How do I find a stud in Lath wall thicker than 1.5"?

Hi there,

I purchased and returned just about all the mainstream stud finders because I'm trying to mount a 42" TV on the wall. I thought this was going to be a simple enough project... find the stud, drill a few holes, insert anchors, screw in wall mount, done right?

For some reason my stud finders tell me there is a stud's edge all over the entire wall. So I drilled a hole on one side of the electric receptacle where my stud finder couldn't detect any electrical current. A lot of black/greyish dust came out of the wall no wood chips at all. I basically drill out 2" of black powder and this lath stuff is nothing that I would feel comfortable mounting an expensive TV in.

I live on the ground floor of a three apartment house built in the 50's. Copper pipes, poor insulation and all. On the other side of the wall I want to mount this TV on, happens to be the stairwell wall heading up the upper floor. I figure there must be some weight bearing studs in there somewhere because I'm between the basement and the upper floor.

Any suggestions?

Thanks

 

You can insert a wire through a gap around an outlet box or through the hole you've already drilled and feel for the joist. This works best on hollow interior walls. On exterior or insulated walls a stiff steel rod like a piece from a clothes hanger will be stiff enough to push through the insulation.

You can also remove the base molding and drill a series of holes where they will be concealed by the molding. Keep drilling holes about 1 1/4" apart in a line until you find a stud.

 

If this is framed with wood studs use a small masonry bit. It will drill through the plaster but not easily through the stud. So when you hit the stud you will know, Keep trying until you find the first stud then 16" left and right should be the next one. Do the same test to make sure you hit the stud.

Now, if this is an apartment house it might be built more along commercial lines. If this happens to be the case then the lath could be expanded metal lath and the studs could be any of several kinds of very narrow pieces of steel like miniature bar joists or 3/4" cold rolled channels. They have the strength to hold your mount but are going to be hard to find and hit.

If you are bringing black dust maybe you are drilling through plaster over concrete masonry units. If this is the case they should hold well if you use molly screws or toggle bolts.

 

There should be a stud next to the outlets, find one and work away from it when checking.
It was common years ago to use 24" O/C not 16".
Another way is to look for nails in the base board.

 

There is probably some kind of fire resistant material in the wall. Maybe sound proofing as well. I don't know what the codes were for fire separation in stairwells when the house was built. I am still holding out for masonry. Or how hard does it drill? Maybe it's poured concrete. Or it could be conventional framing and the black stuff you are bringing out with the bit could be rock wool insulation.

PLEASE tell us what you find.

 

I have had very good luck with this: CH Hanson 03040 Magnetic Stud Finder - Amazon.com No batteries, it uses rare earth magnets to fine nails and screws. On plaster walls you have to use a light hand but it does find the nails.

BTW- Welcome to the forums!

 

If a house of this vintage is conventional construction it is odd that the plaster is 1.5" thick. Even the gypsum plaster and gypsum lath don't normally add up to that thickness. If it is either gypsum or Portland cement plaster over metal lath it might seem to be 1.5" thick. Does your drill go all the way into the void behind the plaster? Does your drill reach to the limit of the length of the bit before you hit a void? Or do you hit something harder than the plaster after 1.5"? If this is frame construction then some of the ideas about pulling off the base board and looking for nails of drilling for the stud or fishing beside an outlet box will work. Once you get the first stud the rest should be easier to find.
BUT if I am right about this being metal lath over a steel framing system the targets are steel and only 3/4" wide in one system and only 1/4 - 5/6" with another system and those are round. But if you could find them and hit them with the right anchor they would hold.

My curiosity is up on this one. Please let us know.

 

I am about to go crazy wanting to know what you found inside the wall. Please tell us if you found wood studs, some kind of steel framing system, masonry, poured concrete, or what and tell us how you mounted the TV.

 

I think I would be buying a stud finder,if you hit a hotwire with the bit, prayers wont' help.

 

Still no word on what was inside the wall or how it was built.

 

strange that he started this thread but we haven't heard from him since. Maybe the house was built by gangsters and they filled the walls with cash instead of newspaper. I think the "R" value of US currency beat that of the NY Times; at least it did back then. Now they're both useless.
Ba-doom!

 

I can think of a lot of ways this wall could have been built that correspond to what the OP found with his drill.
Interestingly, last spring I helped a poster here who was from Canada and in the same business. We corresponded a lot then he just dropped out. Though he did at least thank me.

 

Notsohandy:S

If you see this message please please tell us what you found.
Was it plaster over metal lath?
Was it plaster over masonry of some kind?
What were the studs?

We gave you a lot of good advice.
Please let us know how we did if not that it matters to you, for future reference for us.

 

You may want to try a PM, since he isn't monitoring the forums. At least it will show up on his email notifications.