Floors and accessibility: thresholds, LRV and slip

At a glance

Approved Document M volume 2, 2015 edition incorporating 2020 and 2024 amendments, for use in England, read 7 Nov 2026. Buildings other than dwellings only.

What Part M asks of a floor

Approved Document M is the statutory guidance on access to and use of buildings in England. Volume 2 covers buildings other than dwellings: hotels, restaurants, offices, shops and the like. It says very little about floors as such, and a few things precisely. It does not say a floor must have a given luminance contrast, and it gives no slip value. What it does give is a short list of conditions on thresholds, level changes and floor surfaces, and a definition of visual contrast that is used wherever the document asks two surfaces to contrast. A floor specification meets Part M by meeting those conditions and by being the right finish for the people who use the space.

The volume also points to BS 8300 for detailed guidance (for example on surface finishes, 4.32 note, and on slip resistance, 5.18 note). BS 8300-2:2018 is the current edition (BSI listing seen in our slip and Part M sheets; the 2009 edition is withdrawn). The text of the standard was not read for this sheet, so no figure from it is given.

Two limits on the scope. The sheet is for England and for buildings other than dwellings. Dwellings are in volume 1 (not read), and Scotland, Wales and Northern Ireland have their own documents (not read). A hotel guest room, a restaurant and a members’ club are in this volume; a private house is not.

Visual contrast and LRV

Part M defines visual contrast in terms of light reflectance value (LRV), the total quantity of visible light a surface reflects, from 0 (black) to 100 (perfect white). Two surfaces contrast visually if the difference in LRV between them is more than 30 points. Where the illuminance on the surfaces is above 200 lux, a difference of at least 20 points is the minimum. For door opening furniture that projects beyond the face of the door, or otherwise creates differentiation and shade, at least 15 points is considered adequate (paragraph 0.26, printed p.15). The definition refers on to Colour, contrast and perception (University of Reading) for further information.

For a floor this matters in the places where the document asks for contrast. Examples in volume 2: sanitary fittings and grab bars against the wall and floor finishes, and the wall against the floor in the same room (5.4 k); internal doors and their surroundings (3.8, 3.10); and door furniture (2.17). Paragraph 4.32 adds that floor, wall and ceiling finishes help visually impaired people appreciate the boundaries of a space and identify routes. We did not find a sentence in this volume that requires the floor and walls of every corridor to differ by 30 points, so a designer should ask the accessibility adviser which relationships the project must meet rather than assume.

Finding the LRV of a floor. The LRV is a measured property, tested to BS 8493 (Light reflectance value of a surface: method of test, current edition 2008+A1:2010, with a revision out for comment) and not estimated from a colour name. BSI’s draft says the method is for a sample, not for measurement on site. LRVs for timber and stone vary by species, stain, finish and batch, and we found no published table of values for common stones and timbers, so none is given here. Ask the partner to measure the finished sample to BS 8493, and put the measured value in the schedule.

Thresholds, landings and changes of finish

The paragraph on accessible entrances (2.7) sets four conditions for the floor at and just inside the door. A level landing at least 1,500 x 1,500 mm sits in front, clear of any door swing, in a material that does not impede wheelchairs. The threshold is level or, if a raised threshold cannot be avoided, no more than 15 mm in total, with the minimum number of upstands and slopes and any upstand over 5 mm chamfered or rounded. Floor surfaces just inside do not impede wheelchairs (the document gives coir matting as an example to avoid) and changes in floor material do not create a trip hazard. Where a mat well is provided the mat is level with the floor around it. Entrance lobbies repeat the last three points (2.29 e, f, g) and add that the floor should help to remove rainwater from shoes and wheelchairs (2.29 f), and that rainwater is better not carried into the building where it becomes a slip hazard, for example by cleaning mats (2.28).

For a floor designer this is the junction detail between outside, threshold and inside. It is also the junction between two finishes: stone to timber, timber to carpet, or a mat well to any of them. ‘Level’ in Part M means at most a 1:60 gradient (0.26), and the 15 mm and 5 mm limits are total heights, so the build-up of the two floors on each side needs to be set out so they meet at a common level. See floor transitions and movement joints for the junction types and floor build-up heights and finished floor levels for the heights.

Slip, glare and the finish

Volume 2 asks for slip-resistant floors in reception (3.6 g) and in corridors and passageways (3.14 k), and for the floors of changing areas next to showers, showers (also self-draining) and accessible bathrooms to be slip resistant when dry or wet (5.18 i, o; 5.21 c). It gives no value and no test. A note to 5.18 says HSE guidance on slip resistance is in Annex C of BS 8300, which is the 2009 edition, now withdrawn; where that guidance sits in BS 8300-2:2018 we did not confirm. Our slip resistance for floors sheet covers the pendulum test, the sliders and the wording, and stone and timber in wet areas the bathroom and spa case.

