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Accessible housing standards: M4(2) and M4(3) explained
Accessible housing standards sit at the junction between planning and Building Regulations. The planning system can require a proportion of new homes to meet the optional M4(2) or M4(3) standards, while the technical detail is contained in Approved Document M.
The August 2026 NPPF makes this much more important. Policy HO5 says development-plan policies should ensure that no less than 40% of homes on major developments are delivered to M4(2), subject to appropriate exemptions in the development plan, while local evidence should determine the need for M4(3) wheelchair-user homes.
This is separate from the Nationally Described Space Standard. A home can comply with NDSS and still fail an accessibility requirement, or vice versa.
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The three Part M categories
- M4(1) Category 1 — Visitable dwellings: the baseline requirement where no higher optional requirement applies
- M4(2) Category 2 — Accessible and adaptable dwellings: a higher standard intended to make homes accessible to a wider range of occupants and easier to adapt over time
- M4(3) Category 3 — Wheelchair user dwellings: homes which are wheelchair adaptable or wheelchair accessible depending on the requirement imposed
M4(2) and M4(3) are optional requirements in the Building Regulations. They become applicable to individual homes where the planning process requires them.
What changed in the August 2026 NPPF?
HO5 expects development plans to set the proportion of homes on major developments which must meet M4(2) and M4(3). The requirements should meet or exceed evidenced local need and should ensure that at least 40% of homes on major developments meet M4(2), subject to appropriate exemptions set out in the development plan.
For an individual planning application, you still need to identify the development-plan policy applying to the site and how the authority is implementing the new Framework. The NPPF does not mean that every planning permission issued on 18 August 2026 instantly acquired a freestanding 40% planning condition.
How planning and Building Regulations work together
The planning authority does not invent its own version of M4(2) or M4(3). Planning establishes whether the optional requirement applies; Building Regulations and Approved Document M provide the technical route to compliance.
Approved Document M describes M4(2) and M4(3) as optional requirements which apply where the relevant requirement is imposed through the planning process. Where no higher requirement is triggered, M4(1) is the baseline.
What does M4(2) mean in practice?
M4(2) is designed so that a dwelling is accessible and adaptable for a broad range of people, including many older and disabled occupants. It deals with matters such as approach to the dwelling, step-free access, circulation, entrances, sanitary facilities and the ability to adapt the home later.
It is more than simply providing a wide front door. A layout fixed before the access requirement is considered can be difficult and expensive to repair later. Our practical guide to wheelchair accessible homes looks beyond the technical standard at parking, site levels, entrances, circulation and future-proofing a home from the outset.
What does M4(3) mean?
M4(3) is the wheelchair-user standard. Depending on the requirement, a dwelling may need to be wheelchair adaptable or wheelchair accessible from occupation.
That can affect considerably more than the internal floor plan. Parking, approach routes, communal entrances, lifts, private outdoor space, kitchens and sanitary accommodation can all be relevant.
Flats without lifts can be a problem
The optional standards require step-free access. Government guidance recognises that this can affect non-lift-served multi-storey development. Where step-free access cannot viably be achieved, planning authorities need to take that into account when setting and applying policies.
Do not therefore assume that a percentage requirement can simply be spread randomly through every floor of a block. The location of compliant homes needs to be designed intentionally.
Specialist housing
Policy HO9 goes further for specialist housing for older or disabled people. It says this accommodation should be delivered to M4(2) or M4(3) accessibility standards and located where residents can reach frequently used services safely and conveniently.
That makes accessibility a planning issue from the earliest site and layout stage rather than something to be left for Building Control at the end.
Accessible housing is not the NDSS
The NDSS controls internal space through dwelling type, bedspaces, storage, bedroom dimensions and ceiling height. Part M controls accessibility and adaptability. Both can apply to the same home.
Our wider housing space standards guide explains where NDSS, HMO room sizes and Building Regulations fit together.
Design checklist
- Check the local plan requirement before fixing the site layout
- Identify which dwellings are intended to meet M4(2) and M4(3)
- Check step-free access from the site boundary, parking and communal areas
- Coordinate planning drawings with Approved Document M
- Do not use NDSS compliance as evidence of Part M compliance
- For flats, consider lift provision and the distribution of accessible homes early
- Read the actual planning condition before construction
Relevant policy and standards
- National Planning Policy Framework, August 2026 — particularly PM13, HO5 and HO9
- Approved Document M: access to and use of buildings
- Planning Practice Guidance: housing optional technical standards
Other Housing Sections
Accessible Housing Standards Page Updated: 30th August 2026