N.Y.C. Admin. Code § 27-646: § 27-646 Thickness of glass.

Thicknesses of glass panels shall be chosen either on the basis of statistical probability of breakage (subdivision (a) of this section) or on the basis of table 10-7, at the designer's option.

(a) Statistical probability. Thickness of glass panels shall be chosen so that the statistical probability of breakage when the glass is initially subjected to the design wind load specified in table RS 9-5-1 does not exceed the values indicated in table 10-6. Probability or load factors used for design shall be derived by test. The sufficiency and validity of such test data shall be subject to approval by the commissioner.

(b) Alternate requirements. Alternative to the requirements of paragraph (a) above, the thickness of glass panels may be chosen from table 10-7. For glass with assured minimum thickness greater than required by reference standard RS 10-68, the maximum areas in table 10-7 may be increased in proportion to the assured minimum thickness.

TABLE 10-6 Probability of Breakage for Glass Panels (Based on Coefficient of Variation of 25%)

Elevation Above Grade of Mid-Point of Glass

Area of Panel – Sq. Ft.

0-50-Ft

0-60

60-80

80-100

100-120

120+

0-50

1.0%

1.0%

1.0%

1.0%

1.0%

50 or more

1.0%

0.8%

0.6%

0.4%

0.2%

TABLE 10-7 Maximum Area of Glass – Sq. Ft.

Nominal Thickness of Glass – Inches

Elevation Above Grade of Mid-Point of Glass – Ft.

0-50

50-300

300-600

600+

Sheet Glass

Single strength

9

9

8

7

Double strength

13

13

11

10

3/16"

25

25

21

19

7/32"

32

32

27

24

Plate and Float Glass

13/64"

25

25

21

19

1/4"

37

37

32

28

5/16"

54

54

46

40

3/8"

78

74

63

58

1/2"

114

100

86

75

5/8"

152

120

103

90

3/4"

210

137

118

103

7/8"

241

158

135

118

1"

312

204

175

153