How do I find a stud in a plaster wall?

Exactly as the question states... I have a TV Wall mount, and the wall I want to put it on is an old plaster wall. How do I find a stud? The stud finder gave me way too many false positives.

I also want to know on a plaster wall. On a drywall wall I have much better luck with a strong magnet than a stud finder, as the magnet will hold itself to the drywall screws.

I'm assuming it's lath and plaster.  If so you'll want to use a metal scanner of some sort (or a really strong magnet) which will look for the row of nails attaching the laths to the stud. Zircon makes a cheap decent one.

I usually drill 16-20 holes and eventually hit one.

small explosives. They have tannerite on sale at Academy Sports right now.

I use togglers.  That way I can just hang the tv where I want it without regard to hunting for a stud.  With probably 50+ tvs hung I have yet to have one fall.

KyAllroad (Jeremy) said:

I use togglers.  That way I can just hang the tv where I want it without regard to hunting for a stud.  With probably 50+ tvs hung I have yet to have one fall.

More info?

First, look for the nails in the baseboard, chair rail, or crown molding. 

Then, use a Magnetic stud finder (not the density electronic ones)

Search for the row of nails in the lath strips. 

This assumes wood lath. If it is extruded metal lath or gyp lath, it won't work. 

mtn said:

KyAllroad (Jeremy) said:

I use togglers.  That way I can just hang the tv where I want it without regard to hunting for a stud.  With probably 50+ tvs hung I have yet to have one fall.

More info?

There are several variations. 

The best are strap-toggles (by Hillman, or other)

mtn said:

KyAllroad (Jeremy) said:

I use togglers.  That way I can just hang the tv where I want it without regard to hunting for a stud.  With probably 50+ tvs hung I have yet to have one fall.

More info?

http://www.toggler.com/

Is the TV wider then 16"?  Then its not an issue.  Studs are almost always 16" on center separation.  You can make an educated guess from a wall and start putting small nails in the wall every 1" (since the studs are 1.25").  Eventually you will hit the stud.  Put a few more in to find the limits of the stud.

Worst case you end up with a few small holes that the TV will cover.  Putting a bit of wall patch in the holes is an option of course.

In reply to aircooled :

Plaster walls are rarely on 16" centers. Often, they are very odd. The overall distance divided evenly by however many studs they had. 

Stefan said:

mtn said:

KyAllroad (Jeremy) said:

I use togglers.  That way I can just hang the tv where I want it without regard to hunting for a stud.  With probably 50+ tvs hung I have yet to have one fall.

More info?

http://www.toggler.com/

Yup, those.  Use them by the bushel.  Handrails, wall mounted furniture, you name it.  These things just work.

Toggles are probably fine with newer lighter flat panels, but I wouldnt (and didn't) trust them when mounting my beast of a 50" panel in a plaster wall back in 2008 when that TV was as expensive as a used Civic.

There is just something about the rigidity of lag screws that really is comforting, especially if you have small children that play around/near a heavy and pointy object.  

My go-to method for finding a stud, if there is an outlet near by, is pull the outlet cover and the outlet from the box, see what side the box is nailed to, find the stud that way, and start measuring.  Never had an issue, unlike my attempts with electronic or magnetic stud finders.  They always seem to go off when I am holding them, whether or not I am near where I want to be in the house.  

In reply to 93gsxturbo :

I disagree about the toggles.

Those strap toggles shown above can be rated for over 500 lbs each in drywall, over 2000 lbs each in concrete block.  (Somewhere between those for plaster).  I routinely use them to install handicapped grab bars in drywall where blocking has been forgotten.  A handicapped grab bar needs to be able to resist a 300 lb man falling down with his full weight.  Those can.  

Your 50" panel doesn't weigh anywhere near that.

Old fashioned method has worked for me.

Tap along the all with a finger, knuckle works best,  no stud you will get a hollow sound ,stud gives a more solid sound.   You will need to practice as there is not a lot of difference.

Wally said:

I usually drill 16-20 holes and eventually hit one.

With drywall a carpenter showed me a trick once - you take a small trim nail and hammer it in just above the floor trim looking for the stud.  That way you can put a bunch of holes in and chances are nobody will see them.  My first house was plaster - good luck.

SVreX said:

In reply to 93gsxturbo :

I disagree about the toggles.

Those strap toggles shown above can be rated for over 500 lbs each in drywall, over 2000 lbs each in concrete block.  (Somewhere between those for plaster).  I routinely use them to install handicapped grab bars in drywall where blocking has been forgotten.  A handicapped grab bar needs to be able to resist a 300 lb man falling down with his full weight.  Those can.  

Your 50" panel doesn't weigh anywhere near that.

I was going to say the same thing. We install stair rails with these things sometimes. The television is going to break in half before they pull out of plaster assuming it's in good shape and you install enough. (4-6 of them)

SVreX said:

In reply to aircooled :

Plaster walls are rarely on 16" centers. Often, they are very odd. The overall distance divided evenly by however many studs they had. 

Having grown up in very old houses it seems that 16” centers were like Bigfoot.  People claim they exist but I don’t know anyone that’s seen one.

this post is very timely for me.  I just got a new space and want to mount a fairly new 50" flat screen on a drywall wall.  Looking at the chair rail for nails is a good idea that I will try to use.

Looking for nails in the woodwork is one of the best methods with plaster walls.  It doesn't always work with drywall. 

Most modern houses have trim that was installed with air nailers. An air nailer doesn't care if you hit the stud or not, it will still set the nail. It won't hold as well, but many carpenters don't care. 

Older houses were assembled with hammers and nails. You can't drive a nail (and set it) into a plaster wall with a hammer.  You have to hit a stud. 

...and stacked trim is almost a dead give away. If the baseboard, base cap, shoe molding, chair rail, and crown molding ALL have nail holes that align with each other, I guarantee the stud is there. 

(I threw away my stud finders years ago)

Wally said:

SVreX said:

In reply to aircooled :

Plaster walls are rarely on 16" centers. Often, they are very odd. The overall distance divided evenly by however many studs they had. 

Having grown up in very old houses it seems that 16” centers were like Bigfoot.  People claim they exist but I don’t know anyone that’s seen one.

16" centers are a by-product of panel wall finishes (i.e.: Sheetrock, paneling, etc) that come is 48" widths. 

There was never any reason for plaster finish walls to be built on 16" centers, or ANY center. 

Know anyone with a thermal imager?  Even a basic one should work.

I've owned two houses with plaster walls and both had studs on 16" centers. One 1928, one 1954 construction. The 1954 house had gypsum lathe so that makes sense.