Odd discrepancy in fire engineer's report

[Adsibob]

As our ground floor is very open plan and we wanted a sprinkler system instead of a fire door, we've had to get a fire engineering report to sign off on the sprinkler system. All a bit silly imo as the sprinkler system we are getting is from imist and they comply with the regs, so not sure why we need to fork out £1k for a fire engineer to confirm, but hey ho.

The fire engineer's report has a summary of the recommendations at the beginning of her report which says:

 

"installation of single unified automatic fire detection and alarm system (LD1, minimum Grade D2) throughout all parts of the dwellinghouse with simultaneous evacuation of all floors on occurrence of alarm i.e.; detection to be provided in all habitable rooms, interlinked and mains powered."

 

The report includes some mark ups of my floor plans which show no less than 12 smoke detectors and 2 heat detectors. Weirdly, she has included smoke detectors in the MVHR room and in the top floor hallway, even though a hallway is not "a habitable room". I had understood that the definition of a habitable room for these purposes are

 

 any room where individuals will sit or lie down and require a reasonably quiet environment in which to concentrate or rest.

 

Can anyone reconcile this apparent inconsistency? Will building regs spot that I have not put a smoke alarm on the second floor (top) landing? We've already plastered the ceiling there and painted it, so I think it's going to be tricky to fit it now as it needs to be connected to the mains. I also don't see the need to have a smoke detector on the top floor landing as the two rooms on that floor, as well as the MVHR room and the attic space will have a detector each, so there is already 4 detectors on that floor anyway.