I use to have an large commercial Insurance and mortgage inspection business in the south, prior to selling it (this was after I left the org) I completed a few inspections on kingdom halls from that Era.
Two were turned into banks, one a daycare, and one that I can remember a pharmacy. They all obviously passed the local inspection, which honestly does t require much but that didn't mean they quality of work and materials were the best.
As I remember, they all had mold problems in the exact same area in the men's restrooms around the urinals.
Water intrusion from piss poor roofing, and cheap roofing materials. The landscaping practicing led to termite issues due to packing mulch directly up against the building and moisture problems from putting shrubs directly up against the building.
Cheap materials are generally used for obvious reasons. The older halls however tended to be the exact opposite. You would see that alot of care was put into the construction of those older buildings