The affected area looks to be roughly 10 feet in diameter. There are a few small yellowed spots and some bubbling on the surface, mostly on the 'fault lines'. I'm sure most of the cracks were there to start with (like hairline fractures in any 40-yr old plaster ceiling), but the water damage has accentuated them. I have no idea if the plaster has separated at all from the lath.
Now, regardless of the fix, the HVAC guy is paying for the job. I just want to know what the best solution is for the long term life of the ceiling. I've considered just sanding/painting, have gotten advice to put drywall over the entire ceiling, and advice to tear out the damaged section and re-plaster it.
Any thoughts? Thanks.