Plaster walls? Is it plaster? Lots of ?s

UVAjenny said:

We just moved into a home built around the 1950s. The walls appear to be plaster (all brick exterior). The home has been recently remodeled/upgraded but there are a few things we want to do like hang floating shelves, anchor bookcases in my toddler's room, etc.

We went by the local hardware store and asked about screws/anchors. They hold use to drill holes and then use concrete screws. Well, everytime we do that (using the drill bit provided to us at the hardware store), the screws simply come out of the wall and we're left with gritty dust on the floor and the holes get bigger and uglier.

We've tried this twice now, any ideas on what's going on? What can we do? Thanks!

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Although it was not the best and most approved way of building a "lathed plaster" wall, most plastered interior walls during that era were built by nailing onto the wall studs, strips of wood called "lath strips", perpendicular to those studs. These horizontal strips were usually spaced anywhere from one foot to 16" apart. To these strips, hard fiber boards were often fastened. Usually about 1/2" to 5/8" thick.

Fastened to that flat surface was often an extruded wire sheet of screening that the plaster was "wiped" into for holding strength. (But not always... sometimes the plaster was applied directly to the fiber board.) Then, when that base coat of plaster set up, they proceeded to trowel on the decorative finished coats of plaster.

Now, sometimes the hard fiber board was omitted, and a paper-backed wire sheet was stapled directly to the lath strips. An even cheaper method was sometimes used. The lath strips would be left out altogether, and the paper-backed wire sheets would just be attached right to the studs. Yes, sometimes the wire didn't even have a paper backing...... not necessarily a bad thing, but it took skill to properly apply plaster to non-backed wire lath, and a lot of plaster could be wasted.

If you got lucky, and they did the job right, (for those days), there will be no wire, and the lath strips will be almost solidly covering the walls. Very easy to find screw purchase this way. But it sounds like your walls might not have been treated to the full, solid lath strip method.

So... you can see that what you want to do is to try and locate either the lath strips (if they are there) or the studs (they WILL be there). If you screw into these wooden parts, your assembly probably won't pull out.

You can locate these pieces of wood by drilling sample holes with a very small diameter masonry drill bit till you feel comfortable that you are actually drilling into some solid wood.... you should see wood shavings coming out as the drill bit turns.

It's a bit of a PITA to locate the necessary wood backers this way, but it's about the only way to do it. Otherwise, you're just drilling into crumbly plaster which will simply continue to wallow out as you are now experiencing.