Section R318 — MEANS OF EGRESS

Dwelling units shall be provided with a means of egress in accordance with this section. The means of egress shall provide a continuous and unobstructed path of vertical and horizontal egress travel from all portions of the dwelling unit to the required egress door without requiring travel through a garage. The required egress door shall open directly into a public way or to a yard or court that opens to a public way.

Not less than one egress door shall be provided for each dwelling unit. The egress door shall be side-hinged, and shall provide a clear width of not less than 32 inches (813 mm) where measured between the face of the door and the stop, with the door open 90 degrees (1.57 rad). The clear height of the door opening shall be not less than 78 inches (1981 mm) in height measured from the top of the threshold to the bottom of the stop. Other doors shall not be required to comply with these minimum dimensions. Egress doors shall be readily openable from inside the dwelling unit without the use of a key or special knowledge or effort.

There shall be a landing or floor on each side of each exterior door. The width of each landing shall be not less than the door served. Landings shall have a dimension of not less than 36 inches (914 mm) measured in the direction of travel. The slope at exterior landings shall not exceed [1] / 4 unit vertical in 12 units horizontal (2 percent). Exception: Exterior balconies less than 60 square feet (5.6 m [2] ) and only accessed from a door are permitted to have a landing that is less than 36 inches (914 mm) measured in the direction of travel.

R318.3.1 Floor elevations at the required egress doors. Landings or finished floors at the required egress door shall be not more than 1 [1] / 2 inches (38 mm) lower than the top of the threshold. Exception: The landing or floor on the exterior side shall be not more than 7 [3] / 4 inches (196 mm) below the top of the threshold provided that the door does not swing over the landing or floor.

Where exterior landings or floors serving the required egress door are not at grade, they shall be provided with access to grade by means of a ramp in accordance with Section R318.8 or a stairway in accordance with Section R318.7.

R318.3.2 Floor elevations at other exterior doors. Exterior doors other than the required egress door shall be provided with landings or floors not more than 7 [3] / 4 inches (196 mm) below the top of the threshold.

Exception: An exterior landing or floor is not required at the exterior doorway where a stairway of not more than two risers is located on the exterior side of the door, provided that the door does not swing over the stairway.

R318.3.3 Storm and screen doors. Storm and screen doors shall be permitted to swing over exterior stairs and landings.

Egress from basements and habitable levels that are not provided with an egress door in accordance with Section R318.2 shall be by one or more ramps in accordance with Section R318.8 or one or more stairways in accordance with Section R318.7. For habitable levels or basements located more than one story above or more than one story below an egress door, the maxi- mum travel distance from any occupied point to a stairway or ramp that provides egress from such habitable level or basement, shall not exceed 50 feet (15 240 mm).

Exterior landings, decks, balconies, stairs and similar facilities shall be positively anchored to the primary structure to resist both vertical and lateral forces or shall be designed to be selfsupporting. Attachment shall not be accomplished by use of toenails or nails subject to withdrawal.

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Where required by this code or provided, stairways shall comply with this section.

Exceptions:

1. Stairways not within or serving a building, porch or deck.
2. Stairways leading to nonhabitable attics.
3. Stairways leading to crawl spaces.

R318.7.1 Width. Stairways shall be not less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. The clear width of stairways at and below the handrail height, including treads and landings, shall be not less than 31 [1] / 2 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are installed on both sides.

Exception: The width of spiral stairways shall be in accordance with Section R318.7.11.1.

R318.7.2 Headroom. The headroom in stairways shall be not less than 6 feet 8 inches (2032 mm) measured vertically from the sloped line adjoining the tread nosing or from the floor surface of the landing or platform on that portion of the stairway.

Exceptions:

1. Where the nosings of treads at the side of a flight extend under the edge of a floor opening through which the stair passes, the floor opening shall not project horizontally into the required headroom more than 4 [3] / 4 inches (121 mm).
2. The headroom for spiral stairways shall be in accordance with Section R318.7.11.1.

R318.7.3 Vertical rise. A flight of stairs shall not have a vertical rise greater than 12 feet 7 inches (3835 mm) between floor levels or landings.

