N.Y.C. Admin. Code § BC 705: Section BC 705: Exterior Walls

705.1 General.

Exterior walls shall comply with this section. Exterior wall construction shall comply with the provisions of Chapter 14 and Appendix D where applicable.

705.2 Projections.

Cornices, eave overhangs, exterior balconies and similar projections, including but not limited to, fascias, belt courses, pilasters, surrounds, gutters, leaders, half-timber work, shutters, and trellises, extending beyond the exterior wall shall conform to the requirements of this section and Section 1406, provided that any such projection, if removed, altered or destroyed, will not reduce the structural stability of the building enclosure, and that such projection is installed so as not to reduce the required fire-resistance rating of the building enclosure. Exterior egress balconies and exterior exit stairways and ramps shall comply with the requirements of this section and Sections 1021 and 1027, respectively. Projections shall not extend any closer to the line used to determine the fire separation distance than shown in Table 705.2. Exterior wall coverings and cladding at exterior balconies and similar projections shall comply with Section 1406.3.

Exception: Buildings on the same tax lot and considered as portions of one building in accordance with Section 705.3 are not required to comply with this section.

Table 705.2 Minimum Setback Distance of Projection

Fire Separation Distance (FSD)

a

Minimum Distance from Line Used to Determine FSD

0 feet to 2 feet

Projections not permitted

Greater than 2 feet to less than or equal to 3 feet

24 inches

Greater than 3 feet to less than 30 feet

24 inches plus 8 inches for every foot of FSD beyond 3 feet or fraction thereof

30 feet or greater

20 feet

For SI: 1 foot = 304.8 mm; 1 inch = 25.4 mm.

a. Distance to be measured from the lot line, or lot line equivalent to the exterior wall.

705.2.1 Type I and II construction.

Projections from walls, including balconies on the exterior of buildings of Type I or II construction shall be of noncombustible materials.

705.2.2 Type III, IV or V construction.

Projections from walls of Type III, IV or V construction shall be of any approved material. Projections located where openings are not permitted or where protection of openings is required shall be constructed of the following:

1. Noncombustible materials.

2. Combustible materials of not less than 1 hour fire-resistant-rated construction.

3. Heavy timber construction complying with Section 2304.11.

4. Fire-retardant treated wood.

5. As permitted by Section 705.2.2.1.

705.2.2.1 Exterior balconies and similar projections.

Exterior balconies and similar projections shall be permitted to be constructed of combustible materials provided that the exterior balcony or similar projection affords the fire-resistance rating required by Table 601 for floor construction.

Exceptions: Balconies or similar projections serving as a required exit shall not be constructed of combustible materials.

705.3 Buildings on the same tax lot.

For the purposes of determining the required wall and opening protection, projections and roof-covering requirements, buildings on the same tax lot shall be assumed to have an imaginary line between them.

Exceptions:

1. Two or more buildings on the same tax lot shall be either regulated as separate buildings or shall be considered as portions of one building if the aggregate area of such buildings is within the limits specified in Chapter 5 for a single building. Where the buildings contain different occupancy groups or are of different types of construction, the area shall be that allowed for the most restrictive occupancy or construction.

2. Where an S-2 parking garage of Construction Type I or IIA is erected on the same lot as a Group R-2 building, and there is no fire separation distance between these buildings, then the adjoining exterior walls between the buildings are permitted to have occupant use openings in accordance with Section 706.8. However, opening protectives in such openings shall only be required in the exterior wall of the S-2 parking garage, not in the exterior wall openings in the R-2 building, and these opening protectives in the exterior wall of the S-2 parking garage shall be not less than 1 1/2-hour fire protection rating.

705.4 Materials.

Exterior walls shall be of materials permitted by the building type of construction.

705.5 Fire-resistance ratings.

Exterior walls shall be fire-resistance-rated in accordance with Tables 601 and 602 and Appendix D where applicable. The required fire-resistance rating of exterior walls with a fire separation distance of greater than 10 feet (3048 mm) shall be rated for exposure to fire from the inside. The required fire-resistance rating of exterior walls with a fire separation distance of less than or equal to 10 feet (3048 mm) shall be rated for exposure to fire from both sides.

