How to hang a TV on a drywall with no studs and no room for toggle bolts?

Question

I am hanging a TV in a narrow wall space that has no studs behind it. I have verified there are no studs behind the drywall by using two different stud finders (a cheaper and a more expensive model). Both devices did go off once, but only in a small area in the middle of the wall, not along the whole height, so it's definitely not a stud.

This TV mount requires 4 screws. The original plan was to use 4 toggle bolts (a.k.a. drywall screws). However, after pre-drilling the holes, I found that there is another hard surface that begins about 1.5 inches after the drywall. There is no room for the "butterfly" part of the toggle bolt to open up. I don't know what the hard surface is. When I give it a knock with a screwdriver, it sounds like either metal or brick. This is an apartment building over 100 years old. There is another person's apartment behind the wall. A few questions:

1) Should I do additional testing to find out if that surface is brick or metal? If so, how?

2) If not, should I assume it's brick and proceed with trying to put the screws into the brick, either directly or with anchors? What kind of additional gear would this require? Special screws, drill bits, anchors?

3) Alternatively, should I stick with the toggle bolt method, which would require drilling large openings in the second surface to allow for sufficient clearance for the toggle bolts to open? Not sure how easy this would be.

Thanks!

Answer 1

An over-100-year-old apartment building is likely plaster-over-lath. In that case, you should be able to drill through the plaster and into the lath to sink wood screws. If this is so, you'll see what looks like sawdust on the tip of the drill when you pull it out. I'd probably use a bunch more than just the 4 recommended, but it'll hold a TV under 50 lbs.

If you want to find out what's behind there, just try to drill it (with a drill bit you don't care about). If the tip comes back red and chewed up, congrats, it's brick, and you can sink masonry anchors if you want complete overkill. You'd need to drill with a masonry bit, and then you can choose either expanding anchors or epoxying in something more like a drywall anchor.

This ain't a job for toggle bolts, though.

Answer 2

As Joe points out, if this wall is original, then it's not drywall, but plaster. You can't easily detect studs behind plaster walls with a stud detector. You likely have to use test holes. One option is to drill a largish hole in the center(ish) of where you will mount the TV. Then use a coat hanger to fish it into the hole to see if you can locate the studs on each side.

If it's a solid wall (brick, likely) then that gets trickier, Old brick and mortar isn't that strong in terms of ability to hold screws. But you can try it by drilling into the mortar and using masonry screws.

Finally, if this is a shared wall with the neighbor, first check your tenant agreement to see if you are even allowed to mount a TV to it. Lots of apartments will have restrictions on what you can hang on shared walls--both for fire code issues (they don't like holes in party walls) but also for common courtesy of trying to avoid noise transference.

Answer 3

I mounted a TV on a party wall in my townhouse. As best I could determine, wall construction was masonry block fire break with 2x2 (more or less) strapping to carry the drywall and create a narrow space for wiring.

I didn't want to rely on the strapping to hold the bolts, so used masonry anchors. I chose to use a stud-type anchor. I located the 2x2s and drilled through them so that they would take up the compressive load as the anchor bolts were tightened and not risk deforming/cracking the drywall or buckling the mount. I think the final result could have supported the weight of a car, so the 40lb mount + 80lb TV was quite secure.