Code of Massachusetts Regulations
780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
Chapter 24 - Glass and Glazing
Section 2405 - SLOPED GLAZING AND SKYLIGHTS
Subsection 2405.5 - Unit skylights
Current through Register 1531, September 27, 2024
Unit skylights shall be tested and labeled as complying with AAMA/WDMA/CSA 101/ I.S.2/A440. The label shall state the name of the manufacturer, the approved labeling agency, the product designation and the performance grade rating as specified in AAMA/WDMA/CSA 101/I.S.2/A440. If the product manufacturer has chosen to have the performance grade of the skylight rated separately for positive and negative design pressure, then the label shall state both performance grade ratings as specified in AAMA/WDMA/CSA 101/I.S.2/A440 and the skylight shall comply with Section 2405.5.2. If the skylight is not rated separately for positive and negative pressure, then the performance grade rating shown on the label shall be the performance grade rating determined in accordance with AAMA/WDMA/CSA 101/I.S.2/A440 for both positive and negative design pressure and the skylight shall conform to Section 2405.5.1.
2405.5.1 Unit skylights rated for the same performance grade for both positive and negative design pressure. The design of unit skylights shall be based on the following equation:
| Fg <= PG | (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.
2405.5.2 Unit skylights rated for separate performance grades for positive and negative design pressure. The design of unit skylights rated for performance grade for both positive and negative design pressures shall be based on the following equations:
| Fgi <= PGPos | (Equation 24-14) |
| Fgo <= PGNeg | (Equation 24-15) |
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 Wo >= D,
where:
Wo = Outward wind force, psf (kN/m2) 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 Wo < D,
where:
Wo = Is the outward wind force, psf (kN/m2) 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.
