User notes:
About this chapter: Chapter 24 establishes regulations for glass and glazing used in buildings and structures. Engineering and design requirements are included in the chapter for glazing that is subjected to wind and snow loads. Another concern of this chapter is glass and glazing used in areas where it is likely to be impacted by the occupants. Section 2406 identifies hazardous locations where glazing must either be safety glazing or protected to prevent impacts by occupants. Safety glazing must meet stringent standards and be appropriately marked or identified. Additional requirements are provided for glass and glazing in guards, handrails, elevator hoistways and elevator cars, as well as in athletic facilities.
Code development reminder: Code change proposals to this chapter will be considered by the IBC—Structural Code Development Committee during the 2019 (Group B) Code Development Cycle. See explanation on page iv.
Each pane shall bear the manufacturer's mark designating the type and thickness of the glass or glazing material. The identification shall not be omitted unless approved and an affidavit is furnished by the glazing contractor certifying that each light is glazed in accordance with approved construction documents that comply with the provisions of this chapter. Safety glazing shall be identified in accordance with Section 2406.3.
Each pane of tempered glass, except tempered spandrel glass, shall be permanently identified by the manufacturer. The identification mark shall be acid etched, sand blasted, ceramic fired, laser etched, embossed or of a type that, once applied, cannot be removed without being destroyed.
Tempered spandrel glass shall be provided with a removable paper marking by the manufacturer.
Float, wired and patterned glass in louvered windows and jalousies shall be not thinner than nominal 3/16 inch (4.8 mm) and not longer than 48 inches (1219 mm). Exposed glass edges shall be smooth.
Wired glass with wire exposed on longitudinal edges shall not be used in louvered windows or jalousies.
Where other glass types are used, the design shall be submitted to the building official for approval.
| where: | ||
| Fgw | = | Wind load on the glass due to basic design wind speed, V, computed in accordance with Section 1609. |
| Fga | = | Short duration load on the glass as determined in accordance with ASTM E1300. |
| where: | ||
| D | = | Glass dead load psf (kN/m2). |
| For glass sloped 30 degrees (0.52 rad) or less from horizontal, | = | 13 tg (For SI: 0.0245 tg). |
| For glass sloped more than 30 degrees (0.52 rad) from horizontal, | = | 13 tg cos θ (For SI: 0.0245 tg cos θ). |
| Fg | = | Total load, psf (kN/m2) on glass. |
| S | = | Snow load, psf (kN/m2) as determined in Section 1608. |
| tg | = | Total glass thickness, inches (mm) of glass panes and plies. |
| Wi | = | Inward wind force, psf (kN/m2) due to basic design wind speed, V, as calculated in Section 1609. |
| Wo | = | Outward wind force, psf (kN/m2) due to basic design wind speed, V, as calculated in Section 1609. |
| θ | = | Angle of slope from horizontal. |
The design of sloped glazing shall be based on Equation 24-5.
| where: | ||
| Fg | = | Total load on the glass as determined by Equations 24-2, 24-3 and 24-4. |
| Fga | = | Short duration load resistance of the glass as determined in accordance with ASTM E1300 for Equations 24-2 and 24-3; or the long duration load resistance of the glass as determined in accordance with ASTM E1300 for Equation 24-4. |
| where: | ||
| Fgw | = | Wind load on the glass due to basic design wind speed, V, computed in accordance with Section 1609. |
| Fge | = | Nonfactored load from ASTM E1300 using a thickness designation for monolithic glass that is not greater than the thickness of wired glass. |
Wired glass sloped more than 15 degrees (0.26 rad) from vertical in skylights, sun-spaces, sloped roofs and other exterior applications shall be designed to resist the most critical of the combinations of loads from Section 2404.2.
For Equations 24-2 and 24-3:
(Equation 24-7)
For Equation 24-4:
(Equation 24-8)
where:
Fg = Total load on the glass as determined by Equations 24-2, 24-3 and 24-4.
Fge = Nonfactored load in accordance with ASTM E1300.
| where: | ||
| Fgw | = | Wind load on the glass due to basic design wind speed, V, computed in accordance with Section 1609. |
| Fge | = | Nonfactored load in accordance with ASTM E1300. The value for patterned glass shall be based on the thinnest part of the glass. Interpolation between nonfactored load charts in ASTM E1300 shall be permitted. |
Patterned glass sloped more than 15 degrees (0.26 rad) from vertical in skylights, sunspaces, sloped roofs and other exterior applications shall be designed to resist the most critical of the combinations of loads from Section 2404.2.
For Equations 24-2 and 24-3:
(Equation 24-10)
For Equation 24-4:
(Equation 24-11)
where:
Fg = Total load on the glass as determined by Equations 24-2, 24-3 and 24-4.
