The transport height is measured as a vertical distance between the curves of the profile. The tread depth is measured horizontally, between the vertical planes of the main projection of the adjacent treads and perpendicular to the leading edge of the tread. The measurement of the climb height and tread depth should represent the actual space available to those using the stairs. It cannot contain any part of the tread that is not available for someone to place their foot. Laying flooring on existing stairs can also reduce the space available for use on stairs. Exterior stairs have special requirements and considerations for design and construction. The International Residential Code (IRC) and the International Building Code (IBC) set the standards for exterior staircases. Building regulations for exterior stairs specify criteria for the design, use, location and construction of exterior stairs. Understanding the requirements of the exterior staircase code helps ensure a safe and durable staircase for outdoor use. Exterior stairs have special requirements for construction and design. IBC, IRC and ADA building codes help ensure that exterior stairs are designed, used and constructed safely and appropriately. IBC defines an external exit staircase as an output component that serves to meet one or more requirements for the exit structure, such as the required number of exits or distance to the exit, and is open to courtyards, courts or public roads. External stairs shall conform to the stairs and risers of IBC article 1011.5.
The height of stair ladders must be a maximum of 7 inches and a minimum of 4 inches. Section 1027.4 of the IBC states that open areas adjacent to external stairs or exit ramps must be courtyards, tribunals or public roads. The remaining sides can be surrounded by the exterior walls of the building. Composite floor coverings used for bearings shall comply with the provisions of section R507.2.2. In accordance with R507.2.2.3, deck boards, stairs, guards and handrails made of plastic composite materials containing wood, cellulose or other biodegradable materials shall be resistant to rot in accordance with ASTM D7032. The IRC and IBC determine the requirements for the exterior staircase code. The IRC defines the exterior staircase code for single-family and two-family homes and townhouses that are no more than three storeys above the level. IBC deals with the external exit staircase code for commercial, multi-family buildings not covered by IRC and industrial buildings. IBC Section 1027.2 states that external exit stairs may not be used as part of a starting medium required for group I-2 occupancy (24-hour medical care facilities). For occupancy in areas other than Group I-2, exterior stairs and exit ramps are permitted as part of a prescribed means of exit for buildings that must not exceed six storeys above the level or that are not high-rise buildings.
Section 1027.6 states that exterior stairs and exit ramps must be separated from the interior of the building in accordance with section 1023.2. Openings should be limited to normally occupied rooms. Section R311.5 states that exterior stairs, decks, balconies, stairs and similar facilities must be positively anchored to the primary structure to withstand vertical and lateral forces, or that they must be designed to be self-supporting. Fixation is not done using toenails or removal nails. An exterior exit staircase is an exit staircase that is open to the outside and leads directly to the outside. These can be prefabricated metal exterior stairs, concrete stairs, wooden stairs or any other type of construction. IBC section 1009, Requirements for Accessible Exit Devices, allows an external staircase serving levels other than the outlet discharge level to be part of an accessible means of exit. Section R311.7.8.6 states that plastic composite handrails shall comply with the requirements of section R507.2.2, which require plastic composite handrails to comply with the requirements of ASTM D7032. Section R507.2.2 requires that exterior deck panels, stair steps, guards and plastic composite handrails comply with the requirements of ASTM D7032. All stairs that serve as a mandatory means of exit must be permanently fixed (except in the case of stairs that serve as seats designed for repositioning, such as in theatres where sections of seating are added, removed or installed and where it is not practical for the stairs connected to these seats to be of solid and permanent construction). In buildings that are to be constructed in accordance with NFPA 101, Type I or Type II Human Safety Code, every staircase, platform and landing, without existing handrails or stairs, must be made of non-combustible materials everywhere.
Stairs may be flammable if the building is not required for this occupation to be constructed of Type I or Type II. For example, an occupation may not have requirements regarding the minimum type of construction of the building, or the occupancy chapter may permit Type III, Type IV or Type V construction. If the building is to be constructed of Type I or Type II, the materials used for the construction of new stairs (stairs, platforms and landings) must not be flammable. In addition, in accordance with section R311.7.5.4, exterior stairs made of plastic composites must comply with the provisions of this section and clause R507.2.2, which states that exterior deck panels, stair steps, guards and handrails made of plastic composite must comply with the requirements of ASTM D7032 and this section. Section R311 also refers to IRC Section R507.2.2, which defines requirements for exterior deck boards, stair steps, guards and plastic composite handrails. The ADA Accessibility Standards and IBC requirements for accessible exit lanes apply to external and interior stairs that are part of a required starting device. These include external stairs that are part of the exit discharge (i.e. the path from an exit to a public road such as a street or alley). IBC section 1009, Requirements for Accessible Exit Devices, allows an external staircase serving levels other than the outlet discharge level to be part of an accessible means of exit. Section 1011.7.2 of the IBC states that exterior stairs and external access to stairs must be designed in such a way that water does not accumulate on the aisles.
Stairs and landings should also be free of protrusions or lips that stair users could trip. The risk of tripping occurs especially when someone goes down the stairs, where the tread tread has projections. Installing a surface-mounted stair nose or material strip on an existing stair tread can result in a projection that presents a tripping hazard. Stepper screws that protrude from adjacent treads can also present a tripping hazard. (Other considerations to minimize tripping risks to accessibility are also addressed in CCI A117.1, Accessible and Usable Buildings and Facilities.) Stairs and landings within the same staircase must have uniform surface traction. This means that the slip resistance is reasonably uniform and sufficient to minimize the risk of slipping on the treads. Consistency is important because deceiving a person`s expectations as to the surface they will walk on is a major factor in missteps and falls that involve sliding. Materials used for floors that are acceptable as non-slip generally provide sufficient slip resistance when used for stairs. When stairs are wet, there is also an increased risk of slipping, just as there is an increased risk of slipping on wet floors made of similar materials. The IBC requirements for the landing code for external stairs are also found in section 1011.7.2 of the IBC as part of the external stair tread. Exterior stair railings must comply with all the general requirements of section R312.1 of the IRC protectors.
Section 1027.5 of the IBC states that stairs and exterior ramps must have a minimum distance of 10 feet, measured perpendicular to the outer edge of stairs or ramps, including landings to: adjacent property lines, other parts of the building, other buildings on the same property, unless adjacent exterior walls and building openings are protected in accordance with section 705 based on the fire distance.