I will move it. Have bigger fish to fry at the moment, so buying new furniture will need to wait. Their won't be any shifting one for awhile 

thank you for the help everyone.


----------



## ScottDaley123 (Aug 28, 2020)

Careful for lead


----------

