It's pretty simple to find a stud in common drywall. ... Plaster can be too thick or dense to find a stud with common stud finders, which is probably why you're finding that these don't work. And if the lath is a metal wire type, instead of older wood lath, a stud finder will produce false readings.

How do you hang things on plaster walls?

Screws (and screws with masonry anchors for heavy items) are your best choice for hanging things on plaster walls without picture rail. For lighter items, simply screwing into the plaster with a 1 1/4” drywall screw is usually enough to get the job done.

What is usually behind plaster walls?

Rock Lath and Plaster

Rock lath was used to build many plaster walls between 1900 and 1960. Unlike wood lath, which is applied in strips, rock lath is a sheet of rock with holes that's been chemically treated to allow for wet plaster application.