Confusing but the answer is simple.
Hight requireme mount smoke detector from ceiling on wall.
Place a smoke detector about 12 inches from the ceiling on the wall.
Every new dwelling shall be provided with smoke detectors.
If you have ceilings that are pitched install the alarm within 3 feet of the peak but not within the apex of the peak four inches down from the peak.
Mount smoke alarms high on walls or ceilings remember smoke rises.
The detector may be placed on the ceiling.
Because carbon monoxide is slightly lighter than air and also because it may be found with warm rising air detectors should be placed on a wall about 5 feet above the floor.
Ceiling mounted smoke detectors should be mounted at least 6 inches away from where the ceiling meets the wall.
Below is a series of recommended mounting heights for fire alarm system equipment including different types of smoke detector including optical beam detectors and heat detectors.
Clarification is required in nfpa 72 on how to apply smoke detection spacing requirements for these high ceiling applications.
Wall mounted alarms should be installed not more than 12 inches away from the ceiling to the top of the alarm.
Mount the smoke detector on a wall at least 6 inches away from the ceiling but not more than 12 inches away keeping the detector away from the dead zone but high enough to detect the smoke since smoke rises.
The table below also shows heights which detectors are permitted to be mounted at if 10 or less of the ceiling is the height shown.
Wall mounted alarms should be installed not more than 12 inches away from the ceiling to the top of the alarm.
There is inconsistency in design and code enforcement for spacing requirements of smoke detectors when installed in areas with high ceilings where high ceilings are defined as over 10 feet in height.
Mount smoke alarms high on walls or ceilings remember smoke rises.
Do not place the detector right next to or over a fireplace or flame producing appliance.