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C405.2.3.3 Toplight Daylight Zone
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The toplight daylight zone is the floor area underneath a roof fenestration assembly which complies with all of the following:
- The daylight zone shall extend laterally and longitudinally beyond the edge of the roof fenestration assembly to the nearest obstruction that is taller than 0.7 times the ceiling height, or up to 0.7 times the ceiling height, whichever is less, as indicated in Figure C405.2.3.3.
- No building or geological formation blocks direct sunlight from hitting the roof fenestration assembly at the peak solar angle on the summer solstice.
- Where located in existing buildings, the product of the visible transmittance of the roof fenestration assembly and the area of the rough opening of the roof fenestration assembly divided by the area of the daylight zone is not less than 0.008.

DAYLIGHT ZONE UNDER A ROOF FENESTRATION ASSEMBLY
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