Thickness of glass.
NYC Admin. Code § 27-646
in effect§ 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
Source: City of New York, Charter, Administrative Code and Rules (American Legal Publishing XML export, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCadmin/0-0-0-51168Fetched: 10/24/2026