Egress Requirements for Rooftops
Exits from structures are more common through doors that lead to a street or parking lot. However, being able to exit to the roof is useful in multi-story buildings, especially if the roof contains equipment that needs maintenance. In a pinch, leaving the building through the roof may be faster than going through a door, which may be further away. Local codes regulate building rooftop egress. Does this Spark an idea?
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Basics
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The International Building Code governs construction standards in the U.S. It states that a building with four or more stories above grade requires a stairway that reaches the roof. The number of stories counted does not include any basement levels. The roof must have a pitch that rises less than four units for every 12 units of horizontal movement, which is a 33 percent slope. It the roof is unoccupied, access can come from an alternating tread device. This is a structure with steps at 50 and 70 degrees from the horizontal that are attached to a center support. Because the steps alternate, users do not have both feet on the same plane at the same time.
Penthouse
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Stairways to a roof must exit through a penthouse. The term “penthouse,” in this case, does not refer to luxury rooftop accommodations. Instead, the structure is a shelters covering rooftop mechanical equipment or stairways. In Type 1 structures, which are constructed of concrete and steel, the height of the penthouse is unlimited. In other types of structures, the penthouse must be less than 18 feet above the roof deck, unless the penthouse houses tanks or elevators. In those cases, the maximum height is 28 feet above the roof deck.
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Specs
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The area of the penthouse cannot be more than one-third the area of the supporting roof deck, and it is not included in determining the building area or the number of stories. This structure requires protection from the elements through the use of louvers or flashing. Depending on the penthouse’s fire separation distance, which is defined as its distance from the property line, the type of building on which it rises, and the number of building stories, it may have a fire resistance rating ranging from one hour to less than an hour.
Hatches
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If the roof is unoccupied, access to the roof can be through a hatch or trap door that is at least 16 square feet, with a minimum dimension of 2 square feet. If that opening is within 10 feet of the roof edge, guards are needed. They must be at least 42 inches high and cannot allow a sphere 4 inches in diameter to pass through any of their openings up to a height of 36 inches. From 36 to 42 inches, the openings cannot allow a sphere 4.375 inches in diameter to pass. This prevents children from sticking their heads through such spaces.
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References
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