A staircase that feels springy underfoot creates user insecurity and leads to premature fastener loosening. Proper stringer spacing ensures structural rigidity.
Wood vs. Composite Tread Spanning
- Dimensional 2×6 or 2×12 Wood Treads: Can span up to 16 inches on center (O.C.) for standard residential live loads.
- Capped Composite Decking (PVC / Composite): Most manufacturers (Trex, TimberTech, Deckorators) require maximum 12-inch or even 9-inch O.C. stringer spacing for stair treads.
Number of Stringers = Math.ceil(Stair Width / Max Allowed Spacing) + 1