How do I replace a screened-off area of a plaster/lathe wall near sheetrock?
Cut a piece of sheetrock the size of the patch you need. Then place it over the hole and carve around the outside with a pencil. This will give you an exact size to cut for the patch. You will own to screw wood behind the edges for backing. Screw within the sheetrock patch and use mesh tape to cover the joints. Using a setting compound such as durabond to mud the joint will save drying time as it sets faster than premix compound.
if its possible I would cover the entire wall with Sheetrock using screw long enough to grab onto the lathe at the back the plaster then finish it in the regular method i find this to be easier then trying to blend the drywall patch to the plaster.
i tear the plaster and the lath out. then you will find that the wall is probably thicker next the drywall you want to put on. find out the difference and normally its a 1/4". i rip down strips and nail them on to the studs consequently add my drywall. plaster walls usually are about 3/4" gooey back to the stud.