There are many horror stories on collecting for damages from OTAs including a current thread on BP where guest left doors and windows open upon exit that resulted in frozen pipes.  

Quote from @Chris Olandese: Stop expecting her to respond.Post a notice on her door and take a picture of it for evidence.

The roof is over the next door properties property line.

Either his flipper going for foreclosure, or as lender, his LTV is rising to above 100%.

It is usually much easier to seal a existing door way then it is to move walls in my experience. 

Egress: Two methods of egress, typically a door and a window.Ceiling height: At least half of the room should have a ceiling height of 7 feet.

First off- $4.5M for 48 units and 50% are vacant is not a steal, unless this property is located in a downtown area and you have a contact with a developer who will pay 2X to build a high rise. $93k/unit for 50% vacancy doesn't carry hardly any debt, hence why they are capping you at $500k.

There can also be chemicals in the treated lumber that are harmful to the environment.Invest in a good screen or built in door system.  

Rising home prices for developers isn't new, but if you were in contract, what they did is most likely illegal.

Real estate is local.The value is just fine here, as it is one of the most desired locations in the Côte d'Azur, and being next door to Monaco, which is one of the wealthiest places on the planet.