Behind Wood Lath Plaster
Here's what a wood lath
and plaster wall looks like, after one side had been removed. I don't
know exactly when they stopped using wood lath, but I would guess it to
be around the 1930s.
The wood lath, is usually about 3/8 of an inch thick and an inch and a half wide and was nailed onto the wall framing and then a plaster mixture, was applied over the wood lath.
The plaster would then be smoothed out, to form a reasonably flat wall. It was still going to be quite a while, until drywall was going to take the place of wood lath and plaster home finishes.
The next time someone asks you about wood lath plaster, now you have a pretty good idea, what it looks like, from behind.