Ken, It boils down to performance. The desired performance is simple, keep a fire from spreading into adjacent units for two hours. It's really that simple.
There are two other ways of looking at this. First, If these were two separate structures the code would require them to be separated by at least 10 ft (5 ft to each property line). If that separation distance was not possible an alternative would have to be provided. That alternative would be a fire rating of the exterior walls including limiting openings. The performance objective is achieved by a) distance or b) fire resistance. If you're interested NIST did a study and a report generated; "Its too close" I was at NIST in 2002-2003 when the props where under construction. Interesting reading. Second, Height and area. If this were one building and 3 or more dwelling units it wouldn't qualify under the IRC since the IRC is limited to one and two family dwellings, it would revert to the IBC as a multiple dwelling, an R2 use in this case. With that table 503 invokes height, area, construction type and most importantly NFPA-13 or 13R sprinkler system requirements, not 13D or P2904. The performance objective is achieved by a) height, area and construction type and b) fire suppression. With that said its important that we stay focused on the intent, that being the intended performance under fire conditions. If the wall collapses prematurely, i.e. prior to 2 hrs, the collapse of the adjacent structure...then the performance is not achieved and the fire spreads. Its really that simple. Frankly I don't agree with the proposed reduction for sprinklers, unless of course we're going full 13 since neither 13R or 13D provide comprehensive building fire protection needed to limit fire spread. Tomatoe, Tomato, Potatoe, Potato......we know what they taste like no matter what their called. Hope that helps, John Drucker Jr, CET Fire Protection Subcode Official Fire/Building/Electrical Inspector New Jersey PS, Today's the last day to submit comments in support of sprinklers in one and two family dwellings in the State of New Jersey. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ken Holsopple (forum) Sent: Thursday, November 05, 2009 4:36 PM To: [email protected] Subject: RE: Townhouse or Apartment Building John, Unless I misunderstood your post, does this boil down to ICC definitions? FIRE-RESISTANCE RATING. The period of time a building element, component or assembly maintains the ability to confine a fire, continues to perform a given structural function, or both, as determined by the tests, or the methods based on tests, prescribed in Section 703. FIRE WALL. A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall. Ken Holsopple >John D wrote: So just how do we build a common 2 hour fire resistance rated wall, remember it has to be common and not part of one building or the other. _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
