The 100mm Gap rule

The 100mm Gap Rule

In the UK there are many rules and regulations governing staircases and their design. These are in place to ensure safety standards and to inspire confidence to the user.

One of these regulations relates to the gaps between steps on open staircases and any gaps between spindles. The regulation states that a 100mm sphere must not be able to pass through any opening in the guarding of the stair or between the steps. This is to prevent small children sliding through gaps and becoming stuck. It does stipulate that this requirement is for buildings whose ‘stairs are likely to be used by children under 5’ but we find that the regulation is generally enforced by all building inspectors when dealing with domestic dwellings and even in some commercial settings.

Given this regulation is fairly unique to northern Europe, many of the staircases that pop up on internet images searches do not comply to UK regulations. This can make things a little confusing when looking for inspiration for your new staircase.

As the present trend in the UK is for open and light staircase where does this leave us? Staircases with open risers are supplied the length and breath of the UK and are perfectly acceptable to building control providing they adhere to the 100mm gap rule. There are several ways we can adapt our staircases to conform whilst maintaining their transparent appearance.

The options below feature on our model 500 staircase. The balustrade on this design consists of vertical spindles or glass panels.

Staircase riser infill options

Double tread thickness -100mm

Full or half glass upstand

Steel U shaped riser bar

Integrated L shaped down-stand to tread

For more information on the 100mm gap rule or any questions about any technical aspect, please get in touch.  We are on 01794 522444 or email