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NFPA 13R Section 6.6.7.2 Outside the Dwelling Unit. 1

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sprinklerdesigner

Mechanical
Sep 8, 2006
10
I already know the answer to this but I am locking horns with one of the AHJ's and was wondering if anyone knows of a more definitive article somewhere.

I have a motel with corridors 5' wide x 150' long giving a compartment size of 750 sq. ft..

The corridor ceilings are smooth, flat and the ceiling height is 9'-0".

For these corridors I elected to utilize residential sprinklers spaced 20' on centers for the corridors. In accordance with their listing which requires four sprinklers be calculated which, when spaced 20', require a discharge of 20 gpm. As each head covers 100 sq. ft. at 20 gpm I exceed the required density of .10.

As stated the local AHJ has a problem with me calculating only four sprinklers wanting me to calculate 5 heads per NFPA 13 since I am outside the dwelling unit and the "compartment" exceeds 500 sq. ft..

6.6.7.2.2 Residential sprinklers shall be permitted to be used in corridors leading to dwelling units and in areas covered by 6.7.2.2, 6.7.2.3 and 6.7.3.3.

6.7.2.2 The system demand of areas outside the dwelling unit shall be permitted to be limited to the number of sprinklers in the compartmented area but shall not be greater than the demand for a total of four sprinklers where all of the following conditions are met:
(1) The area is compartmented into areas of 500 ft2 (46 m2) or less by 30-minute fire-rated construction.
(2) The area is protected by quick-response or residential sprinklers not exceeding 130 ft2 (12 m2) per sprinkler for ordinary hazard, 225 ft2 (20.9 m2) for light hazard, or the allowable coverage of the sprinkler listing.
(3) Openings have a lintel at least 8 in. (203 mm) in depth.
(4) The total area of openings does not exceed 50 ft2 (4.6 m2) for each compartment.
(5) Discharge densities are in accordance with NFPA 13, Standard for the Installation of Sprinkler Systems.

This is followed by:

6.7.2.3 The following types of spaces are permitted to be protected by residential sprinklers where they have flat, smooth ceilings not exceeding 10 ft (3.0 m) in height and are protected in accordance with the requirements for residential sprinklers:
(1) Lobbies not in hotels and motels
(2) Foyers
(3) Corridors
(4) Halls
(5) Lounges
(6) Other areas with fire loads similar to residential

To further substantiate the four sprinkler design is adequate I submitted this ROP from the NFPA website.


Here is a copy if you don't want to sift through the pdf file:


It is obvious, with 23 members out of 23 members voting in the affirmative to accept this proposal, the committee's intention was to require only four heads be calculated in corridors when residential heads are used and the requirements of 6.7.2.3 as to residential like occupancies, ceiling heights and ceiling construction.

The problem I am having is the local AHJ is interpreting the 500 sq. ft. compartment limitation contaned in 6.7.2.2 also applies to 6.7.2.3 which it doesn't.

Does anyone know of any sources that might clear it up for the local AHJ?
 
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Based on the NFPA 13R document you referenced, I find a couple code interpretations in your favor:

1.)
Section 6.6.7.2.1 states that outside dwelling units, the design shall satisfy NFPA 13, EXCEPT where permitted by Section 6.6.7.2.1. You point out that your project can be considered to satisfy a condition of this section, and therefore should be excepted from NFPA 13 provisions.

2.)
Section 6.7.2.1 states that the system outside a dwelling unit should satisfy NFPA 13, unless permitted by Section 6.7.2.2 through 6.7.2.4. You point out that your project can be considered to satisfy Section 6.7.2.3.

However, it is unclear if "through" refers to the project satisfying all 3 of the referenced sections, or just one. Based on the conditions of 6.7.2.3 and 6.7.2.4, it does not appear feasible for a project to satisfy both of those sections. Therefore, it can be concluded that the word "though" can be meant to be any/or, not all.

Since your situation satisfies 6.7.2.3, your system should not be required to satisfy NFPA 13.
 
>Since your situation satisfies 6.7.2.3, your system should not be required to satisfy NFPA 13.

Thing is almost any residential system, I design anyway, can handle the extra sprinkler as I usually "oversize" the "main" going down the corridor. On this particular job I could open seven heads in the corridor and still have a 30 psi "safety factor but that isn't the point.

All I want an AHJ to do is interpret the code correctly.

That should be clear to anybody but sometimes obtuse is to kind in describing some AHJ's.



 
First, let us refrain from bashing AHJs. This may be his/her first experience with NFPA 13R or any other project for that matter. While you and Aegis are competent design professionals I can assure you that I personally met several dozen well paid idiots with Autocad and hydraulic calculation software whom I educated on the use and interpretation of NFPA 13, 13R and a host of other design standards. I can post NFPA 13 Chapter 12 horror stories if you like.

A suggested strategy is to also explain that your proposed design is treated as a special design using NFPA 13, 2002 edition, section 11.2.3.4. The requirements are based on fire test results, the response time index of the sprinklers, and the moderate to low fuel mass found in corridors. This demonstrates consistency between both standards and that both committees made their decision based on the same facts.

Finally, do your shop drawings reflect the fire resistant assembly requirements specified in NFPA 13R? Note that the 2003 IBC requires the exit corridor in a sprinklered R-2 occupancy to have a 30 minute fire resistance rating, which is consistent with the NFPA 13R. IBC section 715 requires these doors have a minimum 20 minute resistance rating and be listed for smoke and draft control.

Your explanation should be include that corridor and openings provide passive protection (physical barriers against fire spread from the dwelling compartment to the corridor and visa versa), response time index (for QR sprinklers RTI must be < 50 versus conventional sprinklers having an RTI of 250-300) and the efficacy of the automatic sprinklers in corridors (very limited fuel load; fuel load is already limited by either the IBC or the LSC as to combustibles in exit paths) and Group R occupancies.
 
I may be oversimplifying this, but here goes:
If you can use residential sprinklers in the corridor, then why not just state that you are using

11.2.3.5 Residential Sprinklers.
11.2.3.5.1* The design area shall be the area that includes the four hydraulically most demanding sprinklers.

It is hard to dispute when it is right there in NFPA 13 for him to reference.

This seems like a slam dunk situation. I can't tell you how many AHJs we have had to educate on the use of residential heads in a 13 system since the new requirements were brought out in the 2002 edition of NFPA 13.
 
Hey Travis:

Still thinking about a move to God's country? Slower, easier pace and some really good food and great people.
 
Stookey:

My wife has been down to DFW area looking at homes. She is ready to move ASAP! Probably seriously start looking at the start of the year! She said it was beautiful down there.
 
Like I said before, look in the Fort Worth area, especially near Burleson. Lots of new homes that are affordable and your 20 minutes from downtown Fort Worth.
 
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