On Wed, 8 Apr 2020 16:18:14 -0400, Hawk wrote:

On 4/8/2020 12:17 PM, Terry Coombs wrote:
On 4/8/2020 10:14 AM, dj wrote:
I have a big hole in the ceiling of my living room caused by a leaky
roof. I
think we have fixed the leak and want to do at least an "average" job of
fixing it myself.
If the leak is actually fixed, I do it right. At this point, I don't know
where to start, besides knocking down all the loose plaster. Please
remember,
this house was built in 1922,
and frankly, I don't even know what the "cement like" surface is in the
middle. This is the ceiling between my first and second floors. Do I
just use
spackle? patching plaster" or what
to start with.
https://www.homeownershub.com/img/m2



* Peel all the loose plaster from the cement like surface , then spray
the substrate with a 50/50 mixture of Titebond II and water to bind the
surface . When that's dried a couple of days trowel on a layer of either
premixed drywall mud or (preferred) use a dry mix quick setting drywall
compound - 90 minute probably if you have no experience . Build the area
up flush with the rest of the plaster one THIN layer at a time .


Exactly how I would approach.
That works if the base plaster has not all gotten soggy and fallen
out. I had to do it "my" way when a roughly 15 square inch "hole"
turned into over 96 square feet of soft soggy gyp-roc lath spanning
from the kitchen to the dining room in friend's house last year.
Instead of blocking to hight we installed 2 layers of drywall - one
screwed every 8 inches and the other glued and screwed every 18 inches
staggering the joints. The 2 layers were chosen to match the thickness
of the old plaster - 5/8" screwed on and 1/2 inch glued over top.