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SECTION 311 MEANS OF EGRESS

311.1 General.


Stairways, ramps, exterior exit balconies, hallways and doors shall comply with this section.

311.2 Construction.


311.2.1 Attachment.


Required exterior exit balconies, stairs and similar exit facilities shall be positively anchored to the primary structure to resist both vertical and lateral forces. Such attachment shall not be accomplished by use of toenails or nails subject to withdrawal.

311.2.2 Under stair protection.


Enclosed accessible space under stairs shall have walls, under stair surface and any soffits protected on the enclosed side with ½-inch (12.7 mm) gypsum board.

311.3 Hallways.


The minimum width of a hallway shall be not less than 3 feet (914 mm).

311.4 Doors.


311.4.1 Exit door required.


Not less than one exit door conforming to this section shall be provided for each dwelling unit. The required exit door shall provide for direct access from the habitable portions of the dwelling to the exterior without requiring travel through a garage. Access to habitable levels not having an exit in accordance with this section shall be by a ramp in accordance with Section 311.6 or a stairway in accordance with Section 311.5.

311.4.2 Door type and size.


The required exit door shall be a side-hinged door not less than 3 feet (914 mm) in width and 6 feet 8 inches (2032 mm) in height. Other doors shall not be required to comply with these minimum dimensions.

311.4.2.1 Interior doors.


Interior doors to habitable rooms and basement stairs shall be a minimum 2 feet 6 inches (760 mm) wide and 6 feet 8 inches (2032 mm) in height. Bathroom doors shall be a minimum of 2 feet 4 inches (709 mm) wide and 6 feet 8 inches (2032 mm) in height.


Exception:
For half baths.

311.4.2.2 Garage access door.


A side hinged door not less than 2 feet 6 inches (760 mm) and 6 feet 8 inches (2032 mm) in height shall be required from all garages. A door between an attached garage and a dwelling shall be acceptable as meeting the requirements of this code.


311.4.3 Landings at doors.


There shall be a floor or landing on each side of each exterior door.


Exception:
Where a stairway of two or fewer risers is located on the exterior side of a door, other than the required exit door, a landing is not required for the exterior side of the door.

The floor or landing at the exit door required by Section 311.4.1 shall not be more than 1.5 inches (38 mm) lower than the top of the threshold. The floor or landing at exterior doors other than the exit door required by Section 311.4.1 shall not be required to comply with this requirement but shall have a rise no greater than that permitted in Section 311.5.3.

Exception:
The landing at the exterior doorway shall not be more than 8 1/4 inches (210 mm) below the top of the threshold, provided the door, other than an exterior storm or screen door, does not swing over the landing.

The width of each landing shall not be less than the door served. Every landing shall have a minimum dimension of 36 inches (914 mm) measured in the direction of travel.

311.4.4 Type of lock or latch.


All egress doors shall be readily openable from the side from which egress is to be made without the use of a key or special knowledge or effort.

311.5 Stairways.


311.5.1 Width.


Stairways shall not be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. Handrails shall not project more than 4.5 inches (114 mm) on either side of the stairway and the minimum clear width of the stairway at and below the handrail height, including treads and landings, shall not be less than 31.5 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are provided on both sides.

Exception:
The width of spiral stairways shall be in accordance with Section 311.5.8.

311.5.2 Headroom.


The minimum headroom in all parts of the stairway shall not be less than 6 feet 8 inches (2036 mm) measured vertically from the sloped plane adjoining the tread nosing or from the floor surface of the landing or platform.

311.5.3 Stair treads and risers.


311.5.3.1 Riser height.


The maximum riser height shall be inches (210 mm). The riser 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).

311.5.3.2 Tread depth.


The minimum tread depth shall be 9 inches (229 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). Winder treads shall have a minimum tread depth of 9 inches (229 mm) measured as above at a point 12 inches (305 mm) from the side where the treads are narrower. Winder treads shall have a minimum tread depth of 6 inches (152 mm) at any point. Within any flight of stairs, the greatest winder tread depth at the 12 inch (305 mm) walk line shall not exceed the smallest by more than 3/8 inch (9.5 mm).

311.5.3.3 Profile.


The radius of curvature at the leading edge of the tread shall be no greater than 9/16 inch (14.3 mm). A nosing not less than ¾ inch (19 mm) but not more than 1¼ inch (32 mm) shall be provided on stairways with solid risers. The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings. Beveling of nosing shall not exceed ½ inch (12.7 mm). Risers shall be vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 (0.51 rad) degrees from the vertical. Open risers are permitted, provided that the opening between treads does not permit the passage of a 4-inch diameter (102 mm) sphere.