Slip resistance and contrast pull in different directions in one place. A polished stone is bright, glossy and reflective, so it risks glare as well as a low wet PTV; Part M asks for glare and reflection from shiny surfaces to be avoided where visual acuity is critical (4.32). The same stone honed is quieter in both respects, and see natural stone finishes for how the finishes compare.

Patterns

Corridors in a hotel or club often carry a pattern floor, and paragraph 3.14 (j) asks that floor finishes with patterns that could be mistaken for steps or changes of level are avoided. Paragraph 4.32 asks that large repeating patterns are avoided where visual acuity is critical. The volume does not say which patterns, how large or how contrasting. A strongly contrasting chequer, a bold stripe across the direction of travel or a border that reads as a step are the usual concerns; a plain herringbone or chevron in a single timber is not obviously within it, but that is our reading, not Part M’s. Show the pattern, the contrast between the elements and the lighting to the accessibility adviser at design stage, and see the pattern atlas for the patterns.

What the floor schedule holds

A floor schedule that meets Part M for this volume holds, for each space:

• the LRV of the finished floor, measured to BS 8493 on the finished sample (a value from the partner, not a colour name), and of the wall and the fittings it must contrast with;
• the threshold and every change of floor: type, total height, upstand profile and what is on each side, at the finished levels;
• the slip method and result on the finished sample, wet, with the standard and slider named (see the slip sheet), and who set the target;
• the finish and pattern: gloss level, pattern size and the contrast within it, for the adviser to review;
• the mat well and mat: depth, so that the mat is level with the adjacent floor.

Floor finish [ref] in [space] is to have a measured light reflectance value of [ ] (BS 8493) and to differ from [wall finish ref, LRV ] by not less than [ ] points, as required by Approved Document M volume 2 paragraph [5.4 (k) / other], the illuminance on the surfaces being [ ] lux. The partner is to submit the measured LRV of the finished sample for approval before production.

Entrance threshold at [door ref]: [level / raised not more than 15 mm in total, upstands over 5 mm chamfered or rounded] as drawing [ref], with a level landing not less than 1,500 x 1,500 mm clear of door swings. Changes of finish at [locations] are to be flush at the finished level, with a transition strip [type] as drawing [ref]. Mat well [depth] so that the mat is level with the adjacent floor.

Slip resistance of [finish] to be tested wet to [method and edition] on a production sample as laid, result [ ] before fabrication, target set by [designer / duty holder] (see the slip clause). The pattern [ref] in [corridor] is to be reviewed by [accessibility adviser] against Approved Document M volume 2 paragraphs 3.14 (j) and 4.32 before the sample is approved.

Standards and sources

• Approved Document M volume 2: Access to and use of buildings other than dwellings, 2015 edition incorporating 2020 and 2024 amendments (England): read in full text 7 Nov 2026; paragraphs 0.26, 2.6 to 2.7, 2.28 to 2.29, 3.6, 3.14, 4.32, 5.4, 5.18, 5.21.
• BS 8300-2:2018: BSI listing: current (2009 edition withdrawn), as seen in our slip and Part M sheets' notes, 5 Nov 2026. Text not read.
• BS 8493:2008+A1:2010: LRV method of test: current on BSI Knowledge (seen 7 Nov 2026); a draft revision is open for comment. Text not read.
• Our sheets: Slip resistance for floors; Floor transitions and movement joints

Questions we are asked

What LRV difference does Part M need between a floor and a wall?

Approved Document M volume 2 defines visual contrast as a difference of more than 30 LRV points between two surfaces, at least 20 points where the illuminance on them is above 200 lux, and at least 15 points for door furniture that projects from the door (paragraph 0.26). It uses the definition where it asks for contrast, for example for sanitary fittings against wall and floor finishes. We found no sentence requiring every floor and wall to differ by 30 points, so ask your access adviser which relationships the project must meet.

How high can a threshold be?

Level, or if a raised threshold is unavoidable a total of not more than 15 mm, with a minimum number of upstands and slopes and any upstand above 5 mm chamfered or rounded (paragraph 2.7 e). That is England, buildings other than dwellings. A level threshold is preferred (2.6).

What is the LRV of oak or marble?

It varies with species, stain, finish and batch, and we found no published table of values we could rely on. Ask the partner to measure the finished sample to BS 8493 and record the value in the schedule.

Is there a required slip value for accessible floors?

Not in Approved Document M volume 2: it asks for slip-resistant floors in reception, corridors, changing areas, showers and accessible bathrooms, and gives no value. See our slip resistance sheet for how to specify a test and a target.

Can I use a patterned floor in a corridor?

Paragraph 3.14 (j) asks that patterns that could be mistaken for steps or changes of level are avoided, and 4.32 asks that large repeating patterns are avoided where visual acuity is critical. The document does not name patterns, so take the pattern, its contrast and the lighting to your access adviser at design stage.

Does this apply to a private house or to Scotland and Wales?

No. This sheet is about Approved Document M volume 2 for England and buildings other than dwellings. Dwellings are in volume 1 and the other nations have their own documents, which we have not read.