Patching a Leak in the Ceiling Wall
I am not a plumber. But I know when they want to access a ceiling leak. I cut this hole for the plumber of my client and then fixed new sheetrock, plastered and sanded like new. A job like this takes several visits: around 30min to cut out and re-block and then less than 15min after to plaster/skim/sand for a couple of days.
Plumbers need to make holes in walls to find leaks but they hate fixing them .
Good thing I like doing the reverse.

