Staircase Design Requirements

What This Requirement Covers

Approved Document K sets out the requirements for staircases, ramps, and guarding to protect people from falling. These requirements cover the design of new staircases in dwellings and non-domestic buildings, as well as alterations to existing staircases.

Key Requirements

Domestic Staircases

1. Rise (riser height): Maximum 220 mm per step
2. Going (tread depth): Minimum 220 mm per step
3. Pitch: Maximum 42 degrees
4. The relationship between rise (R) and going (G) must satisfy: 2R + G = 550 to 700 mm
5. Stair width: Minimum 600 mm between walls (or between a wall and the balustrade); common standard is 800-900 mm
6. Headroom: Minimum 2.0 metres measured vertically above the pitch line
7. Landing: A landing at least the width of the stair must be provided at the top and bottom of each flight
8. Maximum number of risers in a flight: 36 (but a landing is recommended every 16 risers)

Non-Domestic Staircases

1. Rise: Maximum 170 mm per step
2. Going: Minimum 250 mm per step
3. Stair width: Minimum 1200 mm for stairs serving more than 50 persons
4. Headroom: Minimum 2.0 metres
5. The going of each step must be uniform throughout the flight

Handrails

1. A handrail must be provided on at least one side of all staircases
2. In non-domestic buildings and in dwellings where the stair width exceeds 1000 mm, handrails are required on both sides
3. Handrail height: 900-1000 mm above the pitch line of the stair and above the landing
4. The handrail must be continuous along the full length of the flight (including landings)
5. Handrails must be graspable: circular section 40-50 mm diameter, or oval/rectangular with equivalent grip

Guarding (Balustrades)

1. Guarding is required where there is a drop of more than 600 mm (dwellings) or 380 mm (non-domestic buildings, or where children under 5 may be present)
2. Minimum guarding height: 900 mm for stairs, 1100 mm for landings, balconies, and floor edges
3. Guarding must not be climbable by children: no horizontal rails, footholds, or gaps that a 100 mm sphere can pass through
4. In locations where children under 5 are likely to be present, the gap between balusters must not exceed 100 mm

Loft Conversion Stairs

1. Where space is limited, Approved Document K permits alternating tread stairs (paddle stairs) for loft conversions serving a single habitable room
2. Alternating tread stairs have a minimum going of 220 mm on the wider part of each tread
3. A conventional stair is always preferred where space allows

Practical Compliance Tips

1. Calculate the rise and going at the design stage to ensure the staircase fits within the available space while meeting the dimensional requirements
2. Ensure uniform rise and going throughout each flight; variations cause trips
3. Allow for the finished floor thickness when calculating the total rise; this is commonly overlooked, resulting in a final riser that is a different height
4. Staircase headroom is measured vertically from the pitch line to the soffit above; check this at the nosing of each step, not just at the top and bottom
5. Specify balustrade details that prevent climbing; horizontal bar designs are attractive but may not comply if children under 5 are present
6. In loft conversions, plan the staircase position carefully; it affects the usable floor area in both the loft and the floor below
7. Building Control will inspect the staircase at the relevant stage; have the handrails, guarding, and nosings installed before requesting inspection