Fge= Nonfactored load in accordance with ASTM E1300. The value for patterned glass shall be based on the thinnest part of the glass. Interpolation between the nonfactored load charts in ASTM E1300 shall be permitted.
| where: | ||
| Fg | = | Wind load on the glass due to basic design wind speed, V, computed in accordance with Section 1609. |
| Fge | = | Nonfactored load in accordance with ASTM E1300. The value for sandblasted glass is for moderate levels of sandblasting. |
Sloped glazing shall be any of the following materials, subject to the listed limitations.
- For monolithic glazing systems, the glazing material of the single light or layer shall be laminated glass with a minimum 30-mil (0.76 mm) polyvinyl butyral (or equivalent) interlayer, wired glass, light-transmitting plastic materials meeting the requirements of Section 2607, heat-strengthened glass or fully tempered glass.
- For multiple-layer glazing systems, each light or layer shall consist of any of the glazing materials specified in Item 1.
Annealed glass is permitted to be used as specified in Exceptions 2 and 3 of Section 2405.3.
For additional requirements for plastic skylights, see Section 2610. Glass-block construction shall conform to the requirements of Section 2110.1.
Where used in monolithic glazing systems, heat-strengthened and fully tempered glass shall have screens installed below the glazing material. The screens and their fastenings shall be: capable of supporting twice the weight of the glazing; firmly and substantially fastened to the framing members; and installed within 4 inches (102 mm) of the glass. The screens shall be constructed of a noncombustible material not thinner than No. 12 B&S gage (0.0808 inch) with mesh not larger than 1 inch by 1 inch (25 mm by 25 mm). In a corrosive atmosphere, structurally equivalent noncorrosive screen materials shall be used. Heat-strengthened glass, fully tempered glass and wired glass, where used in multiple-layer glazing systems as the bottom glass layer over the walking surface, shall be equipped with screening that conforms to the requirements for monolithic glazing systems.
Exception: In monolithic and multiple-layer sloped glazing systems, the following applies:
- Fully tempered glass installed without protective screens where glazed between intervening floors at a slope of 30 degrees (0.52 rad) or less from the vertical plane shall have the highest point of the glass 10 feet (3048 mm) or less above the walking surface.
- Screens are not required below any glazing material, including annealed glass, where the walking surface below the glazing material is permanently protected from the risk of falling glass or the area below the glazing material is not a walking surface.
- Any glazing material, including annealed glass, is permitted to be installed without screens in the sloped glazing systems of commercial or detached noncombustible greenhouses used exclusively for growing plants and not open to the public, provided that the height of the greenhouse at the ridge does not exceed 30 feet (9144 mm) above grade.
Screens shall not be required in individual dwelling units in Groups R-2, R-3 and R-4 where fully tempered glass is used as single glazing or as both panes in an insulating glass unit, and the following conditions are met:
Screens shall not be required for laminated glass with a 15-mil (0.38 mm) polyvinyl butyral (or equivalent) interlayer used in individual dwelling units in Groups R-2, R-3 and R-4 within the following limits:
In Type I and II construction, sloped glazing and skylight frames shall be constructed of noncombustible materials. In structures where acid fumes deleterious to metal are incidental to the use of the buildings, approved pressure-treated wood or other approved noncorrosive materials are permitted to be used for sash and frames. Framing supporting sloped glazing and skylights shall be designed to resist the tributary roof loads in Chapter 16. Skylights set at an angle of less than 45 degrees (0.79 rad) from the horizontal plane shall be mounted not less than 4 inches (102 mm) above the plane of the roof on a curb constructed as required for the frame. Skylights shall not be installed in the plane of the roof where the roof pitch is less than 45 degrees (0.79 rad) from the horizontal.
Exception: Installation of a skylight without a curb shall be permitted on roofs with a minimum slope of 14 degrees (three units vertical in 12 units horizontal) in Group R-3 occupancies. Unit skylights installed in a roof with a pitch flatter than 14 degrees (0.25 rad) shall be mounted not less than 4 inches (102 mm) above the plane of the roof on a curb constructed as required for the frame unless otherwise specified in the manufacturer's installation instructions.
The design of skylights shall be based on Equation 24-13.
(Equation 24-13)
where:
Fg = Maximum load on the skylight determined from Equations 24-2 through 24-4 in Section 2404.2.
