In a crawlspace I wouldn’t call it a fire wall as much as I would call it a security barrier.
I lived in a townhouse that the cable company ran their cable through the attic from unit to unit. When they did the install they took out the block firewall so they can run the cable without having to go through the houses. They not only created a fire hazard, but you could go into your neighbors attic and gain access to their home. I fixed my attic, but others didn’t.
I did some inspections on bldgs to confirm the firewalls were not damaged after a fire caused by a non-grounded ceiling fan, that happened to be the bldg president’s unit, destroyed the place.
*It started when an old ceiling fan caught fire in a Ventnor B apartment. *
The flames raced through the crawl space and through holes in the firewall destroying half the homes in the building. The holes were made by workers installing cable for Adelphia Communications Company. “They were big enough to walk through,” Adam said. Fire experts say the holes are worse than having no firewalls at all because they create a back draft that channels smoke and flames.
I always write these up as a safety/security issue. I lived in an apartment once where all the attics in my building connected and when I came home one day my attic was open due to the neighbors kids.
Definitely report it so your client can make their own decision on how to move forward.
A few years back there was a case where a lady was attacked and raped in her own home. She lived in a home that had been converted into a duplex. Her attacker lived in the other unit and gained access through trap door access panel. Both units had trap door access panels.
I’ve not inspected any duplexes yet but I definitely will report the issue if I come across it.