Glass sloped more than 15 degrees (0.26 rad) from vertical in skylights, sunrooms, sloped roofs and other exterior applications shall be designed to resist the most critical of the following combinations of loads.
| Fg = 0.6Wo— D | (Equation 24-2) |
| Fg= 0.6Wi + D + 0.5 S | (Equation 24-3) |
| Fg= 0.3Wi + D + S | (Equation 24-4) |
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 ). | |
| Fg | = | Total load, psf (kN/m2) on glass. |
| S | = | Snow load, psf (kN/m2) as determined in Section1608. |
| tg | = | Total glass thickness, inches (mm) of glass panes and plies. |
| Wi | = | Inward wind force, psf (kN/m2) due to ultimate design wind speed, Vult, as calculated in Section 1609. |
| Wo | = | Outward wind force, psf (kN/m2) due to ultimate design wind speed, Vult, as calculated in Section 1609. |
| θ | = | Angle of slope from horizontal. |
Exception: The design pressure rating of unit skylights and tubular daylighting devices shall be determined in accordance with Section 2405.5.
The design of sloped glazing shall be based on the following equation:
| Fg≤Fga | (Equation 24-5) |
where:
| Fg | = | Total load on the glass determined from the load combinations above. |
| Fga | = | Short duration load resistance of the glass as determined according to ASTM E 1300 for Equations 24-2 and24-3; or the long duration load resistance of the glass as determined according to ASTM E 1300 for Equation24-4. |