Kevin Underwood at the British Woodworking Federation (BWF) looks at how to balance the important twin drivers of aesthetics and safety in staircase design
It’s no surprise that aesthetic considerations are often the key driver behind staircase selection. The BWF’s 2021 Home Improvement Index showed that safety lagged behind design and budget considerations when it came to a choice of staircase.
However, stairs can be a common site for accidents and a critical area of non-compliance with Building Regulations. Poorly designed staircases can result in serious injury – and even death – from slips, trips and falls, making safety a paramount consideration in staircase design. The following paragraphs contain the key factors for safe specification.
The role of handrails
Handrails’ primary functional role should be to offer safety support, particularly when a user slips or trips. If you’re unsure whether a handrail is needed, a useful guide is that stairs with a rise of over 600 mm should have one and, where the stair width is more than 1,000 mm, a rail should be fitted on both sides.
When approaching handrail design, be sure to think about practical considerations. For instance, a rail should naturally be within easy reach at all points of a staircase and should contrast with the background, for accessibility to a wide range of users, without being too highly reflective. The surface should be slip resistant and not be too hot or cold to touch, while the ends of the handrail should be finished so as to reduce the risk of clothing being caught.
It is of course important to think about the finish of the stairs. Wet or dusty surfaces, worn or thin carpets and various types of hard flooring can all increase risk, so when designing the staircase, the slip resistance of the material should be considered.
Where the ‘going’ of the stair (i.e. the distance between individual risers) is 300 mm or more, users tend to be less affected by the slipperiness of the surface, but on stairs with smaller treads, thought should be given to a degree of slip resistance at the nosing, as this is where first contact is made in descent.
Nosings, risers & goings
When it comes to nosings, a staircase user must be able to identify where they are for each step. Sometimes a patterned carpet, tiles or timber finish can make this difficult, so consider applying contrasting material to the nosings. It’s also worth noting that nosings should not reach too far over the step below as this could create a trip hazard.
One of the biggest influences on staircase safety is the design of rises and goings. The relationship between the two should allow the user a natural stride without the feeling of having to over-reach or take unnecessarily small steps. Keeping the going over 250 mm should ensure that the user can place most, if not all, of their foot on the tread.
Any variations in the rise and going can lead to a person tripping or stumbling as they go, so stairs must be as consistent as possible.
Open risers are acceptable for private stairs, but should be avoided in public buildings. Having an open riser increases the likelihood that a person’s foot can get caught below the nosing, potentially causing them to trip. Also, an open riser which allows the user to look through a staircase, can lead to disorientation and loss of balance.
Staircases higher than 600 mm – or where there are two or more risers – should incorporate some form of barrier or guarding to prevent the risk of a user falling over the side. Whether this is a screen or balustrade, it must be high enough to prevent anyone falling over it and strong enough to withstand someone falling into it.
Gaps should be less than 100 mm in any building where the stairs are normally used by children under five, as they could be at risk of becoming trapped or falling through.
The right space
When it comes to the space around a staircase, there needs to be at least 2 metres of headroom above the stairs and landings. When designing the staircase’s width, it’s important to bear in mind the number of people likely to be using it at once as a means of escape in a fire. At a minimum, stairs in public buildings should not be less than 1,200 mm wide. There should be a landing area at the top and bottom of each flight of stairs that’s at least as long as the width of the stair.
Starting the staircase design process with these key principles in mind will ensure that the aesthetic elements will enhance a building’s interior environment without compromising on the safety.
While Building Regulations are useful in providing information on producing stairs with an acceptable level of safety, the Code of practice BS 5395-1 offers the most comprehensive set of guidelines.
In addition, a useful safety resource available to assist professionals who are responsible for the design of staircases is the British Woodworking Federation’s Stair Scheme, which has published a number of best practice guides and factsheets.
Kevin Underwood is technical director at the British Woodworking Federation (BWF)