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:

Gypsum Board Membrane

Gypsum “drywall” ceiling membranes 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 10E).

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 before detailing.

Gypsum Board Membrane:
G-524, G-525

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:
G-003, G-213, G-222, G-227, G-228, G-229, G-236, G-243

Sprayed-on Fireproofing

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: G-702, G-802

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 ceiling construction.