Or maybe vice versa would make more sense as that would imply that the sheetrock is new and the lath and plaster old (duhhh).

Nice house in Marin, I'm guessing 20s or 30s - lath and plaster - studs are 3.75 x 2 - knob and tube wiring. I'm knocking out one wall to merge the master bedroom in Unit A with the bedroom in Unit B. This is about the nicest 2 unit house I've ever seen, not a duplex - unit A is a deluxe 2 bedroom while unit B is a deluxe studio.

I'll have to heal over the stub where the old wall and ceiling were and I damn sure don't want to shorten an apprenticeship at lath and plaster from 2 years to 3 days.

My first instinct is to use paper and hot mud over the joint tween the plaster and the rock, and sand and re-coat like I was enjoying myself.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K