N.Y.C. Admin. Code § BC 2109: Section BC 2109: Empirical Design of Masonry

2109.1 General.

Empirically designed masonry shall conform to this chapter or the requirements of Appendix A of TMS 402, except where otherwise noted in this section.

2109.1.1 Limitations.

The use of empirical design of masonry shall be limited as noted in Section A.1.2 of TMS 402. The use of dry-stacked, surface-bonded masonry shall be prohibited in Risk Category IV structures. In buildings that exceed one or more of the limitations of Section A.1.2 of TMS 402, masonry shall be designed in accordance with the engineered design provisions of Section 2101.2 or the foundation wall provisions of Section 1807.

2109.1.1.1 TMS 402, Section A.1.2.3, Wind.

Section A.1.2.3 of TMS 402 shall be modified as follows:

A.1.2.3 – Wind. Empirical requirements shall not apply to the design or construction of masonry for buildings, parts of buildings, or other structures to be located in areas where V

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as determined in accordance with Section 1609.3.1 of the New York City Building Code exceeds 110 mph.

2109.2 Surface-bonded walls.

Dry-stacked, surface-bonded concrete masonry walls shall comply with the requirements of Appendix A of TMS 402, except where otherwise noted in this section.

2109.2.1 Strength.

Dry-stacked, surface-bonded concrete masonry walls shall be of adequate strength and proportions to support all superimposed loads without exceeding the allowable stresses listed in Table 2109.2.1. Allowable stresses not specified in Table 2109.2.1 shall comply with the requirements of TMS 402.

Table 2109.2.1 Allowable Stress Gross Cross-Sectional Area for Dry-Stacked, Surface-Bonded Concrete Masonry Walls

Description

Maximum Allowable Stress (psi)

Compression standard block

45

Flexural tension

Horizontal span

30

Vertical span

18

Shear

10

For SI: 1 pound per square inch = 0.006895 Mpa.

2109.2.2 Construction.

Construction of dry-stacked, surface-bonded masonry walls, including stacking and leveling of units, mixing and application of mortar and curing and protection shall comply with ASTM C 946.

2109.3 Reserved.

2109.4 Thickness of masonry.

Minimum thickness requirements shall be based on nominal dimensions of masonry.

2109.4.1 Thickness of walls.

The thickness of masonry walls shall conform to the requirements of Section 2109.4.

2109.4.2 Minimum thickness.

The minimum thickness of masonry bearing walls more than one story high shall be 8 inches (203 mm) where the height floor to floor does not exceed 12 feet (3658 mm), the floor live load does not exceed 60 pounds per square foot (psf) (0.156 kg/m

2

), and the roof is designed so that the dead load imparts no lateral thrust to the wall. Bearing walls of one-story buildings shall not be less than 6 inches (152 mm) thick. However, the overall thickness of cavity or masonry-bonded hollow walls shall not be less than 8 inches (203 mm), including cavity.

2109.4.2.1 Walls above roof level.

Masonry walls above roof level, 12 feet (3658 mm) or less in height, enclosing stairways, machinery rooms, shafts, or penthouses, may be up to 8 inches (203 mm) thick and shall be considered as neither increasing the height nor requiring any increase in the thickness of the wall below.

2109.4.3 Partitions.

The minimum thickness for partitions shall be as follows:

Table 2109.4.3 Minimum Thickness of Masonry Partitions

Height of Walls

Thickness

8 ft. and under

2 in.

Over 8 ft. to 12 ft.

3 in.

Over 12 ft. to 16 ft.

4 in.

Over 16 ft. to 20 ft.

6 in.

Over 20 ft. to 24 ft.

8 in.

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

2109.5 Horizontal joints.

All concrete framed buildings to be constructed over 35 feet (10 668 mm) in height (as measured from adjoining grade to the main roof level), whose exterior wythe are of cavity wall construction with steel lintels, shall have horizontal joints in the exterior wythe to prevent masonry distress induced by vertical shortening of the structural frame.

2109.5.1 Joint minimum thickness.

Unless substantiated as indicated by 2109.5.2, horizontal joints shall be 1/4 inch (6.4 mm) minimum thickness, with neoprene, polyethylene, or urethane gasket or equivalent joint filler filling the entire joint, except for a recess from the toe of the lintel angle to the exterior of the facing brick, to provide space for caulking. These joints shall be placed at each floor.

2109.5.2 Joint thickness by analysis.

The applicant of record shall submit an engineering analysis establishing that proposed building horizontal joints spaced further apart than in 2109.5.1 are sufficient to provide for the effects of vertical shortening of the structural frame.