Exceptions:


1.   A nosing is not required where the tread depth is a minimum of 11 inches (279 mm).

2.   The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less.

311.5.4 Landings for stairways.


There shall be a floor or landing at the top and bottom of each stairway.

Exception:
A floor or landing is not required at the top of an interior flight of stairs, provided a door does not swing over the stairs.

A flight of stairs shall not have a vertical rise greater than 12 feet (3658 mm) between floor levels or landings.

The width of each landing shall not be less than the stairway served. Every landing shall have a minimum dimension of 36 inches (914 mm) measured in the direction of travel.

311.5.5 Stairway walking surface.


The walking surface of treads and landings of stairways shall be sloped no steeper than one unit vertical in 48 inches horizontal (2-percent slope).

311.5.6 Handrails.


Handrails shall be provided on at least one side of each continuous run of treads or flight with four or more risers.

311.5.6.1 Height.


Handrail height, measured vertically from the sloped plane adjoining the tread nosing, or finish surface of ramp slope, shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm).

311.5.6.2 Continuity.


Handrails for stairways shall be continuous for the full length of the flight, from a point directly above the top riser of the flight to a point directly above lowest riser of the flight. Handrail ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall shall have a space of not less than 1½ inch (38 mm) between the wall and the handrails.

Exceptions:


1.   Handrails shall be permitted to be interrupted by a newel post at the turn.

2.   The use of a volute, turnout, starting easing or starting newel shall be allowed over the lowest tread.

3.
   Two or more separate rails shall be considered continuous if the termination of the rails occur over a single tread and within 4 inches (101.6 mm) of each other. If transitioning between a wall-mounted handrail and a guardrail/handrail, the wall-mounted rail must return into the wall.

311.5.6.3 Handrail grip size.


All required handrails shall be of one of the following types or provide equivalent graspability.

1.   Type I. Handrails with a circular cross section shall have an outside diameter of at least 1¼ inches (32 mm) and not greater than 2 inches (51 mm). If the handrail is not circular it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6¼ inches (160 mm) with a maximum cross section of dimension of 2¼ inches(57 mm).

2.   Type II. Handrails with a perimeter greater than 6½ inches (160 mm) shall provide a graspable finger recess area on both sides of the profile. The finger recess shall begin within a distance of ¾ inch (19 mm) measured vertically from the tallest portion of the profile and achieve a depth of at least 5/16 inch (8 mm) within 7/8 inch (22 mm) below the widest portion of the profile. This required depth shall continue for at least 3/8 inch (10 mm) to a level that is not less than 1¾ inches (45 mm) below the tallest portion of the profile. The minimum width of the handrail above the recess shall be 1¼ inches (32 mm) to a maximum of 2¾ inches (70 mm). Edges shall have a minimum radius of 0.01 inches (0.25 mm).

311.5.7 Illumination.


All stairs shall be provided with illumination in accordance with Section 303.6.

311.5.8 Special stairways.


Circular stairways, spiral stairways, winders and bulkhead enclosure stairways shall comply with all requirements of Section 311.5 except as specified below.

311.5.8.1 Spiral stairways.


Spiral stairways are permitted, provided the minimum width shall be 26 inches (660 mm) with each tread having a 7½-inches (190 mm) minimum tread depth at 12 inches from the narrower edge. All treads shall be identical, and the rise shall be no more than 9½ inches (241 mm). A minimum headroom of 6 feet 6 inches (1982 mm) shall be provided.

311.5.8.2 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 311.4.3 and 311.5 where the maximum height from the basement finished floor level to grade adjacent to the stairway does not exceed 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.

311.6 Ramps.


311.6.1 Maximum slope.


Ramps shall have a maximum slope of one unit vertical in eight units horizontal (12.5-percent slope).

311.6.2 Landings required.


A minimum 3-foot-by-3-foot (914 mm by 914 mm) landing shall be provided:

1.   At the top and bottom of ramps,

2.   Where doors open onto ramps,

3.   Where ramps change direction.

311.6.3 Handrails required.


Handrails shall be provided on at least one side of all ramps exceeding a slope of one unit vertical in 12 units horizontal (8.33-percent slope).

311.6.3.1 Height.


Handrail height, measured above the finished surface of the ramp slope, shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm).

311.6.3.2 Handrail grip size.


Handrails on ramps shall comply with Section 311.5.6.3.

311.6.3.3 Continuity.


Handrails where required on ramps shall be continuous for the full length of the ramp. Handrail ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall shall have a space of not less than 1.5 inches (38 mm) between the wall and the handrails.