Complete Stair Building GuideUK Building Regs, Calculations & Materials

Stair Anatomy

Before building, understand the key components and terminology.

• •Rise (Riser): Vertical distance between treads. Private max 220 mm. All within 5 mm.
• •Going (Tread): Horizontal distance nosing to nosing. Private min 220 mm.
• •Stringer (Carriage): Diagonal structural member. 50×300 mm for cut stringers.
• •Tread: Horizontal stepping surface. 36–40 mm hardwood. 20–30 mm nosing.
• •Riser: Vertical board between treads. 18–20 mm.
• •Nosing: Front edge overhang. 16–25 mm.
• •Handrail: Required on one side for flights over 600 mm. Height 900–1,000 mm.
• •Baluster (Spindle): Vertical members. Max 100 mm gap.

Understanding these components is essential for Building Regs compliance.

UK Building Regulations (Approved Document K)

Approved Document K sets the standards for stairs in England and Wales. Scotland and Northern Ireland have equivalent regulations.

• •Rise: Max 220 mm (private), 190 mm (common/utility). All within 5 mm.
• •Going: Min 220 mm (private), 250 mm (common/utility).
• •Width: Min 800 mm private, 900 mm common.
• •Headroom: Min 2,000 mm.
• •Handrail: Required on one side for flights over 600 mm rise. 900–1,000 mm high.
• •Landings: At top and bottom. Min width of stair, 800 mm deep.
• •Guarding: Required when drop exceeds 600 mm. Min 900 mm high.
• •Lighting: At top, bottom, and landings.

These are minimums for Approved Document K. Always check with Building Control. A Building Notice or Full Plans application may be required.

How to Calculate Stairs

Calculating stairs involves determining step count, rise, going, and stringer length.

1. Step 1 — Measure total rise between finished floor levels.
2. Step 2 — Divide by 190 mm = number of risers. E.g., 2,700 / 190 ≈ 14.
3. Step 3 — Actual rise = 2,700 / 14 = 192.9 mm. Check ≤ 220 mm.
4. Step 4 — Going: min 220 mm. 2R + G = 550–700 mm. With 193 mm rise, going of 264 mm = 650.
5. Step 5 — Number of goings = risers - 1 = 13.
6. Step 6 — Total going = 13 × 264 = 3,432 mm.
7. Step 7 — Stringer = √(2,700² + 3,432²) = 4,367 mm.
8. Step 8 — Check 2,000 mm headroom at every point.

Use our free Stair Calculator for instant results.

Common Stair Types

The type depends on space, budget, Building Regs, and aesthetics.

• •Straight Stairs: Simplest. One flight. 3–4.5 m run. Most economical.
• •Quarter-Turn (L-Shaped): 90° turn at landing. Reduces linear footprint.
• •Half-Turn (U-Shaped): 180° turn with landing. Less length, more width.
• •Spiral Stairs: Compact around centre column. From 1,200 mm diameter. Secondary access.

Straight when space permits. L or U for limited space. Spiral for secondary access.

Materials & Costs

Material choice affects cost, durability, appearance, and maintenance.

Cost Breakdown

Costs vary by design complexity, materials, and DIY vs professional.

Frequently Asked Questions