In a Philadelphia-area house built in the early 1950s: I cut out a piece of wall to fit an old work box. The piece I removed is shown below. The original walls were finished in plaster, but I can't understand what I'm seeing here: There's half an inch of plaster on top of what appears to be a modern-style half-inch paper-faced gypsum panel! Is this consistent with known plaster wall construction from that era? If so, what is it called, what does it consist of, and how was it done?
(Exposed, painted face of wall on left:)
(The house has gone through various renovations over the years, so there are places where walls are just modern sheetrock. But I can't imagine somebody putting up gypsum and then plastering over it!)
Best Answer
What you see there is a hybrid gypsum/plaster from the 1950s. It represents a transitional stage between traditional wood lath and plaster to modern drywall techniques. You'll probably find metal lath at inside corners and metal corner bead at outside corners and door openings. The gypsum panels are 18 or 24" high.
I owned a home with exactly that in it for 17 years and consider it to be the best wall treatment ever devised due to its strength and durability, along with the fact that it can be easily cut to, say, add an electrical outlet.