Fire-ratings
What is a Firecode™
Formulation?
USG offers ceiling products that are designed to meet life safety
codes. The industry evaluates life-safety compliance with two
ratings: flame spread/smoke developed and fire resistance. The
first is the Fire Class/Surface Burning Characteristics as defined
by ASTM E1264. All USG ceiling products are rated Class A (the best
rating possible) by these standards. This means that our products
do not exceed a flame spread rating of 25 and do not continue to
combust after the test flame has been extinguished. Also, as part
of our Class A designation, our products do not exceed a smoke
developed rating of 50.
In addition, ceilings are tested by Underwriters Laboratories, Inc.
for their resistance to the spread of fires within buildings. These
are hourly designations and measure the ceiling's ability to
protect occupants, fire fighters, and the building structure. The
most common rating is the one-hour rating, but USG offers ratings
up to three hours. These tests incorporate complete assemblies
involving ceiling/floor designs and ceiling/roof designs. USG
offers over 300 UL designs.
Are flame spread ratings and
fire-resistance ratings the same?
No, the ratings are two separate issues. A flame spread rating
relates to the relative rate at which flame will spread over the
surface of the material. The required standard for most commercial
applications is a flame spread rating of 25 or less (for Class A
ceilings). The fire-resistance rating relates to the ability of an
assembly to prevent the spread of fire between spaces wile
retaining structural integrity.
Do ceilings singularly provide
a fire rating?
Ceilings alone do not provide a fire rating. Fire-resistance
ratings apply only to a floor/ceiling or roof/ceiling assembly in
its entirety. Individual components such as ceiling panels or
suspended grid are not assigned separate fire resistance
ratings.
Do all UL fire-rated
assemblies require the use of hold down clips on ceiling
panels?
Hold down clips are only required for UL assemblies where ceiling
panels weigh less than 1 lb. Per square foot. All USG Firecode™
ceiling panels weigh 1 lb. per square foot and more and do not
require hold down clips.
What is a UL fire-rated
assembly?
UL fire-resistance ratings are applied to certain types of
floor/ceiling and roof/ceiling construction assemblies. Each is
tested to endure fire exposure for a given time period in
compliance with UL test conditions (Standard-ANSI/UL 263). The
resulting ratings are measured in hours and published in the UL
Fire Resistance Directory.
How can I get a copy of the UL
Fire Resistance Directory?
To obtain a copy, call (708) 272-8800 ext. 42612 or 42622, or write
to Underwriters Laboratories, Inc. Publications Stock, 333
Pfingsten Road, Northbrook, Illinois 60062.