Building Regs Part M: Accessible and Inclusive Design for New Dwellings and Buildings Open to Visitors

Quick Answer: Approved Document M sets the accessibility requirements for new buildings in England. For dwellings (Volume 1), every new home must meet the baseline category M4(1) — Visitable: level or gently sloping approach, a step-free principal entrance, a WC at entrance level, and a minimum 775mm clear opening width on doors. The higher standards M4(2) Accessible and Adaptable and M4(3) Wheelchair User are optional requirements that only apply when a local plan or planning condition imposes them. Volume 2 covers buildings other than dwellings — accessible entrances, ramps, lifts, accessible WCs, and Changing Places toilets.

Summary

Part M of the Building Regulations is about getting in, getting around, and using a building regardless of mobility, age, or disability. It is split into two Approved Documents: Volume 1: Dwellings and Volume 2: Buildings other than dwellings. The two documents use different language and different numbers, so the first job on any project is to work out which one applies.

The biggest misconception among tradespeople is that "Part M only matters for wheelchair housing." In fact the baseline category M4(1) applies to every new dwelling in England and is not optional — a developer cannot opt out. The higher categories M4(2) and M4(3) are different: they are optional requirements in the regulations, meaning they only bite when a local planning authority adopts them in its Local Plan and applies them as a planning condition. So whether a new house needs an accessible WC with a 1500mm turning circle depends not on Building Control but on the planning consent.

For the working builder, Part M shows up most often on new-build housing (door widths, level thresholds, entrance-level WCs, socket and switch heights) and on commercial fit-outs (accessible entrances, ramps, lift provision, accessible and Changing Places toilets). Part M does not generally apply to ordinary work on an existing dwelling — but it does apply to the new elements of an extension, and to a material change of use (e.g. converting an office to flats). Get the threshold detail or the door width wrong on a new build and Building Control will not sign off.

Key Facts

• Two volumes — Approved Document M Volume 1 = dwellings; Volume 2 = buildings other than dwellings. They are separate documents with separate requirements.
• M4(1) Category 1 (Visitable dwellings) — mandatory baseline for all new dwellings. Covers approach, entrance, circulation, and an entrance-level WC.
• M4(2) Category 2 (Accessible and adaptable dwellings) — optional requirement; applied only where a planning condition requires it. Broadly equivalent to the old Lifetime Homes standard.
• M4(3) Category 3 (Wheelchair user dwellings) — optional requirement; the highest standard, applied via planning condition (often for a percentage of affordable units). Two sub-types: M4(3)(2a) wheelchair adaptable and M4(3)(2b) wheelchair accessible.
• Door clear opening width — minimum 775mm clear opening width for internal doors on the entrance storey in M4(1) where the corridor approach is 900mm+. Wider clearances apply at M4(2)/M4(3).
• Level/gently sloping approach — the approach from the boundary/parking to the principal entrance must be step-free, level, or gently sloping. Maximum cross-fall and gradients are set out in ADM Vol 1.
• Accessible threshold — the principal (or alternative accessible) entrance threshold should be level; an upstand of no more than 15mm is permitted to maintain weather resistance.
• Entrance-level WC — M4(1) requires a WC at entrance level usable by a visitor; M4(2) requires it to meet larger dimensions for adaptability.
• Socket and switch heights — in M4(1)/M4(2) dwellings, wall-mounted switches, sockets and consumer-unit controls should be 450mm to 1200mm above finished floor level so they are reachable.
• Volume 2 accessible entrance — the principal entrance (or an alternative accessible entrance) must be approachable and usable by wheelchair users; door opening forces and clear widths are specified.
• Ramps (Volume 2) — gradients depend on the going (length) of each flight: steeper ramps are allowed only for short rises. See the ramp table below and cross-check Part K, which also governs ramps.
• Lifts (Volume 2) — a passenger lift is the preferred means of vertical access; where a passenger lift is not provided, a lifting platform may be acceptable for limited rises.
• Accessible WC (Volume 2) — unisex accessible (wheelchair) WC dimensions, grab rail layout (left/right-hand transfer), and door arrangement are specified in ADM Vol 2 diagrams.
• Changing Places (Volume 2) — required in certain large buildings used by the public (e.g. large retail, stadia, services) under the 2021 amendment; provides an adult-sized changing bench and a hoist in addition to standard accessible WCs.
• Visual contrast — a minimum 30-point Light Reflectance Value (LRV) contrast between key surfaces (e.g. door against wall, sanitaryware against floor) aids partially sighted users in Volume 2 and in higher dwelling categories.
• Part M is not a competent-person self-cert area — compliance is demonstrated to Building Control as part of the overall plans check and completion inspection.

Quick Reference Table

Detailed Guidance

Which volume and category applies?

Start with the building type. A house, flat, or maisonette = Volume 1. Anything else open to the public or used for work = Volume 2.

For dwellings, the planning permission tells you the category. If the decision notice or Local Plan policy requires "M4(2)" or "a proportion of M4(3) units," that is a planning condition and is enforced by the planning authority — Building Control then checks the build against that category. If the consent is silent, the dwelling defaults to M4(1), which is never optional. Always read the decision notice before pricing the internal joinery and sanitaryware, because M4(2)/M4(3) drive door widths, corridor widths, and bathroom sizes that are expensive to retrofit.

