The overriding principle is that the new stair should be no worse than the original stair when it comes to compliance with the Building Regulations. However, it would be good practice to comply with the Building Regulations wherever possible. The guidance given in Approved Document K 2013 is intended to make a stair safe to use and so one which does not follow this guidance may not be safe.
The requirements of the Building Regulations are:
K1 – Stairs, ladders and ramps
• Stairs ladders and ramps shall be so designed constructed and installed as to be safe for people moving between different levels in or about a building.
K2 – Protection from falling
• any stairs, ramps, floors and balconies and any roof to which people have access, and any light well basement area or similar sunken area connected to a building shall be provided with barriers where it is necessary to protect people in or about the building from falling.
Approved Document K 2013 gives guidance for complying with these requirements.
The guidance below will cover the requirements for private stairs, stairs that serve only one dwelling.
For compliance with requirement K1
Each flight in a single stair should have the same rise and going which should be as follows:
• Any rise between 150 and 220 used with any going between 220 and 300, however the pitch (steepness) must not be more than 42⁰.
Someone using the stair should be able to step comfortably and naturally without having to concentrate too much on where they place their feet. This is achieved when the following relationship is applied:
Twice the rise plus the going (2R+G) should be between 550mm and 700mm
Stairs should have level treads and they can have open risers but treads should then overlap at least 16mm and the opening between the treads should not permit a 100mm sphere to pass through. This is to prevent children becoming stuck or falling through the gap.
The headroom measured from the pitch line of the stair (i.e. from the line of the nosings) should be 2m throughout the stair. However, for a loft conversion, the headroom may be 1.9m in the centre of the stair reducing to 1.8m on the side.
No recommendations are given for the width of a stair, but consideration should be given to the use of a stair (and in other situations fire escape and access need to be considered).
There are no limitations on the length of a private stair but if there are more than 36 rises the stair will need to make a turn of at least 30°.
A landing area should be provided at the top and bottom of each stair and this needs to be a level square whose sides are the same as the narrowest width on the stair. Landings should be clear of permanent obstructions.
However, doors can open onto the landing at the bottom of a flight but must leave an unobstructed area at least 400mm deep across the full width of the landing. Cupboard doors may open in a similar way at the top of a flight but not access doors.
Where a stair consists of straight and tapered treads the going of the tapered treads should be consistent between consecutive treads and not be less than the going of the straight treads. The going of a tapered tread should be measured in the middle of a stair if the width is less than 1m otherwise the going is measured 270mm from each side. The going at the narrow end of a tapered tread should be at least 50mm.
A stair should have a handrail on one side if it is up to 1m wide and wider stairs should have a handrail on both sides. However, a handrail is not required beside the two bottom steps of a private stair. The top of the handrail should be between 900mm and 1000mm from the pitch line.
For compliance with requirement K2
Private stairs should be guarded at the sides where the drop is more than 600mm. The design of the guarding should prevent a 100mm sphere to pass through and should not be readily climbable by children. The guarding should be 900mm above the pitch line on a flight and 900mm above the floor on a landing.
For further guidance, please contact Kevin Underwood, BWF Technical Manager, on 0844 209 2614. Our latest BWF Stair Scheme Fact Card (PDF) is available and you can now Download the Stair Installation Guide: Top 10 Tips (PDF)
We are also delighted to announce the launch BWF Stair Scheme Design Guide at the next Stair Scheme Seminar: Timber Stairs: Fundamental designs, fabulous results on 22nd October. You can also view the previous BWF Stair Seminar Presentation that took place in March 2012 (PDF; 7.2MB)
The BWF Stair Scheme is focussed on promoting effective design, reliable manufacture, developing guidance where standards and regulations are in conflict, and ensuring best practice advice is passed to installers to reassure that products made by BWF accredited stair manufacturers consistently meet the relevant performance requirements.