Fire-rated window assemblies close to side property line.

[Mike NY]

We are designing a new project located in Mamaroneck, NY. It is a 4 story mixed use building. It is a R-2 IIIB Construction. The interior is sprinkled. We need to put windows in a wall that is located 3'2" from the side property line. The total wall opening % for the windows is around 22%. The approach we are taking to get to less than 15% protected openings is to make most of the windows 45 minute fire-rated assemblies and for the remaining windows to be 1 hour rated assemblies so that these can qualify as a wall and not count as an opening. Is this the right approach in regards to the fire-ratings? We are trying to use steel frame windows made by Optimum.
Thanks.

[Jerry Peck - Codeman]

We are designing a new project located in Mamaroneck, NY. It is a 4 story mixed use building. It is a R-2 IIIB Construction. The interior is sprinkled. We need to put windows in a wall that is located 3'2" from the side property line. The total wall opening % for the windows is around 22%. The approach we are taking to get to less than 15% protected openings is to make most of the windows 45 minute fire-rated assemblies and for the remaining windows to be 1 hour rated assemblies so that these can qualify as a wall and not count as an opening. Is this the right approach in regards to the fire-ratings? We are trying to use steel frame windows made by Optimum.
Thanks.

The following is from the 2010 New York State Building Code on the ICC site: (bold and underlining are mine)
( http://publicecodes.cyberregs.com/st/ny ... 010-999999 )
- 702.1 Definitions
- - FIRE SEPARATION DISTANCE. The distance measured from the building face to one of the following:
- - - 1. The closest interior lot line;
- - - 2. To the centerline of a street, an alley or public way; or
- - - 3. To an imaginary line between two buildings on the property.
- - - The distance shall be measured at right angles from the face of the wall.
- 704.2 Projections.
- - I presume you meet the requirements and limitations of this section.
- 704.5 Fire-resistance ratings.
- - I presume the exterior wall is fire-resistance rated from both sides per this part of this section: "The fire-resistance rating of exterior walls with a fire separation distance of 5 feet (1524 mm) or less shall be rated for exposure to fire from both sides."
- 704.8 Allowable area of openings. The maximum area of unprotected or protected openings permitted in an exterior wall in any story shall not exceed the values set forth in Table 704.8. Where both unprotected and protected openings are located in the exterior wall in any story, the total area of the openings shall comply with the following formula:
- - (see code for formula, note that the percentage is based on the exterior wall area of any story and not of the entire exterior wall area)
- Table 704.8 Maximum Area Of Exterior Wall Openings a (note a says: a. Values given are percentage of the area of the exterior wall.)
- - Fire Separation Distance of Greater than 3 feet up to 5 feet - unprotected openings: "Not permitted" c (note c says "c. For occupancies in Group R-3, ... " which means note c is not applicable because you are working with a Group R-2 occupancy.) - end result is that no unprotected openings are permitted ... unless your sprinkler system meets 903.3.1.1 (see below).

What type of sprinkler system are you using?

I ask because: 704.8.1 Automatic sprinkler system. In buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, the maximum allowable area of unprotected openings in occupancies other than Groups H-1, H-2 and H-3 shall be the same as the tabulated limitations for protected openings.

903.3.1.1 is a full NFPA 13 sprinkler system. If the sprinkler system you are using is an NFPA 13R then there is no allowable calculating the unprotected openings as protected openings. And because the occupancy is R-2, no unprotected openings are permitted.

It is easy to lose track of where one is in these reviews, if I missed something or the above does not compute (such as 2+2=5) let me know and I will go back through it.

[Mike NY]

Thanks for your answer. The sprinkler system is NFPA 13, Not NFPA 13R, according to the sprinkler plans.
There is one thing that I am not clear about. If a window assembly is one-hour fire rated for both sides, does it technically count as a wall and not an opening?

[Jerry Peck - Codeman]

There is one thing that I am not clear about. If a window assembly is one-hour fire rated for both sides, does it technically count as a wall and not an opening?

My apologies, I missed that question in your previous post - a rated fire window assembly is still considered to be an opening. I know that some AHJ approve things which are not in compliance with the stated code requirements by applying the alternate materials, design and methods in the various codes.

In the 2010 New York code the alternate materials, design and methods section is here:
- 103.3 Alternate materials, design and methods of construction and equipment. This code is not intended to prevent the use of any material not specifically prescribed by this code or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative material, design or method of construction has been approved by the code enforcement official or the State Fire Prevention and Building Code Council. An alternative material, design or method of construction may be approved only when the code enforcement official or the State Fire Prevention and Building Code Council shall have determined, in writing, that such alternative material, design or method of construction (1) complies with the intent of the provisions of this code and (2) is at least equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety. Nothing in this section 103.3 shall be construed as permitting any code enforcement official, or any town, village, city, county, or state agency charged with the administration and enforcement of the Uniform Code, to waive, vary, modify or otherwise alter any provision or requirement of this code or any other provision or requirement of the Uniform Code. Provisions or requirements of the Uniform Code may be varied or modified only pursuant to procedures established by the Secretary of State pursuant to section 381(1)(f) of the Executive Law.

You could check with your Building Official to find out how they would address that specific question. Keep in mind that if the AHJ approves such use under the alternate materials, design and methods section, the Fire Marshall would also need to approve such use under the Fire Code of New York State:
- 101.4.6 Fire prevention. The provisions of the Fire Code of New York State shall apply to matters affecting or relating to structures, processes and premises from the hazard of fire and explosion arising from the storage, handling or use of structures, materials or devices; from conditions hazardous to life, property or public welfare in the occupancy of structures or premises; and from the construction, extension, repair, alteration or removal of fire suppression and alarm systems or fire hazards in the structure or on the premises from occupancy or operation.