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Fire rated floor register penetration

M

Michael Brown

Sawhorse
Joined
Mar 27, 2017
Messages
34
Location
Covington, GA
The engineer has submitted a drawing that is four townhouse style units. As designed, the walls are supposed to be sufficient to treat each unit as an individual and not require any fire dampers. The GC has stated that walls are not rated as such and fire dampers will be required and the rated assembly is an L528. The L528 assembly has no listed fire dampers that could be used to protect the floor register penetrations and I cant seem to get the engineer to understand this. Their last response was "Any type B damper will work". Does naybody know of or have an example of a fire damepr being used to protect a floor register penetration. Or anything else to add?
 
Sooo... if these are townhouse style units, aren't the wall between units required to be rated for dwelling unit separation???

If the duct is running in the trusses and the opening you are talking about is coming from that duct and up through the floor, there are no dampers I know of listed for that application. Any dampers out there are either fire dampers for a full through penetration of the entire assembly or radiation dampers to protect a ceiling membrane penetration DOWN through the ceiling, not up through the floor.

Ask the engineer to spec out proper dampers for the application. Its his design. Any listed damper will be VERY specific in what application it can be used.

I'm not even sure what a type B damper is. Been inspecting HVAC for 18 years after 13 years in the field.
 
klarenbeek said:
Sooo... if these are townhouse style units, aren't the wall between units required to be rated for dwelling unit separation???

If the duct is running in the trusses and the opening you are talking about is coming from that duct and up through the floor, there are no dampers I know of listed for that application. Any dampers out there are either fire dampers for a full through penetration of the entire assembly or radiation dampers to protect a ceiling membrane penetration DOWN through the ceiling, not up through the floor.

Ask the engineer to spec out proper dampers for the application. Its his design. Any listed damper will be VERY specific in what application it can be used.

I'm not even sure what a type B damper is. Been inspecting HVAC for 18 years after 13 years in the field.
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I'm with you that I've never seen a damper in this application.
 
Michael Brown said:
I dont know. We have done other builds of this type that dont require the protection
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If it's not separating units, it shouldn't have a required FRR. I have seen multifamily architects absent mindedly tag floor assys in townhomes as rated just out of habit. If the units aren't stacked above each other it is extremely unlikely that the floor/ceiling assy needs to be rated.
 
redeyedfly said:
If it's not separating units, it shouldn't have a required FRR. I have seen multifamily architects absent mindedly tag floor assys in townhomes as rated just out of habit. If the units aren't stacked above each other it is extremely unlikely that the floor/ceiling assy needs to be rated.
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I agree but the GC is the one insisting that it is a rated assembly. I keep pushing back for the damper specs but I think the engineer is being lazy and not really looking at it. Meanwhile, half of their project is at a standstill.
 
It might need to be rated if the floor is supporting fire rated assemblies, but designers usually try to get rid of that issue in the design phase, so we don't have to worry about it.

I'm with klarenbeek on this one. It would appear that no damper is required, so you can install whatever you want and bill them for it.

To be fair to the GC, "any type B damper will work" is actually true, because there is nothing required.

...now if only there was such a thing as a type B damper we would be all set...
 
I see what they're calling a type B damper now... Blades offset out of the air stream. Without the actual installation instructions I don't know for sure but this looks like a standard fire damper which would be for a full through penetration of the floor assembly. IMC 607.2 requires fire dampers to be installed per manufacturer's instructions. My guess is that can't be done in this application.

I inspected a 4 story apartment building a few years ago where there were three 2-story units and the builder brought the main building floor ceiling assembly through those apartments rather than walling them off from the rest of the building. Any membrane penetrations on the bottom of that floor ceiling assembly were protected with radiation dampers to protect the structure of the floor ceiling assembly but any runs going from the duct trunks in the trusses going up through the floor had no dampers. There's no dwelling unit separation there, the only thing needing protection is the structure itself, which the radiation dampers do. Code requires dampers at membrane penetrations which was done and at through penetrations. There were no straight through penetrations where a fire damper would be required. There are no requirements for dampers where the floor only is penetrated.
 
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