M4(1) — Visitable dwellings (the baseline)

M4(1) is about a visitor being able to reach and enter the home and use a WC. The four practical hits for a builder:

• Approach — a step-free route from the parking space / boundary to the principal entrance, level or gently sloping. Where the plot makes a level approach impossible, an alternative accessible entrance route can be used.
• Entrance — a step-free principal entrance with a level threshold (max 15mm upstand to keep weather resistance). The door must give the required clear opening width.
• Circulation — corridors and internal doorways on the entrance storey sized so a visitor using a walking aid can move through. The minimum door clear width pairs with the corridor width (a narrower corridor needs a wider door).
• WC — a WC at entrance level. In M4(1) this need only be usable by a visitor; it does not need a wheelchair turning circle.

M4(2) and M4(3) — the optional higher categories

M4(2) Accessible and adaptable is broadly the old Lifetime Homes idea: the home works for most people now and can be cheaply adapted later (e.g. structure that allows a future stairlift or through-floor lift, a bathroom that can take grab rails, wider circulation). It only applies when planning requires it.

M4(3) Wheelchair user is the highest standard, split into:

• M4(3)(2a) Wheelchair adaptable — built so it can be easily adapted to suit a wheelchair user.
• M4(3)(2b) Wheelchair accessible — fully accessible on completion (turning circles, accessible kitchen and bathroom, accessible parking and approach).

These categories carry significantly larger room and circulation dimensions. Do not assume them — confirm from the planning consent which specific units must meet which category.

Volume 2 — buildings open to visitors

For offices, shops, surgeries, leisure and similar, the headline provisions are:

• Accessible entrance — the principal entrance, or a clearly signed alternative, must be usable by wheelchair users. Manual door opening forces and clear widths are specified.
• Ramps — provided where there is a change of level that a wheelchair user cannot negotiate. Gradients are length-dependent (see table below) and ramps need landings, handrails, and edge protection. Part K also governs ramp guarding.
• Lifts — a passenger lift is the preferred vertical-access solution in multi-storey buildings. Where it is not reasonable to provide one, a lifting platform may suit smaller rises.
• Accessible (unisex) WCs — at least one wheelchair-accessible WC with the correct grab-rail layout and transfer space; larger buildings need more, and a mix of left/right-hand transfer layouts.
• Changing Places toilets — required in certain large public buildings (introduced by the 2021 amendment to ADM Vol 2). These add an adult changing bench and ceiling hoist on top of standard accessible WCs.

Ramp gradients (Volume 2 / Part K)

Part M and existing buildings

Part M is light-touch on existing dwellings. Ordinary repair, replacement, or improvement work on an existing home does not trigger Part M. The triggers are:

• Extensions — the new parts must consider reasonable provision (e.g. you should not make an existing accessible WC less accessible).
• Material change of use — converting a building into dwellings or into a building covered by Volume 2 brings the relevant Part M requirements into play for the changed building.

In commercial work, accessibility is also a duty under the Equality Act 2010 (reasonable adjustments), which can require improvements even where Building Regs do not — these are separate legal regimes that often overlap.

Frequently Asked Questions

Is an accessible/wheelchair WC required in every new house?

No. Every new dwelling needs an entrance-level WC under M4(1), but it only has to be visitable — usable by a visitor, not necessarily a wheelchair turning circle. A full wheelchair-accessible bathroom with a 1500mm turning circle is only required where planning has imposed M4(3) on that unit. Check the decision notice.

What is the minimum door width under Part M for dwellings?

For M4(1), the minimum internal clear opening width is 775mm where the corridor approach is at least 900mm wide. Note "clear opening width" is measured with the door open at 90°, not the structural opening — an 838mm (33") door leaf typically gives the required clear width once the leaf thickness and ironmongery are accounted for.

Does Part M cover socket and light switch heights?

Yes, in dwellings. Wall-mounted controls — switches, sockets, the consumer unit, and similar — should sit within the 450mm to 1200mm band above finished floor level so they are reachable by most people. This is one of the most commonly missed items on first fix.

Is a level threshold the same as a flush threshold?

Almost. Part M allows a threshold upstand of up to 15mm to maintain weather resistance and drainage — a genuinely flush (0mm) detail is not required and is often a leak risk. Use a low-profile accessible threshold and a drainage channel rather than fighting for an absolute zero step.

Who enforces M4(2) and M4(3)?

The local planning authority sets whether the optional categories apply, through Local Plan policy and planning conditions. Building Control then checks the build against whichever category the consent requires. If you build to M4(1) when the consent required M4(2), that is both a Building Regs failure and a planning breach.

Regulations & Standards

• Approved Document M, Volume 1: Dwellings — accessibility of new dwellings; categories M4(1), M4(2), M4(3).

• Approved Document M, Volume 2: Buildings other than dwellings — accessible entrances, ramps, lifts, sanitary accommodation, Changing Places (2021 amendment).

• Building Regulations 2010 (as amended) — the legal basis; Requirement M and the optional requirements are in Schedule 1.

• BS 8300-1 and BS 8300-2:2018 — design of an accessible and inclusive built environment (external environment / buildings); the underpinning best-practice standard referenced for Volume 2 design.

• Equality Act 2010 — separate duty on service providers/employers to make reasonable adjustments; overlaps with Part M in commercial buildings.

• GOV.UK — Approved Document M (access to and use of buildings) — full text of Volumes 1 and 2.

• GOV.UK — Changing Places toilets in buildings (2021 amendment) — Volume 2 Changing Places requirement.

• Planning Portal — Access to and use of buildings — practical overview of Part M categories.

• legislation.gov.uk — Equality Act 2010 — reasonable adjustments duty.

• part m access — companion article on Part M level thresholds, door widths and accessible bathrooms (more detail on accessible bathroom dimensions).

• part k falls — ramps, stairs and guarding; ramp gradients overlap with Part M Volume 2.

• building regs overview — how Part M sits alongside the other Approved Documents.

• planning vs building regs — why M4(2)/M4(3) are set by planning, not Building Control.