Hi all - I've seen some info on this site about "extruded chipboard core doors". Basically, from what I understand, fire doors with holes running through them, making them light. I've has a query on some doors that were "too light" to be considered fire doors from the assessor. Almost all are unmarked but are 44mm thick. A couple of the doors in the same building have plugs, indicating they are fire doors, but the vast majority don't. As a curious person I armed myself with a screwdriver and took off the locks from both a marked and an unmarked door and they looked identical inside. The have a chipboard infill with hollow cores running through Doors were probably put in the the late 90s - was this a thing back then. I dont want a whole heap of residents to have to pay for doors to be changed when actually, there doors were a thing back then (perhaps even are still?). Also none of the locks (marked nor unmarked doors) has intu paper on the lock keep - does this make a huge difference on these types of door (service cupboards in resi) up to 6 floors. All doors, even the even the "proper" fire door with a plug had unmarked hinges... previous FRAs have not made any comment on this so I'm wondering if these types of doors have fallen into disrepute?