Approved Document M and Stair Nosings: The 55mm Contrasting Band

Approved Document M is where the stair nosing contrast requirement actually lives. If you specify one number from the Building Regulations for a commercial stair, this is it: a 55mm × 55mm contrasting band across the tread and the riser.

What Part M covers

Approved Document M is titled Access to and Use of Buildings. Where Part K asks whether a stair is dimensionally safe, Part M asks whether people can actually use it — including people with reduced vision, reduced mobility, or both.

For stairs, the central provision is that the leading edge of each step should be made apparent. A band of contrasting material on the tread and the riser is how that is achieved, and 55mm on each face is the dimension given.

Who it applies to

Part M distinguishes between dwellings and everything else. The 55mm contrasting band applies to buildings other than dwellings — offices, shops, schools, hospitals, transport, hospitality, public buildings.

Communal areas in blocks of flats are treated separately from the dwellings themselves, so a stair in a shared entrance hall is not automatically outside scope just because the building is residential. Check what applies to your project rather than assuming.

Why 55mm on both faces

Two faces, two viewing angles. Descending a flight you see the tread band; ascending, or approaching from below, you see the riser band. A nosing that marks only the tread disappears on the way up.

That is why a 55mm × 55mm profile is the specification workhorse for non-domestic stairs, and why a slim decorative trim — however smart — does not satisfy Part M on its own. It is also worth checking on tile-in profiles, which are often deliberately slim and may not achieve the band.

Contrast is measured, not judged

Part M asks for the edge to contrast. It is BS 8300-2:2018, referenced by Part M rather than being law itself, that puts a number on how much: at least 30 points of Light Reflectance Value between the nosing and the surrounding tread.

This is where specifications quietly fail. Two colours that look clearly different to a sighted person in good light can measure within a few LRV points of each other — mid-tone greys against brushed aluminium are a classic near-miss, and patterned carpet is worse. Ask for the LRV figure and do the subtraction. Our LRV contrast calculator will check a combination before you commit.

More on BS 8300 and LRV contrast.

The most common Part M mistakes

• Matching the nosing to the floor. Specifying a nosing that blends with the covering is the exact opposite of what Part M asks for. Contrast is the requirement, not coordination.
• Marking the tread only. The band is needed on the riser too.
• Judging contrast by eye. Use measured LRV values.
• Assuming a slim profile qualifies. Check the dimensions against 55mm before specifying on a non-domestic stair.
• Confusing it with Part K. Part K is geometry — going, rise and the 25mm projection limit. More on Part K.

Part M and the Equality Act

These are separate but related. Part M is Building Regulations guidance, engaged by building work. The Equality Act 2010 creates a continuing duty to make reasonable adjustments so disabled people are not put at a substantial disadvantage, and it applies whether or not any building work is happening.

A stair built before current guidance is not automatically unlawful, but a service provider who has never considered whether its stairs are usable has not thought about the duty. Meeting the Part M band is the normal way of demonstrating that you have.

Note also that the Equality Act replaced the Disability Discrimination Act, so "DDA compliant" describes a market convention rather than a live legal standard.

Frequently asked questions

What size does a Part M stair nosing need to be?
55mm on the tread and 55mm on the riser — a 55mm × 55mm band. Profiles are widely available in exactly that dimension for this reason.

Does Part M apply to my house?
The contrasting band provision applies to buildings other than dwellings. Communal areas of flats are treated differently from the dwellings themselves.

How much colour contrast is enough?
At least 30 points of Light Reflectance Value difference between nosing and tread, per BS 8300-2:2018. Measure rather than eyeball it.

Can I use a slim tile-in profile on a commercial stair?
Only if it achieves the 55mm band, and many slim profiles do not. Check the dimensions before specifying.

Does Part M say anything about slip resistance?
Part M is about access and usability. Slip resistance is driven by regulation 12 of the Workplace Regulations 1992 and measured by the pendulum test. More on slip testing.

Browse profiles dimensioned for the Part M band in the DDA and accessibility range, or see the full compliance guide.