thermal barriers that may form at the ceiling.  For more details, 
see MOBILE HOME INSTALLATION below.
•  When mounting an alarm on the ceiling, locate it at a minimum 
of 4” (10cm) from the side wall (see figure 1).
•  When mounting the alarm on the wall, use an inside wall with 
the top edge of the alarm at a minimum of 4” (10cm) and a 
maximum of 12” (30.5cm) below the ceiling (see figure 1).
•  Put smoke alarms at both ends of a bedroom hallway or large 
room if the hallway or room is more than 30 ft (9.1 m) long.
•  Install Smoke Alarms on sloped, peaked or cathedral ceilings 
at or within 3 ft (0.9m) of the highest point (measured hori-
zontally). NFPA 72 states: “Smoke alarms in rooms with ceiling 
slopes greater than 1 ft in 8 ft (.3m in 2.4m) horizontally shall 
be located on the high side of the room.” NFPA 72 states: “A 
row of alarms shall be spaced and located within 3 ft (0.9m) of 
the peak of the ceiling measured horizontally” (see figure 3). 
MOBILE HOME INSTALLATION
Modern mobile homes have been designed and built to be energy 
efficient.  Install smoke alarms as recommended above (refer to 
RECOMMENDED LOCATIONS and figures 1 and 2).
FIGURE 2
FIGURE 3
FIGURE 1
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