Hambro® brings you one of the finest fire rated structural
floor systems in the world.
There are many accepted methods to achieve satisfactory fire
protection with the Hambro floor system. Extensive fire
testing has been performed by Underwriters
Laboratories (UL) resulting in many milestones and again
proving the superior performance of the Hambro® system. The
full scale fire tests are performed while the system is loaded
to its full design capacity and the results are as follows:
NOTE: See UL Designs for details.
Gypsum Board Membrane
Gypsum “drywall” ceiling membranes (Type C) installed
directly under Hambro® joists are generally used in residential
construction. They are economical; aesthetically pleasing
and can safely accommodate integrated sub-systems, recessed
light fixtures and ventilating units without impairing their
fire rating capabilities. UL
Design No. G-524 has been the most popular Hambro® rating for residential applications due to its enormous flexibility.
For each 100 square feet of ceiling area, it allows unprotected
ceiling penetrations up to 256 square inches for 1 hour (See
UL item 10Q), 196 square inches for 1.5 hours (see UL item
10F) and 100 square inches for 2 hours (see UL item 10K).
This design permits unshielded, non-metallic electrical wiring
for up to 2 hours; and for 1 hour, as an alternate to the
unprotected duct outlet, 2 & 4 inch PVC pipe is permitted
per 100 square feet of ceiling area to run throughout the
Hambro® plenum, penetrate the ½ “ ceiling
and run down through non-rated partition wall (see UL item
You can also substitute unprotected duct outlet with unprotected
recessed light fixtures, up to 4 standard 6 ½ “
diameter high hats per 100 square feet for a one hour rating
(see UL item 10H). Always consult the latest listing published
Gypsum Board Membrane UL Designs:
Suspended or Lay-in Ceiling
Accessible ceiling panels commonly referred to as "lay-in”
ceiling tiles are generally used in office, commercial and
institutional construction. These removable fire rated panels
allow access to the ceiling plenum for alterations to mechanical
or electrical equipment. Any penetrations to the assembly
need to be protected as per the UL design.
Suspended or Lay-in Ceiling UL Designs:
G-003, G-201, G-213,
Insulating the Hambro® joists by sprayed on fireproofing
is another accepted method of fire protection. This option
is typically selected when there would be so many protected
openings that spray becomes a cost effective alternative or
spray can also provide flexibility to future tenants who want
the option to use a non-rated ceiling of their choice.
Sprayed-on Fireproofing UL Designs: G-702,
Through-Penetration Firestop Systems for the G-500 Series Design
Through-penetration firestop systems are intended to restore the hourly rating of fire-resistive assemblies that have been breached due to penetration by electrical, plumbing or mechanical items.
Through-Penetration Firestop Systems : F-E-1001, F-E-1002, F-E-1003, F-E-2001, F-E-2002, F-E-2003, F-E-2004, F-E-3001, F-E-3002, F-E-3003, F-E-3004, F-E-5001, F-E-7001, F-E-7002, F-E-8001, F-E-8002, F-E-8003.
The above links are to the UL Designs that incorporate Hambro® joists. Always check your UL Directory for the latest updating
of these listings and applicable building codes before detailing