Potter Fire Alarm Systems - Manual (Page 18)

16
Fire Alarm Training • 8700055 • Rev F • 4/10
Beamed Ceilings
Flat Ceilings
A. For ceiling heights of 12 feet or less and beam depths of 2 feet or less:
Use smooth ceiling spacings running in the direction of the beams, and 1/2 the smooth ceiling spacing for the direction
perpendicular to the beams. Spot type detectors may be installed either on the ceiling or on the bottom of the beams. NFPA 72
2007, 5.7.3.2.4.3
B. For ceilings higher than 12 feet or beams extending down more than 2 feet, spot type detectors shall be located on the ceiling
in every beam pocket.
NFPA 72 2007, 5.7.3.2.4.2
See NFPA72 2007, 5.7.3.2.4.3 for sloped ceilings with beams.
Sloped/Peaked Ceilings
Sloped Ceiling - Having a slope of more than 1.5 inches per foot
Peaked Ceiling - Having a slope of more than 1.5 inches per foot in two directions from it’s highest point. May include domed or curved ceilings.
To determine if a ceiling is sloped or peaked:
Divide the difference between the height of the low wall and the highest point of the ceiling in inches by the width of the building
in feet. If the answer is 1.5 or less, the ceiling is considered flat.( Highest point of ceiling in inches) minus (top of low wall in
inches) divided by (width of building in feet)
Smoke and heat detector placement on sloped ceilings:
Make all measurements parallel to the floor, not along the ceiling.
Locate the point on the ceiling which is 3 ft. from the high sidewall. Locate the first detector anywhere within that three feet,
except the four inches nearest the wall. The remaining detectors shall be located in the remaining ares on the basis of the
horizontal projection of the ceiling, spaced in accordance with the type of construction.
Smoke and heat detector placement on peaked ceilings:
Measure three feet horizontally from the peak in both directions. Follow the guidelines for sloped ceilings.
USE SMOOTH
CEILING
SPACING
2’ OR LESS
USE 1/2 SELECTED SPACING
BETWEEN BEAMS
CEILING
12’ OR
LESS
FLOOR
DWG# 55-4