Carpeting is awful, flooring is awful, drop ceiling is awful.

Apparently there is a small leak of water coming through ceiling behind kitchen cabinets into his unit from my unit above.

My floor system is 1.5" and ceiling height is 10', so 11.5' total.

I'd look for cracking drywall upstairs and in the ceiling and walls beneath the affected areas.

I've added value to the property by painting, replacing light fixtures, multiple ceiling repairs, shower repair, replaced toilets and vanities, replaced wood rotten side door with glass door, demolished an old shed to create more yard space, a/c repair, Heat repair and more .

Has heat & air, finished walls, ceilings and floors.

Include the ceiling too.

The one picture looked like previous leak in ceiling but it could just be the picture quality.

One of the biggest reasons he recommended this is to preserve ceiling height in the basement which is already a bit shorter than I'd like.

It will fit the requirements of separate electrical meters, separate sewer connections, distinct shutoffs (electric and plumbing), independent HVAC, 5/8" Type  X ceiling sheetrock (whatever that inspection entails), meeting egress requirements, etc.