Typical Platform Stair Width

Minimum Widths

• The minimum width for stairs in many cities and states is 3 feet. As a result, most stair landings are 3 feet wide. The length of stair landings also is typically 3 feet, which makes landings take on a square shape. Also, any outdoor stairway must have a landing at least 3 feet wide and 3 feet long. The minimum width of stairs applies to L-stairs and U-stairs. The U.S. Department of Housing and Urban Development (HUD) established the minimum dimension required for stairs and stair platforms.

L-Stairs

• L-stairs have a 90-degree turn at some point in the staircase. The stair platform for L-stairs is found near the top, bottom or the middle of the stairs. A “Long-L” staircase is a staircase with a landing near the staircase's top or base. Another term for a stair platform on L-stairs is a quarter landing. Double L-stairs features two 90-degree turns at the platform instead of one turn. L-stairs are safer and easier to climb than straight stairs, according to home building expert Don Vandervort.

U-Stairs

• U-stairs divide stair runs with a 180-degree turn at the stair's platform. The typical width of a U-stairs platform is approximately 6 feet, since the platform must be wide enough to service two stair flights. Both flights of stairs are typically 3 feet wide. U-stair platforms are also known as half landings. The U-stairs platform width changes depending on whether the staircase is a wide U or narrow U. The difference between wide U-stairs and narrow U-stairs is the space between both flights of stairs. U-stairs are also known as return stairs.

Outdoor Landings

• Some outdoor straight-run stairs have landings at the top of their staircases. A straight-run staircase is a flight of steps with no turns. Outdoor stair platforms are typically found on stairs leading up to a house's entrance. The 3-by-3-foot minimum dimension requirements set by HUD applies to outdoor staircases as well. However, stairs and stair platforms may be wider for outdoor steps since outdoor space is not as restricted as indoor space.