Landing Framing 101

IRC R311.7.6 sets two non-negotiable minimums for any stair landing: the width perpendicular to travel must be at least as wide as the stair it serves, and where the run is a straight flight, the depth in the direction of travel must be at least 36 in / 914 mm. A 36 in wide stair therefore needs a landing that’s a minimum of 36 in square — and landing framing is what actually holds that platform up, structurally, it’s built exactly like a small deck: joists, a beam, posts, and a footing.

How a Landing Is Actually Framed

A landing carries the same live-load basis as the rest of the stair: 40 psf uniform plus a 300 lb concentrated load check per IRC Table R301.5, applied because the landing functions as a walking surface exactly like a tread does. That load gets picked up by joists spanning between a ledger (or beam) on one side and a beam on the other, with the beam typically carried on posts down to footings, unless the landing is small enough to cantilever or is directly supported by a masonry wall.

Worked example: a 42 in / 1067 mm wide stair terminating at a landing that’s 42 in wide by 48 in / 1219 mm deep — deeper than the 36 in code minimum to give a comfortable turn radius. That landing needs joists spanning the 42 in width, typically doubled or tripled where the stringers attach, carried by a beam sized for the landing’s tributary load using the same beam-span method used for the rest of the stair frame. Enter your landing’s actual dimensions into the Landing Framing Calculator to get joist size, spacing, and beam requirements for that specific footprint.

Why Landing Dimensions and Framing Are Linked

The code-minimum dimensions in R311.7.6 exist for a reason that directly affects framing: a landing narrower than the stair it serves creates a pinch point exactly where someone is transitioning from a sloped surface to a flat one, and a landing shallower than 36 in doesn’t give a full stride of flat surface before the next flight starts. Framing has to accommodate whatever dimension the code requires, not the other way around — undersizing the platform to simplify the framing is not a legitimate shortcut.

Many jurisdictions also require an intermediate landing partway up any run where the total vertical rise exceeds roughly 12 ft / 3.7 m — this is a common state and local amendment rather than a universal IRC baseline, so it’s worth confirming the exact trigger height with the local building department before finalizing a tall exterior stair design. Where it applies, that mid-run landing gets framed identically to a top or bottom landing: joists, beam, posts, footings, sized for the same load table.

Common Mistakes

Undersizing the landing footprint. A landing gets built to whatever scrap decking or leftover joist length is on hand rather than to the code-minimum width-of-the-stair and 36 in depth rule. An inspector will flag this at final, and retrofitting a landing after the stringers and railings are already installed is far more disruptive than sizing it correctly the first time.

Leaving one edge of the landing unsupported. The ledger-side edge gets properly attached, but the outer edge is left resting on fill dirt or an unrated paver instead of a beam on footings. The landing then settles unevenly, which shows up as a landing that’s no longer level with the top of the stringers it’s supposed to meet flush.

Weak ledger connection at the house side. A landing ledger gets nailed to rim joist or siding the same way a deck ledger sometimes is, without through-bolting or lag-screwing into solid framing per a rated connection table. This is the same failure mode responsible for most deck-ledger collapses, and a landing ledger carries an added concentrated tread load on top of the standard uniform load a deck ledger sees. Size the connection with the Ledger Board Attachment Calculator, not a generic nailing schedule.

Mismatched landing height at the top riser. The landing gets framed slightly high or low relative to the last stringer cut, creating a top or bottom riser that’s noticeably taller or shorter than the rest — a trip hazard and, past a small tolerance, a code violation on riser uniformity. Confirm the finished landing surface height against the stringer layout before the stringers are permanently fastened, not after.

Related Calculators You Might Need

Landing framing depends directly on the beam that carries it — use the Stair Beam Span Calculator to size that member for the landing’s specific tributary load. Whatever the beam rests on needs a footing sized for local frost depth and the tributary load, using the Stair Footing Size Calculator. The joist-to-beam and joist-to-ledger connections typically need rated hangers — the Joist Hanger Count Calculator works out an accurate hardware count from your joist layout. Before finalizing dimensions, confirm the platform meets the minimum footprint with the Landing Size Calculator, and run the full assembly through the IRC Stair Code Checker to catch anything the framing alone won’t flag.

Frequently Asked Questions

How big does a stair landing need to be? At minimum, as wide as the stair it serves and at least 36 in / 914 mm deep in the direction of travel for a straight-run stair, per IRC R311.7.6. Landings of other shapes need a depth and area at least equal to a quarter circle with a radius equal to the required width. Check your specific footprint against the Landing Size Calculator before framing.

Do I need a landing on outdoor stairs? Yes — the landing requirement in R311.7.6 applies at both the top and bottom of any stairway, interior or exterior, with a narrow exception for the top of certain interior flights where no door swings over the stairs. Exterior stairs at a deck, porch, or entry door need a code-compliant landing at both ends just like an interior stair does.

Can a landing be smaller than the width of the stair? No. R311.7.6 explicitly ties landing width to the width of the flight it serves — the landing can’t be narrower than the stair. It can be wider, and often is, to accommodate a door swing or a turn in the stair layout, but never narrower.

Does a stair landing need its own footing? If the landing is elevated above grade — at a deck, porch, or second-story exterior stair — yes, it needs the same kind of footing support as the beam and posts holding up any other elevated structure. A landing directly poured as part of a concrete slab at grade doesn’t need a separate footing in the same sense, since the slab itself bears the load.