wrote:
I have a very old (100+ years) house, and am having issues with the lathe
and plaster ceiling in one of the bedrooms. The plaster has started to
sag and is causing some cracking. The cracks are all hairline, except
for the spot where all the cracks are forming from, which is a hole about
1/8-1/4 of an inch wide.

Issue doesn't appear to be water damage related, but just from age/house settling.

After doing some research into the issue, it seems that my best course
of action would be to put some screws into the ceiling to secure the
plaster and then patch over it. I do have some additional questions:


1)Even though this is caused by loose ceiling, would i still need to
score the cracks, and if so how deep will I want to go?

2)Do I need to score, secure, and patch all in the same day, or is this a
process that I can break up over 4-5 days?

3) Once I'm ready to patch, should I get some mesh to put down after the
first layer of patching?

4) What kind of patching agent should I use? I've seen DIY articles
recommend anything from all purpose bonding agent up to durabond.

5) Should I screw all along the cracks, or just where I feel loose ceiling?

Thank you all in advance!

When my son had some serious sagging and cracking (caused by a roof leak)
we reattached the sagging plaster using plaster washers similar to these:

https://www.google.com/search?q=plaster%20washers

In our case the damage also required the replacement of some sections with
drywall patches. After looking at the semi-finished job and the amount of
skim coating it would have required to hide all of the washers and seams,
we opted to add a layer of drywall over the entire ceiling and mudding the
two seams in the field and the wall/ceiling junctions. It came out real
nice and no more worries about future cracks.