705.6 Structural stability.

Exterior walls shall extend to the height required by Section 705.11. Interior structural elements that brace the exterior wall but that are not located within the plane of the exterior wall shall have the minimum fire-resistance rating required in Table 601 for that structural element. Structural elements that brace the exterior wall but are located outside of the exterior wall or wholly or partly within the plane of the exterior wall shall have the minimum fire-resistance rating required in Tables 601 and 602 for the exterior wall.

705.7 Unexposed surface temperature.

Where protected openings are not limited by Section 705.8, the limitation on the rise of temperature on the unexposed surface of exterior walls as required by ASTM E 119 or UL 263 shall not apply. Where protected openings are limited by Section 705.8 of this code, the limitation on the rise of temperature on the unexposed surface of exterior walls as required by ASTM E 119 or UL 263 shall not apply provided that a correction is made for radiation from the unexposed exterior wall surface in accordance with the following formula:

A

e

= A + (A

f

× F

eo

)

(Equation 7-1)

where:

A

e

= Equivalent area of protected openings.

A

= Actual area of protected openings.

A

f

= Area of exterior wall surface in the story under consideration exclusive of openings, on which the temperature limitations of ASTM E119 or UL 263 for walls are exceeded.

F

eo

= An "equivalent opening factor" derived from Figure 705.7 based on the average temperature of the unexposed wall surface and the fire-resistance rating of the wall.

For SI: °C = ((°F) - 32) / 1.8.

Figure 705.7 Equivalent Opening Factor

705.8 Openings.

Openings in exterior walls shall comply with Sections 705.8.1 through 705.8.6.

Table 705.8 Maximum Area of Exterior Wall Openings Based on Fire Separation Distance and Degree of Opening Protection

m

Fire Separation Distance (feet)

Degree of Opening Protection

Allowable Area

a

0 to less than 3

b, c

Unprotected, Nonsprinklered (UP, NS)

Not Permitted

Unprotected, Sprinklered (UP, S)

i

Not Permitted

Protected (P)

Not Permitted

j, k

3 to less than 5

d, e

Unprotected, Nonsprinklered (UP, NS)

Not Permitted

Unprotected, Sprinklered (UP, S)

i

15%

Protected (P)

15%

l

5 to less than 10

e, f, n

Unprotected, Nonsprinklered (UP, NS)

10%

h

Unprotected, Sprinklered (UP, S)

i

25%

Protected (P)

25%

l

10 to less than 15

e, f, g, n

Unprotected, Nonsprinklered (UP, NS)

15%

h

Unprotected, Sprinklered (UP, S)

i

45%

Protected (P)

45%

l

15 to less than 20

f, g, n

Unprotected, Nonsprinklered (UP, NS)

25%

Unprotected, Sprinklered (UP, S)

i

75%

Protected (P)

75%

l

20 to less than 25

f, g, n

Unprotected, Nonsprinklered (UP, NS)

45%

Unprotected, Sprinklered (UP, S)

i

No Limit

Protected (P)

No Limit

l

25 to less than 30

f, g, n

Unprotected, Nonsprinklered (UP, NS)

70%

Unprotected, Sprinklered (UP, S)

i

No Limit

Protected (P)

No Limit

30 or greater

Unprotected, Nonsprinklered (UP, NS)

No Limit

Unprotected, Sprinklered (UP, S)

i

No Limit

Protected (P)

No Limit

For SI: 1 foot = 304.8 mm.