PG = Performance grade rating of the skylight.
| where: | ||
| PGPos | = | Performance grade rating of the skylight under positive design pressure; |
| PGNeg | = | Performance grade rating of the skylight under negative design pressure; and |
Fgi and Fgo are determined in accordance with the following:
For 0.6Wo ≥ D,
| where: | ||
| Wo | = | Outward wind force, psf (kN/m2) due to basic design wind speed, V, as calculated in Section 1609. |
| D | = | The dead weight of the glazing, psf (kN/m2) as determined in Section 2404.2 for glass, or by the weight of the plastic, psf (kN/m2) for plastic glazing. |
| Fgi | = | Maximum load on the skylight determined from Equations 24-3 and 24-4 in Section 2404.2. |
| Fgo | = | Maximum load on the skylight determined from Equation 24-2. |
For 0.6 Wo < D,
| where: | ||
| Wo | = | The outward wind force, psf (kN/m2) due to basic design wind speed, V, as calculated in Section 1609. |
| D | = | The dead weight of the glazing, psf (kN/m2) as determined in Section 2404.2 for glass, or by the weight of the plastic for plastic glazing. |
| Fgi | = | Maximum load on the skylight determined from Equations 24-2 through 24-4 in Section 2404.2. |
| Fgo | = | 0. |
Where required by other sections of this code, glazing shall be tested in accordance with CPSC 16 CFR Part 1201. Glazing shall comply with the test criteria for Category II, unless otherwise indicated in Table 2406.2(1).
Exception: Glazing not in doors or enclosures for hot tubs, whirlpools, saunas, steam rooms, bathtubs and showers shall be permitted to be tested in accordance with ANSI Z97.1. Glazing shall comply with the test criteria for Class A, unless otherwise indicated in Table 2406.2(2).
MINIMUM CATEGORY CLASSIFICATION OF GLAZING USING CPSC 16 CFR PART 1201
| EXPOSED SURFACE AREA OF ONE SIDE OF ONE LITE | GLAZING IN STORM OR COMBINATION DOORS (Category class) | GLAZING IN DOORS (Category class) | GLAZED PANELS REGULATED BY SECTION 2406.4.3 (Category class) | GLAZED PANELS REGULATED BY SECTION 2406.4.2 (Category class) | DOORS AND ENCLOSURES REGULATED BY SECTION 2406.4.5 (Category class) | SLIDING GLASS DOORS PATIO TYPE (Category class) |
| 9 square feet or less | I | I | No requirement | I | II | II |
| More than 9 square feet | II | II | II | II | II | II |
For SI: 1 square foot = 0.0929 m2.
MINIMUM CATEGORY CLASSIFICATION OF GLAZING USING ANSI Z97.1
| EXPOSED SURFACE AREA OF ONE SIDE OF ONE LITE | GLAZED PANELS REGULATED BY SECTION 2406.4.3 (Category class) | GLAZED PANELS REGULATED BY SECTION 2406.4.2 (Category class) | DOORS AND ENCLOSURES REGULATED BY SECTION 2406.4.5a (Category class) |
| 9 square feet or less | No requirement | B | A |
| More than 9 square feet | A | A | A |
For SI: square foot = 0.0929 m2.
- Use is only permitted by the exception to Section 2406.2.
Except as indicated in Section 2406.3.1, each pane of safety glazing installed in hazardous locations shall be identified by a manufacturer's designation specifying who applied the designation, the manufacturer or installer and the safety glazing standard with which it complies, as well as the information specified in Section 2403.1. The designation shall be acid etched, sand blasted, ceramic fired, laser etched, embossed or of a type that once applied, cannot be removed without being destroyed. A label meeting the requirements of this section shall be permitted in lieu of the manufacturer's designation.
Exceptions:
- For other than tempered glass, manufacturer's designations are not required, provided that the building official approves the use of a certificate, affidavit or other evidence confirming compliance with this code.
- Tempered spandrel glass is permitted to be identified by the manufacturer with a removable paper designation.
Glazing in all fixed and operable panels of swinging, sliding and bifold doors shall be considered to be a hazardous location.
Exceptions:
- Glazed openings of a size through which a 3-inch-diameter (76 mm) sphere is unable to pass.
- Decorative glazing.
- Glazing materials used as curved glazed panels in revolving doors.
- Commercial refrigerated cabinet glazed doors.
Glazing in an individual fixed or operable panel adjacent to a door where the nearest vertical edge of the glazing is within a 24-inch (610 mm) arc of either vertical edge of the door in a closed position and where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) above the walking surface shall be considered to be a hazardous location.
Exceptions:
- Decorative glazing.
- Where there is an intervening wall or other permanent barrier between the door and glazing.
- Where access through the door is to a closet or storage area 3 feet (914 mm) or less in depth. Glazing in this application shall comply with Section 2406.4.3.
