Stairway and Exterior-Door Landing Check
Whether a stair's top and bottom landings meet code.
Example
You enter
- Landing depth in the direction of travel (in) 36
- Landing width (in) 36
- Width of the flight or door served (in) 36
- Landing below the threshold (in; doors only) 1.5
- Landing serves door
- Minimum landing depth (in; IRC 36) 36
- Maximum threshold drop (in; IRC 1.5) 1.5
You get
- Depth in the direction of travel OK
- Width against the served opening OK
- Threshold drop OK
- Min landing area (ft²) 9
- Provided area (ft²) 9
Checked against published worked examples from: International Code Council.
Details, formula, and sources
ScopeIRC R318.7.6 [R311.7.6 in IRC 2021] wants a landing at the TOP AND BOTTOM of every flight, at least as WIDE as the flight and, on a straight run, 36 in deep in the direction of travel. IRC R318.3 [R311.3 in IRC 2021] wants 36 in at an exterior door too, plus the rule that catches people: the floor at a required exit door not more than 1.5 in below the top of the threshold -- a landing set a full step down is a fall, not a step. The trap this makes visible is that AREA does not settle it: a 30 x 48 in landing has 10 sq ft against a 9 sq ft minimum and still FAILS, because the 36 in is measured along the path you actually walk, not across the landing. Both minimums are editable; IBC and accessible routes want more.
Formula or tabledepth ok when landing depth in the direction of travel >= 36 in; width ok when landing width >= the width of the flight or door served; at a door, threshold ok when the landing is not more than 1.5 in below the top of the threshold; smallest compliant landing = minimum depth x served width.
Source and editionIRC R318.7.6 [R311.7.6 in IRC 2021] (a floor or landing at the top and bottom of each stairway, width perpendicular to the direction of travel not less than the width of the flight served, and on a straight run a depth in the direction of travel not less than 36 in) and IRC R318.3 [R311.3 in IRC 2021] (landings at exterior doors not less than 36 in measured in the direction of travel, with the floor or landing at the required exit door not more than 1.5 in lower than the top of the threshold).
Free accessBoth are short prescriptive provisions reproduced in state adoptions, building-department stair handouts, and code-viewer sites. No table is reproduced and both minimums are editable inputs.
What governsEstimate. AHJ and licensed professional govern.
API field nameslanding_depth_in, landing_width_in, flight_width_in, threshold_drop_in, kind, min_depth_in, max_threshold_drop_in, depth_deficit_in, width_deficit_in, drop_excess_in, min_landing_area_sf, provided_area_sf
- Stairway landing top and bottom of each flight; width >= flight width; straight-run depth >= 36 inIRC R318.7.6 [R311.7.6 in IRC 2021]
- Door landing >= 36 in in the direction of travelIRC R318.3 [R311.3 in IRC 2021]
- Threshold drop not more than 1.5 in below the top of the threshold at a required exit doorIRC R318.3 [R311.3 in IRC 2021]
- Depth is directional measured along the path of travel; area does not substitute for itcode wording
- Straight run only a turning landing has its own geometrystated scope limit
- Not checked whether a landing is required, exceptions, guards, headroom, slope, framingstated scope limit