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Fire Barrier Rating - Control Areas

sdpaddler50

Bronze Member
Joined
Sep 18, 2012
Messages
44
Scenario: Type V-N (wood roof and conc walls), 1 story, housing S-1 (rack storage of widgets). A control area is provided to allow storage of combustible liquids, so that the MAQ of these liquids is not exceeded.

Table 2703.8.3.2 (2009 IFC) allows up to 4 control areas (we have 2) and the fire barrier rating resistance required is 1 hour - so we are good to go. Footnote "b" says "Fire barriers shall include walls and floors as neccessary to provide separation from other portions of the building.

So, my question/concern; Why would the code not also require the ceiling/roof to be 1 hour rated for this control area? Why just the wall? Fire travels vertically, and if flammable liquids are involved, it's going to spread to the wood roof unless the sprinklers control it. I know the intent with control areas is to compartmentalize the building, so only the one area where the fire starts is involved, and hopefully the rest of the building is saved. But, if a fire gets in to a combustible wood roof, there is a good chance it will keep spreading across the entire building, regardless of how many fire barriers walls are present. Keep in mind, we are talking about a fire barrier per 707, not a fire wall as covered in 706, that has a 3 ft parapat, end wall proejections, etc.

Thanks in advance.
 
Maybe because it is not required normally in similar situations??

Like if you had a H against a B?? You would rate the wall between them, but normally not the ceiling of the H??
 
I'd say because the control area is intended to separate material quantities from horizontal and vertical fire spread. Shouldn't have any H material in the attic. Don't think the definition of fire area includes the roof. Plus the H fire area would be sprinklered.
 
-In a flammable liquids room, a rated ceiling is required by both NFPA 30, and FM. Any properly designed flam liq room i have worked on had a min 1, or sometimes 2 hour lids depending on various factors.

-If we are trying to “separate material quantities from horizontal and vertical fire spread” as you note, then why in the h$% would we not have a rated ceiling. I didn’t say anything about liquids in the attic space. I am referring to the ceiling (lid) directly over the room, which is usually about 10 ft high in a typical, small, liquid room. The projects I have worked on, they simply add a few layers of dry wall to the ceiling, and you are good.

I believe the IBC/IFC should be requiring fire rated ceilings, in addition to the walls for the reasons I have noted above. I dont believe the provision of a rated wall is always going to stop a fire at the wall, and confine the fire to a control area when a wood (combustible) roof is directly overhead, and a heavy fuel load such as low f.p. flammable liquids are involved. Large fires have occurred in the past that had rated walls, but the fire still involved the combustible roof deck, and a total building loss occurred.
 
Have to look at Nfpa have done a room in so long

Do you have a section reference???

Maybe Mr. Wonderful/ Haz will add some words of wisdom
 
sdpaddler50 - look at continuity of fire barriers. The deisgn would either terminate at the roof deck without ( an attic) or terminate at a rated ceiling enclosure (Lid as you are proposing)

In multistory buildings, (414.2.4 Fire-resistance-rating requirements) The required fire-resistance rating for fire barriers shall be in accordance with Table 414.2.2. The floor construction of the control area and the construction supporting the floor of the control area shall have a minimum 2-hour fire-resistance rating.

Exception: The floor construction of the control area and the construction supporting the floor of the control area is allowed to be 1-hour fire-resistance rated in buildings

of Type IIA, IIIA and VA construction, provided that both of the following conditions exist:

1. The building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, and

2. The building is three stories or less in height

The only control area that would be allowed to terminate at a unrated ceiling would be the control areas on the top floors....then the fire barriers would terminate at the bottom of the unrated ceiling assemlbly
 
Builder Bob, in a 1 story, S-1, Type V warehouse example, you would not need a rated ceiling. The 1 hr wall in between the control areas is all that is needed. There is no requirement to provide sheet rock, or any other type of fire resistant materials on the underside of the ceiling in my interpretation of the code. If we then load that control area with 120 gals of a low flashpoint flammable liquid, the fire can quite easily involve the roof deck. Sprinklers to control it? – well, unless they are designed to handle the flammable liquids with an extremely high density and/or foam, the fire will spread to the combustible wood roof. My assertion is therefore that if we are asking for 1 hour walls to have up to 4 control areas loaded with flammable liquids in a building, then we (code) should require a rated ceiling as well. I am not referring to a suspended ceiling like an office has, but a true, min 1 hour rated ceiling of a couple layers of sheet rock. I am not a BO, so I am just throwing this out there for others to consider.
 
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