Plasterboard Inside Corners

[Mike Lamb]

Plaster walls in 1950s-60s homes around here are typically applied on plasterboard, not lath. I've only recently noticed very high moisture readings at most inside corners (not all) of these houses with my Protimeter so I assume it's not moisture underneath but metal.

Is anyone familiar with plasterboard plaster jobs? Did they use metal inside corners?

[Bill Kibbel]

You are correct. It's not unique to plaster on gypsum lath though. It was being used by the early '20s with plaster on wood lath as well.

The common (brand) name is Cornerite. It was applied to inside corners of walls and at wall-to-ceiling joints. It was used because of the constant cracks at these joints when Portland based cement plaster replaced lime-based plaster

I think I have a pic of it somewhere...

[Bill Kibbel]

Click to Enlarge

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[ericwlewis]

and it's a real pain to remove when gutting a room. The only worse thing to remove from a wall that I've come across is the expanded metal nailed to the wall behind tile tub surrounds of the same era. It's usually nailed really well and infused with a thick mortar bed[:-irked]