R318.7.4 Walkline. The walkline across winder treads and landings shall be concentric to the turn and parallel to the direction of travel entering and exiting the turn. The walkline shall be located 12 inches (305 mm) from the inside of the turn. The 12-inch (305 mm) dimension shall be measured from the widest point of the clear stair width at the walking surface. Where winders are adjacent within a flight, the point of the widest clear stair width of the adjacent winders shall be used.

R318.7.5 Stair treads and risers. Stair treads and risers shall meet the requirements of this section. For the purposes of this section, dimensions and dimensioned surfaces shall be exclusive of carpets, rugs or runners. R318.7.5.1 Risers. The riser height shall be not more than 7 [3] / 4 inches (196 mm). The riser height shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than [3] / 8 inch (9.5 mm). Risers shall be vertical or sloped from the underside of the nosing of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. At open risers, openings located more than 30 inches (762 mm), as measured vertically, to the floor or grade below shall not permit the passage of a 4-inch-diameter (102 mm) sphere.

Exceptions:

1. The opening between adjacent treads is not limited on spiral stairways.
2. The riser height of spiral stairways shall be in accordance with Section R318.7.11.1.

R318.7.5.2 Treads. The tread depth shall be not less than 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread’s leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than [3] / 8 inch (9.5 mm).

R318.7.5.2.1 Winder treads. Winder treads shall have a tread depth of not less than 10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads shall have a tread depth of not less than 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than [3] / 8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and shall not be required to be within [3] / 8 inch (9.5 mm) of the rectangular tread depth.

Exception: The tread depth at spiral stairways shall be in accordance with Section R318.7.11.1. R318.7.5.3 Nosings. Treads, landings and floors of stairways shall have a radius of curvature at the nosing not greater than [9] / 16 inch (14 mm) or a bevel not greater than [1] / 2 inch (12.7 mm). A nosing projection not less than [3] / 4 inch (19 mm) and not more than 1 [1] / 4 inches (32 mm) shall be provided on stairways. The greatest nosing projection shall not exceed the smallest nosing projection by more than [3] / 8 inch (9.5 mm) within a flight of stairs and the landings at the top of the flight.

Exceptions:

1. A nosing projection is not required where the tread depth is not less than 11 inches (279 mm).
2. Where risers are open, the maximum nosing projection shall be permitted to exceed 1 [1] / 4 inches (32 mm).

R318.7.5.4 Exterior plastic composite stair treads. Plastic composite exterior stair treads shall comply with the provisions of this section and Section R507.2.2.

R318.7.6 Landings for stairways. There shall be a floor or landing at the top and bottom of each flight of stairs. The width perpendicular to the direction of travel shall be not less than the width of the flight served. For landings of shapes other than square or rectangular, the depth at the walk line and the total area shall be not less than that of a quarter circle with a radius equal

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to the required landing width. Where the stairway has a straight run, the depth in the direction of travel shall be not less than 36 inches (914 mm).

Exceptions:

1. The top landing of an interior stairway, including those in an enclosed garage, shall be permitted to be on the other side of a door located at the top of the stairway, provided that the door does not swing over the stairs.
2. At an enclosed garage, the top landing at the stair shall be permitted to be not more than 7 [3] / 4 inches (197 mm) below the top of the threshold.
3. At exterior doors, a top landing is not required for an exterior stairway of not more than two risers, provided that the door does not swing over the stairway.
4. Exterior stairways to grade with three or fewer risers serving a deck, porch or patio shall have a bottom landing width of not less than 36 inches (914 mm), provided that the stairway is not the required access to grade serving the required egress door.

R318.7.7 Stairway walking surface. The walking surface of treads and landings of stairways shall be sloped not steeper than 1 unit vertical in 48 units horizontal (2-percent slope).

Exception: Where the surface of a landing is required elsewhere in the code to drain surface water, the walking surface of the landing shall be sloped not steeper than 1 unit vertical in 20 units horizontal (5-percent slope) in the direction of travel.

R318.7.8 Handrails. Handrails shall be provided on not less than one side of each flight of stairs with four or more risers.

R318.7.9 Stairways in existing buildings. Alterations to existing stairs shall not be required to comply with the requirements of this code where the existing space and construction does not allow a reduction in pitch or slope.

R318.7.10 Illumination. Stairways shall be provided with illumination in accordance with Sections R325.6 and R325.7.

R318.7.11 Special stairways. Spiral stairways and bulkhead enclosure stairways shall comply with the requirements of Section R318.7 except as specified in Sections R318.7.11.1 and R318.7.11.2.

