R-2 Area Increase

[Mech]

2009 IBC

New Type 5 Construction and I am assuming it is type B (Architect is no longer part of the team)

R-2 Apartment Building

Sprinklered in accordance with NFPA 13R

Allowable floor area is 7,000 sf. Chapter 9 requires sprinklers in Type R occupancies. Can the allowable building area be increased due to the sprinkler system per 506.3?

506.3 Automatic sprinkler system increase. Where a building is equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1, the building area limitation in Table 503 is permitted to be increased by an additional 200 percent (Is= 2) for buildings with more than one story above grade plane and an additional 300 percent (Is= 3) for buildings with no more than one story above grade plane. These increases are permitted in addition to the height and story increases in accordance with Section 504.2.

Exception: The building area limitation increases shall not be permitted for the following conditions:

1. The automatic sprinkler system increase shall not apply to buildings with an occupancy in Group H-1.

2. The automatic sprinkler system increase shall not apply to the building area of an occupancy in Group H-2 or H-3. For buildings containing such occupancies, the allowable building area shall be determined in accordance with Section 508.4.2, with the sprinkler system increase applicable only to the portions of the building not classified as Group H-2 or H-3.

3. Fire-resistance rating substitution in accordance with Table 601, Note d.

Thanks in advance.

 

[Francis Vineyard]

No, Section 506.3 is for NFPA 13 only, to get the area increase with 13R must use exception 2 in single occupancy buildings in accordance with 506.4.1

Exception 2 is an increase allowed for residential sprinkler systems installed in accordance with NFPA 13R. The area increases allowed by :Next('./icod_ibc_2009f2cc_5_par023.htm')'>Section 506.3 are only applicable when the building is to be equipped with a sprinkler system in accordance with NFPA 13—not NFPA 13R. The three-story multiplier limit or "three-story cap" was initially evaluated based upon use of area increases resulting from the installation of an NFPA 13 system. Since buildings equipped with an NFPA 13R system are not allowed an area increase, it was determined that the "three-story cap" had an unintentional detrimental impact on residential buildings. Specifically, for a four-story residential building with an NFPA 13R sprinkler system, the provisions of :Next('./icod_ibc_2009f2cc_5_par025.htm')'>Section 506.4.1 would reduce the area per story and the total building area. Given that the maximum height of buildings with NFPA 13R systems is four stories, this application of an increase in allowable area was determined to be warranted.

http://publicecodes.cyberregs.com/icod/ibc/2009f2cc/icod_ibc_2009f2cc_5_sec006.htm

 

[Frank]

If don't have height and area resolved and the architect is no longer part of the team it looks like time to recruit another architect to finish the job.

 

[Mech]

Frank - Plans are finished and approved. GC asked us if he could remove the 2 hour fire rated construction between the sprinkler room and a utility room. GC is afraid to ask the inspector for some reason.

With Francis' helpful post, I learned something new about Residential buildings (we rarely work on Residential buildings.) It turns out the 2 hour rating is actually a fire wall and is required so the building complies with the allowable building area. Sprinklers do not allow a building area increase, so the 2 hour wall must remain.

If the GC would have asked the architect, he could have had an answer in less than half an hour. But hey, we are keeping the GC happy (repeat business) and I am getting paid to learn more of the code.