UL Design for Metal Deck

Log Out | Topics | Search Moderators | Register | Edit Profile

Author Message Richard Baxter, AIA, CSI Senior Member Username: rbaxter Post Number: 57 Registered: 12-2004 Posted on Wednesday, October 03, 2007 - 05:25 pm:    I’ve finally run out of resources and I’m hoping someone here can help. This must be a national holiday for SFRM product reps. The architect wants an exposed exterior structural metal deck (for a canopy on a top level of a parking garage) to be 1 hour fire-rated without using any fireproofing materials below the deck. He says intumescent products will be too costly for the thickness that would be required for an exposed structural steel deck with nothing on top, so he wants some kind of cheaper lightweight cementitious product to be poured on the deck to create the required 1-hour UL rating without SFRM products below the deck. Is that possible? Does anyone know a UL Design that covers it? All the UL Designs I can find either include a ceiling below the deck or require sprayed-on fireproofing. As a side question, to what extent are we at liberty to not include a component indicated for the UL Design? Does the component have to be indicated on the UL Design as ‘optional’ before we can exclude it? It seems to me, for example, that eliminating the roof membrane from a concrete deck might not decrease the fire rating. Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 534 Registered: 03-2003 Posted on Wednesday, October 03, 2007 - 05:44 pm:    I'll look into it, but I need some info: 1. Open or enclosed parking structure? 2. Number of tiers? 3. Area per tier? 4. Do canopies cover the entire upper level or just the parking spaces? Richard Baxter, AIA, CSI Senior Member Username: rbaxter Post Number: 58 Registered: 12-2004 Posted on Wednesday, October 03, 2007 - 07:29 pm:    Thank you Ron 1. It is an open precast concrete parking structure that is open on 3 sides, but shares a wall with a Casino. Since the Casino is also attached to a conference center and a hotel, someone decided that the whole complex of buildings should be designed as group A 1. The steel canopy is composed of steel columns and steel trusses supporting a metal deck. Structural engineers want it as light as possible. Architect wants it as inexpensive as possible. I am told it has to be 1-hour rated because of the group A-1 status. 2. There are 3 tiers. There are actually two parking structures, each attached to the Casino. 3. The areas per tier is 64,728 sq. ft. 4. The canopy covers the central 31,000 sq. ft of the top tier. It covers 2/3rds of the parking stalls and the ramps to and from the 2nd level. Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 535 Registered: 03-2003 Posted on Wednesday, October 03, 2007 - 07:48 pm:    Oh, another thing I should have asked...what building code is applicable? Richard Baxter, AIA, CSI Senior Member Username: rbaxter Post Number: 59 Registered: 12-2004 Posted on Wednesday, October 03, 2007 - 08:22 pm:    2003 IBC Mark Gilligan SE, CSI New member Username: mark_gilligan Post Number: 1 Registered: 10-2007 Posted on Thursday, October 04, 2007 - 01:47 am:    Most metal decks have a 2 hour rating if there is 3-1/4" of 110 pcf light weight concrete on top of the deck. Check with the metal deck manufacturer. Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 537 Registered: 03-2003 Posted on Thursday, October 04, 2007 - 02:19 am:    Richard: First, from the description you gave, I don't see how this is an A-1 occupancy unless you have a theater of some sort with fixed seating. It's probably more of an A-3 occupancy. But, for your situation, the A occupancy group will be the most restrictive, regardless of specific use since the A occupancies are very similar to each other. From what you've described, it sounds like you're going with the nonseparated use method, and to achieve that and only have a 1-hour roof rating, plus include all that floor area, you're looking at Type IB construction. However, to avoid the roof situation that you mentioned, you might want to look at using a fire wall to make the parking structure a separate structure. You're going to have to separate the parking structure from the rest of the building anyway with a 2-hour fire barrier (1-hour if the building is sprinklered throughout, including parking garages) in accordance with Section 406.2.7. By using a fire wall to create separate structures, you can now classify the parking garage as Type IIB construction, which has no fire-resistive requirements for any building element. This can be achievable only if the parking garage is "open" on 3/4 of the perimeter (see what constitutes an "opening" in Section 406.3.3.1) to give you a 25% area increase to the 50,000 sq. ft. allowed per tier for Type IIB construction (See Table 406.3.5 and Section 406.3.6) to cover the over 64,000 sq. ft. per tier of your parking garage. The number of tiers in your garage is well below the allowable 9 (8 plus one for the 3/4 open perimter). I hope this helps. John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 797 Registered: 03-2002 Posted on Thursday, October 04, 2007 - 07:57 am:    As to not including a component in a UL listing: it is no longer a rated assembly. This is one of the problems with the tested assembly approach. It's totally prescriptive. Maybe someday, with the advent of computer modeling techniques, we will be able to design assemblies based upon their predicted fire performance as modeled. Kind of like the approach NFRC uses for U-factor. Richard Baxter, AIA, CSI Senior Member Username: rbaxter Post Number: 60 Registered: 12-2004 Posted on Thursday, October 04, 2007 - 10:29 am:    Thanks for the help. Ron, There is an auditorium, with fixed seating, in the conference center that also shares a wall with the parking garage. I advised the project architect to make the parking garage a separate use, but apparently the Owner wants it all non-separated. Mark, Thanks for the info. I will check with the metal deck manufacturers. Do you happen to know what UL Design number they use for the rated metal deck with lightweight concrete topping? They might be offering the rated decks assuming that there will be a ceiling below the deck or that the deck will be sprayed with fireproofing. Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 539 Registered: 03-2003 Posted on Thursday, October 04, 2007 - 02:45 pm:    Richard: The IBC requires the entire floor area to be sprinklered where an A occupancy is located; this would include the parking garage, as well. With a 2-hour fire wall, the parking garage can be treated as a completely separate building from the casino, and not have to have a sprinkler system, which could save you money (unless a local amendment requires a sprinkler system in the parking garage). An 8-inch masonry wall will give you the two-hour protection, and any openings will need to have a 90-minute rating--a simple tradeoff for sprinklering the parking garage. Plus, you can use the Type IIB construction and not have to protect any building element of the parking garage, assuming you meet the opening requirement I mentioned in my earlier post. Correction: I previously mentioned that a 2- or 1-hour fire barrier was required between the parking garage and the rest of the building regardless if the building was using non-separated uses. The reference to Section 302.3.2 for separated uses was modified in the supplement and in the new 2006 edition to refer to Section 302.3, which includes all methods. Mark Gilligan SE, CSI Junior Member Username: mark_gilligan Post Number: 2 Registered: 10-2007 Posted on Thursday, October 04, 2007 - 05:12 pm:    The ratings for metal deck with light weight concrete do not require ceilings or sprayed on fireproofing. Remember these tests were paid for by deck manufacturers and they want to make their product as competitive as possible. Adding the other components would only limit the use of their product. Randall A Chapple, AIA, SE, CCS, LEED AP Senior Member Username: rachapple Post Number: 11 Registered: 12-2005 Posted on Tuesday, October 09, 2007 - 12:09 pm:    As far as modifications to tested systems, the manufacture who did the test can provide judgment letters that would address modifications to their systems.