The UK’s domestic staircase rules have remained largely unchanged for more than a decade, but that looks set to shift with the publication last month (October 2025) of government-commissioned research carried out to support potential updates to Approved Document K (AD K).
While BS 5395-1 (2010) remains current, the focus is on the gap between this standard and the statutory guidance – Approved Document K, with industry and regulators looking to better align this with safety evidence.
The new report, published by the Department for Levelling Up, Housing and Communities (DLUHC), specifically looks at domestic stairs, focussing on, step dimensions, tolerance in those dimensions, and the question of second handrail provisions for narrower stairs. The objective is to determine whether changes could reduce the risk of injury or death from stair falls, without imposing an excessive burden on builders and developers.
In this blog we aim to explain what’s being reviewed, what the current limits are, and what changes might mean for housebuilders and contractors. Nothing has changed yet – it’s about understanding what might come.
Under current AD K guidance for “private stairs” in a dwelling the requirements are:
Rise: between 150 mm and 220 mm
Going (tread depth): typically 220 mm to 300 mm
Pitch: must not exceed 42°
These parameters have remained largely unchanged for decades, providing flexibility but also allowing for quite steep, compact flights — particularly in smaller homes.
The new DLUHC-commissioned report provides evidence that larger going dimensions dramatically improve safety
In one analysis, stairs with a going of around 190–200 mm showed up to six times the accident risk of those with goings near 250–260 mm. In controlled testing, a stair with a 275 mm going reduced the predicted likelihood of a severe fall from once every four years to once every 146 years for a typical user.
The report stops short of prescribing new limits, but the trend is clear: the deeper the tread, the safer the stair.
Current AD K allows risers up to 220 mm, with no formal preference for lower values.
The evidence suggests that smaller risers, between 150 mm and 200 mm, are safer and more comfortable for a wider range of users.
Rises under 100 mm can create trip hazards on ascent, while taller rises fatigue users more quickly — especially older occupants. The optimal balance, according to the gathered data, lies firmly in the mid to lower portion of the current range.
Approved Document K already states that rises and goings within a flight should be consistent — but does not specify how much variation is acceptable.
The report strengthens that point, showing that even small differences between steps increase the misstep risk, so there is scope for a specified tolerance limit.
At Stairways Midlands, our precision manufacturing processes already deliver consistency across each flight.
Under current AD K, a handrail is required on at least one side of any flight; both sides are only recommended when the width exceeds 1000 mm.
The new report explores whether adding a second handrail on narrower domestic stairs could improve safety. Findings suggest that dual handrails enhance stability and confidence, particularly for older users or when carrying loads.
While these findings don’t yet alter regulatory requirements, they represent a clear direction of travel: toward greater safety, comfort and dimensional precision in domestic stair design.
Deeper treads mean longer stair runs, so the flight takes up more horizontal space. For example, with 30mm added to each tread on a typical 13-tread flight, this works out as an extra 390mm. For 15-tread flights this is an extra 450mm.
This means buildings would need wider or longer well openings in the floor, so joist positions and structural layouts may need to shift. The change would also result in less usable floor area upstairs and down, especially in compact homes. Landing positions and headroom may also need a redesign to maintain a 2-metre clear headroom. There may also be slight cost and material increases for longer strings, handrails, and possibly more balustrade material.
For developments with tight footprints or standardised house types, even 300–400 mm extra run per flight can have knock-on effects on room layouts.
Nothing is changing immediately, as the government is still reviewing the evidence, but it is worth keeping a close eye on this.
As one of the UK’s leading stair manufacturers, we welcome a focus on stair safety. You can trust that at Stairways Midlands we will continue to monitor developments and keep our clients informed once proposals become official. If you have any questions regarding these regulations, get in touch at enquiries@stairways.co.uk
Or to read the report in full, see:
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