A stair landing is a level platform that interrupts a run of steps. It does three jobs at once: it gives someone a place to stop and recover on a long climb, it provides a safe place to change direction, and it limits how far a person can fall in a single uninterrupted flight. Because of that last point, landings are treated as a safety requirement by every major building code rather than a design nicety, and they are one of the dimensions inspectors check first.
Landings break a long flight into safer segments and provide a place to change direction. Under the US IRC, a single flight may not exceed 147.0 inches of vertical rise without a landing. That figure is not arbitrary — it works out to a flight of roughly 19 risers at the 7.75-inch maximum, which is about as far as a person should fall in one uninterrupted run. The UK and Australia take a different approach, limiting the number of risers per flight — 36 and 18 respectively — rather than the rise height.
The practical takeaway: if your floor-to-floor height pushes a straight run past 147 inches of rise (about 12.25 feet), you must split it with an intermediate landing. Most single-storey residential stairs come in under that limit, so the rule bites hardest on tall commercial flights, split-level homes, and deck stairs descending to a low grade.
A landing must be at least as deep, in the direction of travel, as the stair is wide, and never less than 36 inches under the IRC. The "direction of travel" detail matters: depth is measured along the path you walk, not across the landing. A landing narrower than the stair creates a pinch point and fails inspection.
Worked example: a 42-inch-wide stair needs a landing at least 42 inches deep in the direction of travel, because the stair width (42) exceeds the 36-inch floor. A 32-inch-wide stair — below the residential minimum width anyway — would still need the full 36-inch landing, because the code-mandated floor applies regardless of how narrow the steps are. When a stair changes direction at the landing, the landing must satisfy the depth rule in both travel directions, which is why turn landings are usually square.
Quarter-turn (L-shaped) and half-turn (U-shaped) stairs use a landing to change direction. The landing replaces a tread and consumes floor area, but it is safer and easier to build than winder treads for the same turn. A quarter-turn uses a single landing to make a 90-degree change; a half-turn uses either one larger landing or two quarter-landings to double back 180 degrees, which is the most compact way to climb a full storey within a small footprint.
The trade-off is floor space. A landing-based turn needs a clear square at least as big as the stair width on each side, whereas winder treads turn within the run itself. If floor area is tight, winders save space; if you want the easiest, most code-forgiving build, a landing wins.
Where a door opens onto a stair, codes require enough landing depth that the door swing does not push someone toward the steps. The IRC generally requires a landing at the top and bottom of each stairway, with a specific allowance: a door is permitted to swing over the landing only if the landing is deep enough that the door, at any point in its swing, leaves the required clear depth. Australia, for example, requires a landing of a minimum length where a door opens over a change in level greater than three risers.
A common real-world failure is a back door that opens directly over the top step of a deck stair — the swing sweeps the very edge of the drop. The fix is either a deeper landing or a door that swings away from the stair.
Size an L- or U-shaped stair with its landing in the L-shape and U-shape calculators, and check the minimum platform size in the landing size calculator.
How to Build Deck Stairs (Step by Step) · Stair Codes by Country: A Comparison · Winder Stair Geometry Explained