Double Stringer Stairs -

: Over-cutting stringers (especially with a circular saw) is the #1 cause of stair failure. Finish corners with handsaw.

| Stair width | Stringer configuration | |-------------|------------------------| | ≤ 30″ | Double stringer (2) | | 30–36″ | Double stringer possible, but check deflection | | 36–48″ | Triple stringer (2 outside + 1 center) | | >48″ | 4+ stringers or engineered steel | double stringer stairs

Use 2×12 material at least 18′ long.

√(176.25² + 106²) = √(31064 + 11236) = √42300 ≈ 205.6″ (17′1½″) : Over-cutting stringers (especially with a circular saw)