A ceiling collapse in an old Boise apartment building made me rethink my whole approach to patching.

I was helping a buddy fix a small water stain on a ceiling in a place built in the 1920s. The plaster was rock hard, so I just feathered some mud over it and called it good. Two days later, the whole eight-foot section came down in the middle of the night, right onto the tenant's bed. Luckily no one was hurt. The problem was the old plaster had completely lost its key to the lath behind it. My patch held, but it pulled the whole rotten ceiling down with it. Now I won't touch an old plaster repair without first tapping every single square inch to check for hollow spots. If it sounds loose, I cut it all out back to solid material and put up new board. It's more work, but how can you sleep at night otherwise? Has anyone found a good way to test old plaster without making a million holes?

2 comments

2 Comments

the_barbara23d ago

Tapping is a good start but it can miss smaller delaminated spots. A thermal camera rental can show hidden moisture or voids behind the plaster without any damage. It's a bit of an upfront cost but totally worth it for peace of mind on a big job.

craig.tyler23d ago

Yeah the "peace of mind on a big job" part is what got me. I always thought thermal cameras were overkill until I rented one for my own plaster project last year. @the_barbara is right, it showed a bunch of tiny soft spots my tapping totally missed. Changed my whole approach.