L-Shaped & U-Shaped Stair Stringers Design Guide
How to break long stair flights with intermediate landings, compute turn stringers, and adhere to maximum 151-inch vertical rise limits.
M
Mark Henderson, Master Carpenter
Carpentry & Construction Author
Building codes require an intermediate landing for any stair flight exceeding 12 feet (144–151 inches) of vertical rise.
Intermediate landings allow stairs to turn 90 degrees (L-shape) or 180 degrees (switchback/U-shape), reducing horizontal space demands while dramatically improving pedestrian safety.
Ready to Calculate Your Stairs?
Use our free online stringer calculator to get exact rise, run, throat depth, and board sizing.
Launch Stringer Calculator →
