Kevin Underwood of the British Woodworking Federation outlines the vital importance of good staircase design when it comes to preventing injuries
The risks presented by stairs are self-evident. While a homeowner may believe that this type of accident would not happen to them, the Royal Society for the Prevention of Accidents’ (RoSPA) report ‘Can the home ever be safe’ revealed that there are over 300,000 visits annually to A&E departments following falls on stairs.
These accidents underscore the crucial role that good staircase design can play in prevention of trips and falls. This article outlines the key features of safe staircase design, and how achieving these characteristics can help mitigate risks.
The risk
Falls on stairs claim the lives of over 700 people annually, and over 43,000 people are hospitalised every year as a result of falls on stairs in the home, according to RoSPA.
While it’s important to remember that the NHS highlights that “most falls do not result in significant injuries,” there are simple steps that can be taken to reduce the risk, such as adequate lighting.
However, one of the main factors affecting the ability of a user to navigate a staircase safely is its design. The geometry of the stair, the rise, the going, the position and shape of the treads can affect the ability of the user to safely place their feet and avoid accidents.
There are five key elements in stair design that can help reduce the risk of trips and falls, as described in the following few paragraphs.
Consistent rise & going
A key cause of under-stepping or over-stepping in both ascent and descent is where there is inconsistency in the rise (the height of a step) and going (the horizontal distance between the nosings of two consecutive treads) of a stair. When a person starts to ascend or descend a stair, they subconsciously determine the appropriate movements they need to make with their legs and feet based on the first one or two steps they take. This process, known as ‘proprioceptive feedback,’ makes the user vulnerable to variations in the rise and going of a stair as they expect to step up or down by the same amount throughout the flight. Variations between steps are unexpected and can lead to the user tripping or slipping. For this reason, it is important to allow only small variations between steps of 1% of the design dimensions.
Open rise
Where stairs are designed to have an open rise, the treads should overlap and there should never be horizontal gaps between treads when the stair is viewed on plan. To protect children who may use the stairs, the vertical gaps between treads should be small enough to prevent a 100 mm diameter sphere from passing through.
Handrails
Handrails are essential for safety, allowing users to stabilise themselves quickly in case of a loss of balance. The handrail must be positioned within easy reach to ensure safety at any point on the stairs.
Guarding
To adequately protect users from falling from the side of the stairs, any fall of more than 600 m should be protected by guarding. This should be strong enough to withstand weight and tall enough to stop people from falling over the top. For children’s safety, gaps in the guarding should be small enough to prevent a 100 mm diameter sphere from passing through.
Surface finish
The surface finish or covering of a tread can affect the likelihood of slipping. For example, worn coverings can cause trips. For stairs with a going of 300 mm, slipperiness is less of an issue, but for treads less than 300 mm, slip resistance at the nosing is important. This is where first contact is made in descent and a slip-resistant surface can help turn a potential slip into a slight loss of balance which can be corrected by gripping the handrail.
Driving best practice
At the BWF, we believe that stair safety is of paramount importance and is founded in the design, specification and installation of the staircase. To champion best practice in safe staircase design, the BWF Stair Scheme has a range of guidance documents including two comprehensive design guides which are free to access.
The BWF also has a ‘Overview of Timber Stairs’ e-learning course, which provides an overview of timber stairs, their design, manufacture and installation.
There are many factors that influence the design of a staircase including its location and aesthetic style. But only by ensuring that stairs are designed appropriately and safely can the risk of trips and falls be reduced.
Kevin Underwood is technical manager of the British Woodworking Federation