What kind of wall do I have, and do I need anchors?

Question

I have a 36"x60" 30 lbs frameless mirror that I want to hang up on my wall, but I can't seem to find the studs! I've tried using a magnetic stud finder with no luck. I've drilled multiple holes in my wall and here is what I found:

• There's an outlet at the bottom right edge of my wall. I drilled one hole at eye level about 9" to the left of that and did hit wood! I thought I found a stud, but then I drilled another hole closer to the floor where the base of the mirror would be. It's directly underneath the first hole but now there's no wood! I'm so confused.
• I drilled a bunch of holes elsewhere in the wall, but no wood. All of these holes are pretty deep, like 1 1/2". Is my wall not hollow?
• Shining a flashlight into some of these holes makes me think it's not made of drywall? Could it be concrete?
• Also, with every hole, I seem to have drilled through some sort of metal fence thing about 7/8" from the surface. Is there like a metal mesh inside my wall?

The surface of my wall is textured and I live in an old apartment in San Francisco (I have rent control so it was probably built before 1979).

I've given up looking for a stud and just use wall anchors instead, but it doesn't look like my wall is hollow so the anchors probably won't even come out the other side. What kind of wall do I have, and given the thickness, can I just use the screws by themselves to hang up the mirror?

Answer 1

I would use expanding plastic screw anchors or wooden dowels.

I've used solid wall anchors such as this many times over the years and they provide secure attachment when installed properly. You need to drill a clean, precisely-sized hole in the wall to hold the anchor. The size/depth of the hole is specific to the anchor.

When a screw is introduced into the anchor, the screw causes the anchor to expand and compress against the inside diameter of the hole enough to provide a strong connection.

This is just one example, there are many variations on this. For example, to use the anchor pictured, you need to drill a 1/4" hole 1" deep and insert the anchor. Then use a #12 or #14 screw. These would provide plenty of holding power for a 30# mirror assuming you used a few anchors to support it and prevent any movement of the mirror, etc.

Another alternative would be to use a short piece of similar diameter wood dowel in the same manner. I do think the plastic anchors work better than dowels, but I only have anecdotal evidence to support this. On the other hand, I've seen dowels in used and they seem to have been perfectly secure in situations similar to yours for many, many years.

Answer 2

For a 30 pound mirror i would not use just screws into plaster and lath.

If your wall is as you state in the comments then i would use My favorite Toggle anchors

They are very strong and have a beefy machine screw.

You will need a 1/2 inch drill bit. You drill the hole, collapse the anchor, slide it into the hole, snug up the wall tab and break off the excessive part of the tabs, then just thread in the machine screw.

There needs to be enough room in the cavity of the wall for the anchor to go in and make its turn.

If your wall is plaster and lath there is a possibility that the back side where the toggle will be sitting against is not flat, this would cause the toggle to not be straight and aligning the screw to thread in may be problematic.

Here is short but informative video on how to install.