Why are dampers and exhaust fans specified in some designs and not others?

The manufacturers who sponsor a test determine which products will be part of the tested assembly and not every construction scenario is tested.  So some assemblies are tested with dampers or exhaust fans while others are not. 

What is a ceiling radiation damper? 

• Ceiling radiation dampers are used to protect penetrations through the ceiling membrane of fire rated floor-ceiling designs.  

Can I add a damper to a design that was not tested with one?

• If a design has not been tested with a damper, you cannot add one without code authority approval.

What type of equipment can be used in conjunction with a damper?

• UL certified equipment like exhaust fans and ductwork can be used in conjunction with a certified damper. These specifications are contained within the tested design. Manufacturers are always interested to know if a product, based upon demand, needs to be included in a test. Design professionals should contact manufacturers when they cannot find a tested construction scenario.

If a UL floor-ceiling Design shows a generic hinged door damper in the construction specifications, what type of listed and labeled damper is permitted to be installed in this assembly?

• The BXUV Guide information, specifically section III, subsection 16, states that Certified Ceiling Dampers (CABS) may be used in lieu of the hinged-door-type dampers in those designs that employ air ducts with the duct outlet protected with a hinged-door-type damper.

Refer to the Damper Marking and Application Guide for even more information on this subject.