6.6 Staircases
SCOPE
DESIGN STANDARDS
Design that follows the guidance below will be acceptable for staircases.
STATUTORY REQUIREMENTS
Design should be in accordance with relevant Building Regulations and other statutory requirements.
SAFE TRANSMISSION OF LOADS
Generally, all stairs and staircases should comply with BS 5395 : Parts 1 and 2.
Items to be taken into account include:
Timber domestic staircases with straight flights and quarter- or half-landings should comply with BS 585. Particular attention should be paid to the performance requirements for strength, deflection and vibration under load, given in BS 585 : Part 2.
The method of fixing flights to the surrounding structure should be specified.
Reinforced concrete staircases should be designed to BS 8110 and comply with Chapter 2.1 'Concrete and its reinforcement' (each section) and, where appropriate, designed by an Engineer in accordance with Technical Requirement R5.
Steel staircases should be designed to BS 5950.
Proprietary staircases should:
- comply with an assessment in accordance with Technical Requirement R3
- be suitable for their required use and location.
When considering differential movement in relation to setting out, levels and finishes, allowances should be made for:
- casting tolerances
- deflection under load
- foundation settlement
- creep and shrinkage
- storey height.
STAIRCASE WIDTH AND HEADROOM
(a) headroom
The minimum headroom above stairs should be measured vertically from the pitch line. The clear headroom (h) over the entire length and width of a stairway, including landings, should be 2.0m.
(b) minimum unobstructed width
No recommendations are given for minimum widths in England, Wales and the Isle of Man. Where staircases form part of means of escape, reference should be made to the relevant Building Regulations.
Dimensions for stair widths in Scotland and Northern Ireland should be in accordance with relevant Statutory Requirements.
DESIGN OF STEPS
Items to be taken into account include:
(a) pitch
The maximum angle of pitch of a stairway should not exceed:
- 42° for private stairs
- 38° for common or access stairs.
The dimensions for maximum rise and minimum going should be:
Type of stairs | Maximum rise [mm] | Minimum going [mm] |
Private stairs | 220 | 220 |
Common stairs (not Scotland) | 190 | 250 |
Access stairs (Scotland) | 190 | 250 |
The dimensions of the rise (R) and the going (G) should usually be related so that 2R+G is between 550mm and 700mm.
A design aid giving the relationship between rise and going is given in Appendix 6.6-A.
Further information on staircase design may be found in BS 5395.
(b) consistent rise and going
In each flight of stairs all the steps should have the same rise and going.
The thicknesses of screeds and floor finishes should be taken into account.
(c) tapered treads and winders
The rise of tapered treads should be the same as that of adjacent parallel treads. The going should be uniform and not less than the going of the associated straight flight. The going should be measured from the centre line of the straight flight (as shown below).
Minimum going (g) [mm] | |
England and Wales | 50 |
Scotland | 50 |
Northern Ireland | 50 |
Isle of Man | 50 |
(d) safe foothold
All steps should have level treads.
Stairs with open risers should have treads that overlap 16mm minimum.
Where stairs are open to the weather or may otherwise become wet, a non-slip finish or an insert to each tread should be specified.
LANDINGS
Landings should be provided at the top and bottom of every flight. The width and depth of landings should be at least the same as the width of the stair.
Landings should be properly framed to provide full support and secure fixings for flights, nosings, newels, etc.
Where pivot windows are being used, they should not obstruct the landing area or stair flight when in the open position.
Generally, door swings should not obstruct landings. However, a door may open across the bottom landing of a flight of private stairs if the swing is at least 400mm from the first tread and the dwelling is not over two storeys high.
HANDRAILS
A handrail is required to all flights of stairs that rise over 600mm.
Where winders are used, Building Regulations (Northern Ireland) require a handrail to be fitted on the side where tapered treads have the greater going.
Handrails should be at a height between 900mm (840mm in Scotland) and 1000mm.
Design should ensure:
- a firm handhold
- that trapping or injuring the hand is prevented
- a minimum 25mm clearance at the back of the handrail
- secure fixing
- that handrail ends do not project to catch clothing, etc.
GUARDING
Items to be taken into account include:
(a) resistance to loads
Guarding should be:
- capable of resisting a horizontal force of 0.36kN/m at its minimum required height
- a solid wall or balustrading.
Where guardrails or balustrades are long, the newel posts may not be sufficient to transfer horizontal forces to the structure and intermediate posts may be needed.
The method of fixing newels should be specified (eg through-bolted to joists).
Any glazing in the guarding should be toughened or laminated glass, or glass blocks. Wired glass is not regarded as safe for this purpose and should not be used.
(b) dimensional requirements
Guarding should be provided along the full length of the open sides of all stairs and landings when the drop is more than 600mm at any point. To comply with relevant Building Regulations, guarding may be required where a stair abuts an opening window.
Guarding is not needed when the rise is less than 600mm and when the stair or landing is not a means of escape.
Balustrading should be designed so that it is not easily climbed by children.
No opening in the balustrade should be large enough for a 100mm diameter sphere to pass through.
Type of stairs | Minimum guarding height [mm] | |
flights | landings | |
Private stairs (England, Wales, Northern Ireland and the Isle of Man) |
900 | 900 |
Private stairs (Scotland) | 840 | 900 |
Common stairs | 900 | 1100 |
FIRE PRECAUTIONS
Timber staircases are acceptable within a single family dwelling where there are no more than four storeys, excluding the basement.
Houses of three or more storeys and flats in buildings of three or more storeys should comply with the relevant Building Regulations.
Ventilation of staircases serving flats in buildings of three or more storeys should comply with BS 5588.
LIGHTING
Artificial light sources should be provided to all staircases and landings. Within dwellings, lighting to stairs should be controlled by two way switching.
Where the Public Lighting Authority specify and maintain control of entrance lighting, their requirements should be met. Otherwise, landings and staircases in common areas to dwellings should be provided with adequate artificial lighting. Manual two way switching, controlled by people using these areas is acceptable. Automatic light sensitive controls may be used, provided lights can also be switched two way manually.
Reference should be made to Chapter 8.1 'Internal services' (Design) for further details on lighting.
Where staircases are lit by glazing, any glass below the minimum height of guarding (see Table to Clause D8(b)) should be:
- protected by a balustrade or railing, or
- glass (toughened or laminated), or
- constructed of glass blocks.
PROVISION OF INFORMATION
Usually, staircase drawings and specifications should show:
- layout of stairs
- dimensions covering width, rise and going, handrail height, etc
- fixings of stairs, treads, risers, strings, balustrades, newel posts and handrails, as appropriate
- the length of time before formwork can be removed from in-situ concrete stairs
- whether precast concrete or steel staircases can be used immediately after erection or whether time should be allowed to cure grouted connections.
Ensure that design and specification information is issued to site supervisors and relevant specialist subcontractors and/or suppliers.