- Glazing in walls on the latch side of and perpendicular to the plane of the door in a closed position in one- and two-family dwellings or within dwelling units in Group R-2.
Glazing in an individual fixed or operable panel that meets all of the following conditions shall be considered to be a hazardous location:
- The exposed area of an individual pane is greater than 9 square feet (0.84 m2).
- The bottom edge of the glazing is less than 18 inches (457 mm) above the floor.
- The top edge of the glazing is greater than 36 inches (914 mm) above the floor.
- One or more walking surface(s) are within 36 inches (914 mm), measured horizontally and in a straight line, of the plane of the glazing.
Exceptions:
- Decorative glazing.
- Where a horizontal rail is installed on the accessible side(s) of the glazing 34 to 38 inches (864 to 965 mm) above the walking surface. The rail shall be capable of withstanding a horizontal load of 50 pounds per linear foot (730 N/m) without contacting the glass and be not less than 11/2 inches (38 mm) in cross-sectional height.
- Outboard panes in insulating glass units or multiple glazing where the bottom exposed edge of the glass is 25 feet (7620 mm) or more above any grade, roof, walking surface or other horizontal or sloped (within 45 degrees of horizontal) (0.79 rad) surface adjacent to the glass exterior.
Glazing in walls, enclosures or fences containing or facing hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, showers and indoor or outdoor swimming pools where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) measured vertically above any standing or walking surface shall be considered to be a hazardous location. This shall apply to single glazing and all panes in multiple glazing.
Exception: Glazing that is more than 60 inches (1524 mm), measured horizontally and in a straight line, from the water's edge of a bathtub, hot tub, spa, whirlpool or swimming pool.
Glazing adjacent to the landing at the bottom of a stairway where the glazing is less than 60 inches (1524 mm) above the landing and within a 60-inch (1524 mm) horizontal arc that is less than 180 degrees (3.14 rad) from the bottom tread nosing shall be considered to be a hazardous location.
Exception: Glazing that is protected by a guard complying with Sections 1015 and 1607.8 where the plane of the glass is greater than 18 inches (457 mm) from the guard.
Glass used in a handrail or a guard shall be laminated glass constructed of fully tempered or heat-strengthened glass and shall comply with Category II or CPSC 16 CFR Part 1201 or Class A of ANSI Z97.1. Glazing in railing in-fill panels shall be of an approved safety glazing material that conforms to the provisions of Section 2406.1.1. For all glazing types, the minimum nominal thickness shall be 1/4 inch (6.4 mm).
Exception: Single fully tempered glass complying with Category II of CPSC 16 CFR Part 1201 or Class A of ANSI Z97.1 shall be permitted to be used in handrails and guardrails where there is no walking surface beneath them or the walking surface is permanently protected from the risk of falling glass.
Guards with structural glass baluster panels shall be installed with an attached top rail or handrail. The top rail or handrail shall be supported by not fewer than three glass baluster panels, or shall be otherwise supported to remain in place should one glass baluster panel fail.
Exception: An attached top rail or handrail is not required where the glass baluster panels are laminated glass with two or more glass plies of equal thickness and of the same glass type. The panels shall be tested to remain in place as a barrier following impact or glass breakage in accordance with ASTM E2353.
Test methods and loads for individual glazed areas in racquetball and squash courts subject to impact loads shall conform to those of CPSC 16 CFR Part 1201 or ANSI Z97.1 with impacts being applied at a height of 59 inches (1499 mm) above the playing surface to an actual or simulated glass wall installation with fixtures, fittings and methods of assembly identical to those used in practice.
Glass walls shall comply with the following conditions:
- A glass wall in a racquetball or squash court, or similar use subject to impact loads, shall remain intact following a test impact.
- The deflection of such walls shall be not greater than 11/2 inches (38 mm) at the point of impact for a drop height of 48 inches (1219 mm).
Glass doors shall comply with the following conditions:
Glass in elevator car enclosures, glass elevator car doors and glass used for lining walls and ceilings of elevator cars shall be laminated glass conforming to Class A in accordance with ANSI Z97.1 or Category II in accordance with CPSC 16 CFR Part 1201.
Exception: Tempered glass shall be permitted to be used for lining walls and ceilings of elevator cars provided that:
- The glass is bonded to a nonpolymeric coating, sheeting or film backing having a physical integrity to hold the fragments when the glass breaks.
- The glass is not subjected to further treatment such as sandblasting; etching; heat treatment or painting that could alter the original properties of the glass.
- The glass is tested to the acceptance criteria for laminated glass as specified for Class A in accordance with ANSI Z97.1 or Category II in accordance with CPSC 16 CFR Part 1201.