UP, NS = Unprotected openings in buildings not equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

UP, S = Unprotected openings in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

P = Openings protected with an opening protective assembly in accordance with Section 705.8.2.

a. Values indicated are the percentage of the area of the exterior wall, per story.

b. For the requirements for fire walls of buildings with differing heights, see Section 706.6.

c. For openings in a fire wall for buildings on the same tax lot, see Section 706.8.

d. The maximum percentage of unprotected and protected openings shall be 25 percent for Group R-3 occupancies.

e. Unprotected openings shall not be permitted for openings with a fire separation distance of less than 15 feet for Group H-2 and H-3 occupancies.

f. The area of unprotected and protected openings for Group R-3 occupancies shall have no limit, if provided with a fire separation distance of 5 feet or greater.

g. The area of openings in an open parking structure with a fire separation distance of 10 feet or greater shall have no limit.

h. Includes buildings accessory to Group R-3.

i. Not applicable to Group H-1, H-2 and H-3 occupancies.

j. Protected openings through a wall or walls between buildings shall comply with Section 705.8.

k. Protected openings within a fire separation distance of 3 feet or less are permitted for Occupancy Groups R-2 and R-3 provided such openings do not exceed 10 percent of the area of the facade of the story in which they are located. These openings shall not be credited towards meeting any mandatory natural light or ventilation requirements unless they also comply with applicable provisions of Chapter 12 and the zoning resolution.

l. In Group R-2 and R-3 occupancies with an exterior separation distance greater than 3 feet, openings shall be in accordance with percentages indicated as "Protected Classification of Opening" in Table 705.8. However, such openings shall not be required to be protected.

m. Upon special application, the commissioner may permit exterior wall openings to be constructed in excess of the permitted area established by Table 705.8 provided that such openings are protected and provided that at the time of their construction they are located at least 60 feet in a direct line, measured at any angle, including vertically and horizontally, from any neighboring building, unless otherwise permitted by Section 705.3 for buildings on the same tax lot. The construction type of the neighboring building shall not be factored into the measurement of the distance between the openings and adjoining building. If any neighboring building is later altered or constructed to come within the above distance limitation, the affected exterior openings shall immediately be closed with construction meeting the fire-resistance rating requirements for exterior wall construction of the building in which they are located. Such additional openings shall not be credited toward meeting any of the mandatory natural light or ventilation requirements unless they also comply with applicable provisions of the New York City Zoning Resolution and Chapter 12 of this code.

n. The area of openings in a building containing only a Group U occupancy private garage or carport, with a fire separation distance of 5 feet (1524 mm) or greater, shall have no limit.

The maximum area of unprotected and protected openings permitted in an exterior wall in any story of a building shall not exceed the percentages specified in Table 705.8.

Exceptions:

1. In other than Group H occupancies, unlimited unprotected openings are permitted in the first story above grade plane either:

1.1. Where the wall faces a street and has a fire separation distance of more than 15 feet (4572 mm); or

1.2. Where the wall faces an unoccupied space, the unoccupied space shall be on the same tax lot or dedicated for public use, shall be not less than 30 feet (9144 mm) in width and shall have access from a street by a posted fire lane in accordance with the New York City Fire Code.

2. Buildings whose exterior bearing walls, exterior nonbearing walls and exterior primary structural frame are not required to be fire-resistance-rated shall be permitted to have unlimited unprotected openings.

705.8.2 Protected openings.

Where openings are required to be protected, fire doors and fire shutters shall comply with Section 716.5 and fire window assemblies shall comply with Section 716.6.

Exception: Opening protectives are not required where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 and the exterior openings are protected by a water curtain using automatic sprinklers approved for that use. The sprinklers and the water curtain shall be installed in accordance with NFPA 13, as modified by Appendix Q of this code.

705.8.3 Unprotected openings.

Where unprotected openings are permitted, windows and doors shall be constructed of any approved materials. Glazing shall conform to the requirements of Chapters 24 and 26.

705.8.4 Mixed openings.

Where both unprotected and protected openings are located in the exterior wall in any story of a building, the total area of the openings shall be determined in accordance with the following formula:

(A

p

 / a

p

) + (A

u

 / a

u

) £ 1

(Equation 7-2)

where:

A

p

= Actual area of protected openings, or the equivalent area of protected openings, A

e

(see Section 705.7).

a

p

= Allowable area of protected openings.

A

u

= Actual area of unprotected openings.

a

u

= Allowable area of unprotected openings.

