Fire Alarm smoke detectors on walls not ceiling

[Great_scot_selfbuild]

Upstairs we need to install smoke detectors on the walls as there is no service void in the ceiling. We have a small area of the flat ceiling as the first floor is mostly in the pitched roof space, so fitting the detectors to the top of the vertical wall would be in the space where smoke would gather first anyway. Has anyone done this and achieved BR sign off?

 

[JohnMo]

What do the manufacturers install instructions say? You can always install 10 year battery version of the detector, then you need no services 

[Great_scot_selfbuild]

59 minutes ago, JohnMo said:

What do the manufacturers install instructions say? You can always install 10 year battery version of the detector, then you need no services 

BR requires a mains powered fire alarm with battery backup