Regulations for the design and construction of stairs are set out in Part K of the building regulations, and compliant designs are described in Approved Document K - Protection from falling, collision and impact.
The treads of stairs are the horizontal parts which people step on.
The leading edge of the tread is described as the ‘nosing’. In buildings other than dwellings, the nosing should be visually contrasting, and a suitable tread nosing profile, should be used. See nosing for more information.
Steps should have level treads with the rise and going of each step consistent throughout a flight of steps and are in accordance with the table below.
In buildings other than dwellings, risers should not be open to avoid feet or walking aids being caught underneath the tread during ascent, possibly causing a fall or giving occupants a feeling of insecurity. For dwellings, steps may have open risers if treads overlap by a minimum of 16mm and steps are constructed so that a 100mm diameter sphere cannot pass through the open risers.
A tapered tread is a step in which the going reduces from one side to the other. Where stairs have tapered treads, consecutive treads should use the same going. If a stair consists of straight and tapered treads, the going of the tapered treads should not be less than the going of the straight treads.
Alternating tread stairs are stairs with paddle-shaped treads where the wide portion is on alternate sides on consecutive treads. In dwellings, alternating tread stairs may only be used in loft conversions where there is not enough space for conventional stairs and where the stair is for access to only one habitable room and, if desired, a bathroom and/or a WC (although this must not be the only WC in the dwelling).
Alternating tread stairs should; make alternating steps uniform with parallel nosings, have slip-resistant surfaces on treads, have tread sizes over the wider part of the step in line with the table above, should provide a minimum clear headroom of 2 m, should be constructed so that a 100 mm diameter sphere cannot pass through the open risers and should comply with the diagram below.
 Related articles on Designing Buildings Wiki
Featured articles and news
This article explains the Buildings Regulations completion certificate, what it is, and when its needed.
Graphene has many potential applications, but when will it start being used in civil engineering?
Increasing productivity – now more than ever as we lead up to Brexit – should be the sector’s number one priority in 2018.
Carillion's collapse causes Construction Leadership Council to delay the construction sector deal report.
Urban Heritage, Development and Sustainability: international frameworks, national and local guidance.
What will the General Data Protection Regulations (GDPR) mean for you when they come into force in May?
Business Secretary chairs a new taskforce to monitor and advise on mitigating the impacts of Carillion’s liquidation.
Sir John Armitt is appointed the new chair of the National Infrastructure Commission.
High quality and high density homes - is it what we need or is it storing up trouble?
Government announces its intention to strengthen planning rules to protect music venues and neighbours.
National Audit Office reports that there is little evidence that PFI offers better value than other forms of contracting.
What is liquidation and how does it apply to contractors in the construction industry?