705.8.5 Vertical separation of openings.

Openings in exterior walls in adjacent stories shall be separated vertically to protect against fire spread on the exterior of the buildings where the openings are within 5 feet (1524 mm) of each other horizontally. Such openings shall be separated vertically not less than 3 feet ( 914.4 mm) by spandrel girders, exterior walls or other similar assemblies that have a fire-resistance rating of not less than 1 hour, rated for exposure to fire from both sides, or by flame barriers that extend horizontally not less than 30 inches (762 mm) beyond the exterior wall and that are at least as wide as the opening. Flame barriers shall have a fire-resistance rating of not less than 1 hour. The unexposed surface temperature limitations specified in ASTM E 119 or UL 263 shall not apply to the flame barriers or vertical separation unless otherwise required by the provisions of this code. Where a curtain wall assembly is used on the exterior wall, the intersection between the floor assembly and curtain wall assembly shall be protected in accordance with Section 713.4 of this code.

Exceptions:

1. This section shall not apply to buildings that are three stories or less above grade plane.

2. This section shall not apply to buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2.

3. This section shall not apply to open parking garages.

4. This section shall not apply to Occupancy Group A, E, I or R.

5. This section shall not apply where the opening in the lower story is a protected opening with a fire protection rating of at least 3/4 hour.

705.8.6 Vertical exposure.

For buildings on the same tax lot, opening protectives shall be provided in every opening that is less than 15 feet (4572 mm) vertically above the roof of an adjacent building or structure based on assuming an imaginary line between them. The opening protectives are required where the fire separation distance between the imaginary line and the adjacent building or structure is less than 15 feet (4572 mm).

Exceptions:

1. Opening protectives are not required where the roof assembly of the adjacent building or structure has a fire-resistance rating of not less than 1 hour for a minimum distance of 10 feet (3048 mm) from the exterior wall facing the imaginary line and the entire length and span of the supporting elements for the fire-resistance-rated roof assembly has afire-resistance rating of not less than 1 hour.

2. Buildings on the same tax lot and considered as portions of one building in accordance with Section 705.3 are not required to comply with Section 705.8.6.

705.9 Joints.

Joints made in or between exterior walls required by this section to have a fire-resistance rating shall comply with Section 715.

Exception: Joints in exterior walls that are permitted to have unprotected openings.

705.9.1 Voids.

The void created at the intersection of a floor/ceiling assembly and an exterior curtain wall assembly shall be protected in accordance with Section 715.4.

705.10 Ducts and air transfer openings.

Penetrations by air ducts and air transfer openings in fire-resistance-rated exterior walls required to have protected openings shall comply with Section 717.

Exception: Foundation vents installed in accordance with this code are permitted.

705.11 Parapets.

Parapets shall be provided on exterior walls of buildings.

Exceptions: A parapet need not be provided on an exterior wall where any of the following conditions exist:

1. The wall is not required to be fire-resistance rated in accordance with Table 602 because of fire separation distance.

2. The building has an area of not more than 1,000 square feet (92.9 m

2

) on any floor.

3. Walls that terminate at roofs of not less than 2-hour fire-resistance-rated construction.

4. One-hour fire-resistance-rated exterior walls that terminate at the underside of the roof sheathing, deck or slab, provided that the entire building is covered with a Class A roof covering. Such roof shall not have openings located within 10 feet (3048 mm) of the 1-hour fire-resistance-rated exterior wall and not within 5 feet (1524 mm) for Groups R and U.

4.1. Where the roof/ceiling framing elements are parallel to the walls, such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction for a width of 4 feet (1220 mm) for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall.

4.2. Where roof/ceiling framing elements are not parallel to the wall, the entire span of such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction.

5. In occupancies of Groups R-2 and R-3, where both are provided with a Class A or B roof covering, the exterior wall shall be permitted to terminate at the underside of the roof sheathing or deck in Type III, IV and V construction, provided one or both of the following criteria is met:

5.1. The roof sheathing or deck is constructed of approved noncombustible materials or of fire-retardant-treated wood, for a distance of 4 feet (1220 mm) from the perimeter; or

5.2. The roof is protected with 0.625-inch (15.9 mm) Type X gypsum board directly beneath the underside of the roof sheathing or deck, supported by not less than nominal 2-inch (50.8 mm) ledgers attached to the sides of the roof framing members for a minimum distance of 4 feet (1220 mm).

