Yep, great point. And if you get technical and start measuring, I would suspect on these stairs you would find one or more exceeding 30 inches in height from grade within 36 inches horizontally.
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However there is the exception…
- On stairways with solid risers, there should be a nosing at least ¾ of an inch and not more than 1 and ¼ inches.
- The radius of a nosing curve should be no greater than 9/16 of an inch.
- A nosing is not required when the tread depth is 11 inches or more.
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Exterior Stair Code Requirements {Residential & Commercial}.
Exterior stair riser code
Exterior stair risers must comply with IBC section 1011.5 stair treads and risers. Stair risers height shall be 7 inches maximum and 4 inches minimum.
2018 IRC code for exterior stairs
The 2018 IRC code for exterior stairs is found in Section R311 Means of Egress. This section includes all the requirements for stairways including the specific requirements for exterior stairs.
Section R311 also refers to IRC section R507.2.2, which defines the requirements for outdoor plastic composite deck boards, stair treads, guards, and handrails.
Section R507.2.2 requires that plastic composite exterior deck boards, stair treads, guards, and handrails comply with the requirements of ASTM D7032.
Section R507.2.2.1 requires that plastic composite deck boards, stair treads, guardrails, handrails or their packaging shall bear a label that indicates compliance with ASTM D7032 and includes the allowable load and maximum allowable span determined in accordance with ASTM D7032.
Section R507.2.2.2 requires that plastic composite deck boards, stair treads, guards, and handrails shall exhibit a flame spread index not exceeding 200 when tested in accordance with ASTM E85 or UL 723 with the test specimen remaining in place during the test; except for plastic composites determined to be noncombustible.
Section R507.2.2.3 requires that plastic composite deck boards, stair treads, guards, and handrails containing wood, cellulosic or other biodegradable materials shall be decay resistant in accordance with ASTM D7032.
Section R507.2.2.4 requires that plastic composite deck boards, stair treads, guards, and handrails containing wood, cellulosic or other biodegradable materials shall be termite resistant in accordance with ASTM D7032.
Section R507.2.2.5 requires that plastic composite deck boards, stair treads, guards, and handrails shall be installed in accordance with this code and the manufacturer’s instructions.
Outdoor stair anchoring code
Section R311.5 states that 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 self-supporting. Attachment shall not be accomplished by use of toenails or nails subject to withdrawal.
Outdoor stair tread code
Outdoor stair treads must comply with all the general stair tread requirements found in IRC section R311.7.5.2 Treads. The tread depth shall not be less than 10 inches.
Additionally, under section R311.7.5.4 plastic composite exterior stair treads shall comply with the provisions of this section and Section R507.2.2, which states that plastic composite exterior deck boards, stair treads, guards, and handrails shall comply with the requirements of ASTM D7032 and this section.
Outdoor stair nosing code
Outdoor stair nosings must comply with section R311.7.5 Nosings.
Nosings at treads, landings, and floors of stairways shall have a radius of curvature at the nosing not greater than 9/16 inch or a bevel greater than 1/2 inch. A nosing projection not less than 3/4 inch and not more than 1 1/4 inches shall be provided on stairways.
Outdoor stair handrail code
Outdoor stair handrails must comply with all the general IRC handrail requirements found in section R311.7.8 Handrails. Handrail height shall not be less than 34 inches and not more than 38 inches. Handrails must meet the required grip size per section R311.7.8.5. Handrails with circular cross section shall be between 1 1/4 and 2 inch diameter.
Section R311.7.8.6 states that plastic composite handrails shall comply with the requirements of section R507.2.2, which requires that plastic composite handrails comply the requirements of ASTM D7032.
Outdoor stair landing code
Outdoor landings must comply with the requirements of section R311.7.6 Landings for stairways. There shall be a floor or landing at the top and bottom of each stairway and the width perpendicular to the direction of travel shall not be less than the flight served.
Exterior composite decking used for stair landings must comply with the provisions of section R507.2.2.
Outdoor stair railing code
Outdoor stair guardrails must comply with all the general requirements of IRC Section R312.1 Guards.
Exterior plastic composite guards shall comply with the requirements of Section R317.4, which refers to section R507.2.2. Per section R507.2.2 exterior plastic composite guards must be in accordance with ASTM D7032.
Outdoor stair width code
As a means of egress, outdoor stairs must meet all the requirements set forth in IRC section R311.7.1 Width.
Stairways shall not be less than 36 inches in clear width at all points above the permitted handrail heights and below the required headroom height.
Outdoor stair riser code
Outdoor stair risers must comply with IRC section R311.7.5 stair treads and risers. The riser height shall not be more than 7 3/4 inches.
A note on ADA exterior stair requirements
The ADA accessibility standards and IBC accessible means of egress requirements apply to both exterior and interior stairs that are part of a required means of egress. This includes exterior stairs that are part of exit discharge (i.e., the path from an exit to a public way such as a street or alley). IBC Section 1009, accessible means of egress requirements, allows an exterior exit stairway serving levels other than the level of exit discharge to be part of an accessible means of egress.
Final points
Exterior stairs have special requirements for construction and design. The IBC, IRC and ADA building code requirements help to ensure that outdoor stairs are designed, used and constructed in a safe and proper way.
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and the winner of the ugly step award goes to…
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