Understanding Stair Design
Proper stair design is crucial for safety and comfort.
- Rise and Run The rise-to-run ratio determines comfort and safety.
- Headroom Minimum 6'8" clearance required above all treads.
- Width Minimum 36" for residential, wider for commercial.
- Handrails Required on at least one side, specific height requirements.
Code Requirements
Riser Height
Maximum 7.75", minimum 4". Must be uniform within 3/8".
Tread Depth
Minimum 10" measured nose to nose. Uniform within 3/8".
Nosing
Required when tread depth < 11". Maximum 1.25" projection.
Landing Size
Minimum width of stair, minimum 36" in direction of travel.
Construction Methods
- Wood Frame Common in residential. Uses stringers cut from dimensional lumber.
- Concrete Durable, fire-resistant. Common in commercial buildings.
- Steel Strong, versatile. Can achieve longer spans.
- Composite Modern materials. Combines strength with lower maintenance.
Safety Features
Non-Slip Surface
Use proper materials or treatments. Critical for safety.
Lighting
Adequate illumination required. Consider night lighting.
Visibility
High contrast nosing. Clear visual definition of steps.
Guards
Required for drops > 30". Specific height and spacing requirements.
Advanced Design
- Winders Special requirements for turning stairs. Minimum tread width at walk line.
- Spiral Stairs Limited use in egress. Special code requirements.
- Curved Stairs Complex geometry. Requires careful planning.
- Floating Stairs Special structural requirements. Modern aesthetic.