R318.7.11.1 Spiral stairways. The clear width at and below the handrails at spiral stairways shall be not less than 26 inches (660 mm) and the walkline radius shall be not greater than 24 [1] / 2 inches (622 mm). Each tread shall have a depth of not less than 6 [3] / 4 inches (171 mm) at the walkline. Treads shall be identical, and the rise shall be not more than 9 [1] / 2 inches (241 mm). Headroom shall be not less than 6 feet 6 inches (1982 mm).

R318.7.11.2 Bulkhead enclosure stairways. Stairways serving bulkhead enclosures, not part of the required building egress, providing access from the outside grade level to the basement shall be exempt from the requirements of Sections R318.3 and R318.7 where the height from the basement finished floor level to grade adjacent to the stairway is not more than 8 feet (2438 mm) and the grade level opening to the stairway is covered by a bulkhead enclosure with hinged doors or other approved

means.

R318.7.12 Alternating tread devices. Alternating tread devices shall not be used as an element of a means of egress. Alternating tread devices shall be permitted provided that a required means of egress stairway or ramp serves the same space at each adjoining level or where a means of egress is not required. The clear width at and below the handrails shall be not less than 20 inches (508 mm).

Exception: Alternating tread devices are allowed to be used as an element of a means of egress for lofts, mezzanines and similar areas of 200 gross square feet (18.6 m [2] ) or less where such devices do not provide exclusive access to a kitchen or bathroom.

R318.7.12.1 Treads of alternating tread devices. Alternating tread devices shall have a tread depth of not less than 5 inches (127 mm), a projected tread depth of not less than 8 [1] / 2 inches (216 mm), a tread width of not less than 7 inches (178 mm) and a riser height of not more than 9 [1] / 2 inches (241 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projections of adjacent treads. The riser height shall be measured vertically between the leading edges of adjacent treads. The riser height and tread depth provided shall result in an angle of ascent from the horizontal of between 50 and 70 degrees (0.87 and 1.22 rad). The initial tread of the device shall begin at the same elevation as the platform, landing or floor surface.

R318.7.12.2 Handrails of alternating tread devices. Handrails shall be provided on both sides of alternating tread devices and shall comply with Section R320.

R318.7.13 Ship’s ladders. Ship’s ladders shall not be used as an element of a means of egress. Ship’s ladders shall be permitted provided that a required means of egress stairway or ramp serves the same space at each adjoining level or where a means of egress is not required. The clear width at and below the handrails shall be not less than 20 inches (508 mm).

Exception: Ship’s ladders are allowed to be used as an element of a means of egress for lofts, mezzanines and similar areas of 200 gross square feet (18.6 m [2] ) or less that do not provide exclusive access to a kitchen or bathroom.

R318.7.13.1 Treads of ship’s ladders. Treads shall have a depth of not less than 5 inches (127 mm). The tread shall be projected such that the total of the tread depth plus the nosing projection is not less than 8 [1] / 2 inches (216 mm). The riser height shall be not more than 9 [1] / 2 inches (241 mm).

R318.7.13.2 Handrails of ship’s ladders. Handrails shall be provided on both sides of ship’s ladders and shall comply with Section R320.

Where required by this code or provided, ramps shall comply with this section.

Exception: Ramps not within or serving a building, porch or deck.

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R318.8.1 Maximum slope. Ramps serving the egress door required by Section R318.2 shall have a slope of not more than 1 unit vertical in 12 units horizontal (8.3-percent slope).

Other ramps shall have a slope of not more than 1 unit vertical in 8 units horizontal (12.5 percent).

Exception: Where it is technically infeasible to comply because of site constraints, ramps shall have a slope of not more than 1 unit vertical in 8 units horizontal (12.5 percent).

R318.8.2 Landings required. There shall be a floor or landing at the top and bottom of each ramp, where doors open onto ramps, and where ramps change directions. The width of the landing perpendicular to the ramp slope shall be not less than the width of the ramp. The depth of the landing in the direction of the ramp slope shall be not less than 36 inches (914 mm).

R318.8.3 Handrails required. Handrails shall be provided on not less than one side of ramps exceeding a slope of 1 unit vertical in 12 units horizontal (8.33-percent slope) and shall comply with Section R320.