Firestopping, Part I
What is that red, silly putty all over those pipes and penetrating the wall? If it is red, is it really good. What if it is not red? Do pipes penetrating gypsum board stud walls require an approved firestopping system? Is firestopping one word?
In this set of columns, I will attempt to address these and other questions related to firestopping. The focus of these columns will be those issues affecting the plumbing engineer.
Let us start with some firestopping basics. References will be to the 2015 IBC unless otherwise noted.
The firestopping requirements are found in Section 714 Penetrations. Generally, a penetration of a fire-resistant rated wall requires some form of protection. Likewise, the penetration of a fire-resistant rated horizontal assembly not protected with a shaft also requires protection.
Section 714.3 addresses penetrations of walls, including fire walls, fire barriers, fire partitions and smoke barrier walls. Penetrations are classified in one of two categories. A through penetration is defined as, “a breach in both sides of a floor, floor-ceiling or wall assembly to accommodate an item passing through the breaches.” Here is a case where violating the prohibition against using the word in the definition of the word would have made sense.
The other type of penetration is the membrane penetration defined as a, “breach (ugh!) in one side of a floor-ceiling, roof-ceiling or wall assembly to accommodate an item installed into or passing through the breach.” For example, an electrical receptacle located in a stud wall which only penetrates one side of the wall.
Through penetrations in general must be protected with an approved through penetration firestop system which has been tested in accordance with ASTM E814 or UL 179. There are some important exceptions to this. If maximum 6-inch diameter steel or copper pipes, tubes or conduits penetrate a concrete or masonry wall, the annular space around the penetrating items can be filled with concrete, grout or mortar to the full thickness of the wall provided the penetration is less than 144-square inches. Keep in mind that if this is done with sprinkler piping requiring earthquake protection then flexible couplings will be needed on either side of the wall.
A firestop system is also not required if the fill material prevents the passage of flame and hot gas as specified in 714.3.1 Exception 2. I think this provision could be used to permit a judgment that one may patch small penetrations of gypsum wallboard with joint compound. Through penetration firestop systems must have an F rating equal to or greater than the fire resistance of the assembly. F rating is defined as, “the time period that the through-penetration firestop system limits the spread of fire through the penetration when tested in accordance with ASTM E 814 or UL 1479.”
Section 714.3.2 addresses protection of membrane penetrations of walls requiring an approved fire stop system complying with Section 714.3.1. There are several exceptions, most of which are related to membrane penetration by electrical items. Exception 4 applies to non-electrical boxes. This can be applied in cases where plumbing is provided in rated chase walls. This exception also requires an approved membrane penetration firestop system with both an F rating and a T rating. T rating is defined as, “the time period that the penetration firestop system, including the penetrating item, limits the maximum temperature rise to 325 F (163 C) above its initial temperature through the penetration on the nonfire side when tested in accordance with ASTM E 814 or UL 1479.”
Exception 5 allows a non-firestopped annular space created by the penetration of a sprinkler as long as the space is covered by a metal escutcheon plate. Note that this is for membrane penetration only. A through-penetration of the wall by a sprinkler pipe on one side to sprinkler head on the other side would not be able to use this exception.
Section 714.4 addresses horizontal assemblies. There are exceptions similar to those contained in Section 713 for walls. There is also an exception for listed electrical boxes that have been tested in the assembly. Section 714.4.1 requires through-penetrations be protected with an approved through-penetration firestop system with both an F rating and T rating. There are three exceptions to the T rating requirement, two being applicable to the plumbing trades. The T rating is not required for floor penetrations that occur with the cavity of a wall, and floor penetrations by, “floor drains, tub drains or shower drains contained and located within the concealed space of a horizontal assembly.”
Section 714.4.2 addresses membrane penetrations of floors. Of the several exceptions, Exception 1 deals with penetrations of, “steel, ferrous or copper conduits, pipes, tubes or vents.” Exception 5 is the permission for sprinklers with metal escutcheons.
The penetration of smoke barriers is addressed in Section 714.4.4. The penetration must be protected by an approved through-penetration firestopping system that also is leakage rated, i.e., has an L rating. L rating is defined as, “the air leakage rating of a through penetration firestop system or a fire-resistant joint system when tested in accordance with UL 1479 or UL 2079, respectively.”
The last section, 714.5 contains provisions addressing penetrations of floor/ceiling and roof/ceiling assemblies that do not carry a fire resistance rating. The requirements for firestopping in NFPA 5000 are very similar, see Section 8.8 of the 2015 edition.
Next month, my column will continue to look at firestopping.
Samuel S. Dannaway, P.E., is a registered fire protection engineer and mechanical engineer with bachelor’s and master’s degrees from the University of Maryland Department of Fire Protection Engineering. He is past president and a Fellow of the Society of Fire Protection Engineers. He is president of S. S. Dannaway Associates Inc., a 15-person fire protection engineering firm with offices in Honolulu and Guam. He can be reached via email at SDannaway@ssdafire.com.