| Stringers | 2″ x 12″ (typically 10-14 ft length) | 2-3 per staircase | Stringers support the treads and risers. Typically, 2 are used for narrow stairs, 3 for wider stairs (more than 36 inches). |
| Treads | 2″ x 10″ or 2″ x 12″ (cut to width of stair) | 1 per step | The flat part of each step. Choose durable wood (e.g., pressure-treated pine) for exterior stairs. |
| Risers | 1″ x 8″ or 1″ x 10″ (cut to width of stair) | 1 per step (minus 1 for top step) | The vertical piece between each tread. Omit if open risers are desired. |
| Landing (if needed) | Plywood sheets (3/4″ thick) | 1-2 sheets (4×8 ft) | Used for intermediate landings in longer staircases or exterior decks. |
| Posts | 4″ x 4″ (typically 4-8 ft height) | 1 at each end and turn point of handrail | Provides support for the handrails and is required for safety on open staircases. |
| Handrails | 2″ x 4″ or 2″ x 6″ (length of staircase) | Varies by stair length | Installed along open sides or walls. One handrail is typically required for narrow stairs, two for wider. |
| Balusters | 2″ x 2″ or custom spindle (height varies) | 1 per 4-5 inches of stair width | Vertical supports for handrails, required to meet safety standards. Baluster spacing typically does not exceed 4-5 inches. |
| Hardware | Nails, screws, brackets, wood glue | Based on stair length and type | Connects stringers, treads, and risers securely. Use weather-resistant hardware for exterior stairs. |
| Finishing Lumber (Optional) | 1″ x 2″ or 1″ x 3″ trim boards | Based on stair length and riser width | For added visual appeal on stair sides, risers, or handrails. Optional but enhances the look. |
| Stair Width | 36-48 inches | Determines required materials | Standard width for residential stairs is 36 inches; wider stairs require more lumber. |