6. Where the wall is permitted to have not less than 25 percent of the exterior wall areas containing unprotected openings based on fire separation distance as determined in accordance with Section 705.8.

705.11.1 Parapet construction.

Parapets shall have the same fire-resistance rating as that required for the supporting wall, and on any side adjacent to a roof surface, shall have noncombustible faces for the uppermost 18 inches (457.2 mm), including counterflashing and coping materials. The height of the parapet shall be not less than 30 inches (762 mm) above the point where the roof surface and the wall intersect. Where the roof slopes toward a parapet at a slope greater than two units vertical in 12 units horizontal (16.7-percent slope), the parapet shall extend to the same height as any portion of the roof within a fire separation distance where protection of wall openings is required, but in no case shall the height be less than 30 inches (762 mm).

705.12 Portions of a building cantilevered over existing buildings.

Where a portion of a building is cantilevered over an adjacent building or tax lot by a horizontal distance greater than 1 foot (304.8 mm), the cantilevered portions shall be protected with construction that conforms to a fire engineering analysis acceptable to the commissioner that conforms to Section 705.12.1. In no case shall the protection for structural elements and horizontal assemblies be less than that required by the building type of construction. In no case shall the fire-resistance rating of exterior walls or any other cantilevered exterior surfaces be less than that required by the building type of construction, and in no case shall the limitations for openings on such exterior surfaces be less than that required for a lot line condition pursuant to Table 705.8, including footnote "m".

705.12.1 Analysis.

The analysis shall demonstrate that all portions of the building that cantilever will withstand the anticipated effects of a design fire in accordance with generally accepted fire engineering principles with respect to at least all of the following building elements:

1. The structural supports and frame of the cantilevered portion of the building;

2. The underside projecting assemblies of the cantilevered portion of the building; and

3. The exterior walls and openings on all sides of the cantilevered portion of the building.

705.12.1.1 Criteria.

With respect to the design fire within the existing building over which the proposed building is cantilevered, the analysis shall include a scenario to burn-out, where any active fire suppression systems do not operate, the fire department does not intervene, all interior vertical compartmentation, including at the entrances to the stairways, has been removed, and the fuel loading exceeds what is normally expected for the current occupancy by a factor of safety acceptable to the commissioner. Where there is no existing building below the cantilever, or where the existing building below the cantilever is significantly underbuilt, the commissioner may require additional data and analysis.

705.12.2 Fire Department access to buildings and roofs.

The applicant shall submit to the department an approval from the Fire Department that the proposed cantilever complies with applicable provisions of the New York City Fire Code with respect to access to buildings and roofs.

705.12.3 Fire protection peer review.

A fire protection peer review of the analysis required by Sections 705.12.1 and 705.12.1.1 shall be submitted to the department for each such analysis.

705.12.3.1 Fire protection peer reviewer.

The fire protection peer review shall be performed by a qualified independent fire protection engineer who has been retained by or on behalf of the owner. The peer reviewer shall have relevant experience performing fire-engineering analyses.

705.12.3.2 Extent of fire protection peer review.

The fire protection peer reviewer shall review the fire engineering analysis and construction documents relevant to the analysis for general compliance with the applicable provisions of this code.

705.12.3.3 Fire protection peer review report.

The fire protection peer reviewer shall submit a report to the department stating that the fire engineering analysis conforms to the requirements of this code without exception.

705.12.3.4 Responsibility.

The responsibility for the fire engineering analysis shall comply with Sections 705.12.3.4.1 and 705.12.3.4.2.

705.12.3.4.1 Applicant of record.

The architect or engineer submitting the fire engineering analysis shall retain responsibility for the fire engineering analysis. The activities and reports of the fire protection peer reviewer shall not relieve the applicant of record of this responsibility.

705.12.3.4.2 Fire protection peer reviewer.

The fire protection peer reviewer's report shall state his or her opinion regarding the fire engineering analysis by the applicant of record.