Part M Door Width Requirements
Minimum effective clear door widths, approach spaces, threshold details, and accessibility categories, referencing Approved Document M: Access to and Use of Buildings, Volume 1 - Dwellings (2015 edition incorporating 2016 amendments).
Minimum Effective Clear Door Widths (AD-M)
| Door Location | M4(1) Visitable | M4(2) Accessible | M4(3) Wheelchair |
|---|---|---|---|
| Principal entrance door | 850 mm | 850 mm | 850 mm |
| Internal doors (straight approach) | 775 mm | 775 mm | 850 mm |
| Internal doors (side approach) | 775 mm | 900 mm | 1,000 mm |
| En-suite / WC door | 775 mm | 775 mm | 850 mm |
| Existing buildings (reasonable provision) | 750 mm | N/A | N/A |
Common Door Leaf Sizes and Effective Clear Widths
| Nominal Door Leaf | Imperial | Approx. Effective Clear Width |
|---|---|---|
| 726 mm | 2'6" | ~670 mm (does NOT meet M4(1)) |
| 826 mm | 2'9" | ~775 mm (meets M4(1) & M4(2) straight) |
| 926 mm | 3'0" | ~870 mm (meets M4(3) straight) |
| 1,026 mm | 3'4" | ~970 mm (meets most M4(3) requirements) |
Approach Space Requirements
| Approach Type | Pull Side Clear Space | Push Side Clear Space |
|---|---|---|
| Straight on (head-on) | 300 mm beside latch | Nil beside latch |
| Side approach (90°) | 300 mm beside latch + 1,200 mm clear | 300 mm beside latch + 1,200 mm clear |
| Threshold level change | Max. 15 mm upstand (bevelled) | Level threshold preferred |
M4 Category Summary
| Category | When Required | Key Features |
|---|---|---|
| M4(1) Visitable | All new dwellings (default) | Level access, entry-level WC, 775 mm clear doors |
| M4(2) Accessible & adaptable | Planning condition only | Step-free, adaptable bathroom, wider corridors (1,050 mm), wheelchair turning space |
| M4(3) Wheelchair user | Planning condition only | Full wheelchair dwelling: 1,200 mm corridors, level-access shower, hoist provision |
Scotland & Northern Ireland
Scotland follows Technical Handbook Section 4.1 (Access to buildings) with its own accessibility standards including the Housing for Varying Needs guidance. Northern Ireland uses Technical Booklet R. Requirements may differ from AD-M, particularly for M4(2) equivalent standards. Always check the relevant jurisdiction.
Related Calculators
Use the Wheelchair Ramp Calculator for access ramps, or the Part M Ramp Gradients reference for ramp specifications.
Always check the latest edition of Approved Documents on the Planning Portal (planningportal.co.uk) as regulations are updated periodically.
How We Calculate This
Frequently Asked Questions
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.