I moved into an old (c. 1920s) rental apartment building in the northeastern US (Philadelphia) and would like to hang pictures and secure some furniture.
I tried putting nails in several places around the house, on internal and shared walls, but the nails only go about 0.5" deep into the plaster (I cannot find any studs). There seems to be a hard surface behind that spot. I had no such issues with external walls.
What material is most likely to be found around 0.5" into the wall?
If the wall has studs they could be yellow pine which "turns to stone" when the wood dries. Try to drill very small pilot holes to see if is wood or something else.
I think it was the mixture of stone in concrete or maybe something like river stone. and your external wall are made from ordinary brick, easy to nails, no strength needed. Maybe you need black nail (made from steel, tougher than white) or you can drill first if you have one. You can also try it with a bolt (with drill machine), no hammering needed, it can also easier to remove.
Use a beating-drill with a 'widiam' tip, a regular metal/wood and regular (not beating) drill tip won't be effective in concrete or bricks walls.
Then, instead of nail, put fisher wall plugs with appropriate hook. For a light stuff 4mm or ensuring stuff to the wall is enough, if you have to put up something heavier (like a big mirror), 5 or 6mm will be better.
I don't know if there in US have mm-sized fisher, but you can easily convert to nearest US-measure. 5mm is about 1/5 inch. For 'general purpose' suggest to buy some 5mm taps that is not too big for a picture and is strong enough to hold a heavy mirror.
If you want to figure out if it's a drywall or a brick one joust knock it, if it 'sounds empty' it's a drywall.
