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Part M Access: M4(1), M4(2) and M4(3) Explained

M4(1), M4(2) and M4(3) sound similar but set quite different expectations for a home's accessibility.

Part M of the Building Regulations in England covers access to and use of buildings. Its guidance is published in Approved Document M, in two volumes. For housing, Part M introduces three categories that can significantly affect layouts.

Volume 1: dwellings

Volume 1 sets out three categories:

• M4(1) visitable dwellings: the default requirement, allowing most people, including some wheelchair users, to visit
• M4(2) accessible and adaptable dwellings: an optional requirement, providing features that make the home suitable for a wide range of occupants and easier to adapt
• M4(3) wheelchair user dwellings: an optional requirement, either wheelchair adaptable or wheelchair accessible

Optional requirements

M4(2) and M4(3) are optional requirements. They apply when a planning condition requires them. Many local plans set requirements for a proportion of new homes. Check planning conditions carefully, as they determine which category applies to each dwelling.

Wheelchair adaptable versus accessible

M4(3) has two sub-categories. Wheelchair adaptable dwellings can be easily adapted for a wheelchair user. Wheelchair accessible dwellings are suitable for a wheelchair user from the start. Planning conditions usually specify which is needed.

What affects layouts

Higher categories involve requirements such as:

• Step-free approach routes
• Wider doorways and corridors
• Clear turning spaces
• Bathroom and kitchen layouts with clear spaces
• Bedroom clear zones
• Provision for future adaptations, such as lifts or hoists

These requirements affect room sizes and layouts, so they should be considered from early design.

Volume 2: buildings other than dwellings

Volume 2 covers access to non-domestic buildings, including approach, entrances, horizontal and vertical circulation, toilets and facilities. BS 8300 provides more detailed design guidance.

What drawings should show

• The category of each dwelling
• Approach routes and gradients
• Door widths and clear openings
• Turning circles and clear zones
• Enlarged bathroom and kitchen plans
• Parking spaces where required

Compliance checklists

Many teams use checklists against the Approved Document requirements for each category. Building control may ask for them.

Wider duties

The Equality Act 2010 places duties on service providers and employers that can affect non-domestic buildings beyond the minimum requirements.

Check against the space standards

1. 01Volume 1: dwellings
2. 02Optional requirements
3. 03Wheelchair adaptable versus accessible
4. 04What affects layouts
5. 05Volume 2: buildings other than dwellings
6. 06What drawings should show

Coordinate with the planning team

Planning conditions and affordable housing requirements often set how many homes must meet each category. Agree the schedule of M4(2) and M4(3) homes early, mark it on plans and keep it updated as the scheme develops.

Understanding Part M categories early helps avoid redesigns when planning conditions require accessible or wheelchair user homes.

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