I just moved in to a new apartment, in a very old house. The landlord mentioned that it is over 100 years old. The walls are plaster, which means (to the best of my knowledge) that there is lath beneath the plaster.
On most of the walls, I've been able to hang things without much trouble. My stud finder has a little trouble on lath, but I've been able to get by, mostly because I'm not hanging lots of heavy stuff.
However, I've run into a problem on one wall. It is an exterior wall. My stud finder fails completely here. The picture I'm hanging is heavy, but not terribly heavy, so in the absence of a stud location, I figured I would be fine if I could get a relatively deep nail in or some sort of anchor and screw.
However, when I drove a nail in, it hits something very hard, and the nail will not go any deeper. It gets less than an inch into the wall, probably closer to 0.5". The plaster is very crumbly, and I don't trust the plaster to hold the picture I want to hang with such shallow penetration.
What can I do? What am I hitting behind this wall, and what is the right way to hang something here?