Staircase Regulations UK: Approved Document K for Homes
In England, Approved Document K (2013 edition) allows a private stair in a house a rise of 150 to 220 mm and a going of 220 to 300 mm, with a pitch of no more than 42° and twice the rise plus the going between 550 and 700 mm (Table 1.1). Headroom must be at least 2 m, or 1.9 m at the centre of the stair falling to 1.8 m at the side in a loft conversion (paragraphs 1.11 and 1.13). Handrails sit 900 to 1000 mm above the pitch line, and guarding on stairs and landings must be at least 900 mm high (1.34, Diagram 3.1).
Summary table
| Rule | Metric | Imperial | Approved Document K |
|---|---|---|---|
| Rise, private stair | 150–220 mm | 5 15/16–8 5/8 in | Table 1.1 |
| Going, private stair | 220–300 mm | 8 11/16–11 3/4 in | Table 1.1 |
| Pitch, maximum | 42° | 42° | Table 1.1, note 1 |
| 2R + G | 550–700 mm | 21 11/16–27 1/2 in | Table 1.1 |
| Headroom | 2 m | 78 3/4 in | 1.11, Diagram 1.3 |
| Headroom, loft conversion: centre / side | 1.9 m / 1.8 m | 74 13/16 / 70 7/8 in | 1.13, Diagram 1.4 |
| Landing width and length | at least the width of the flight | – | 1.20 |
| Handrail height above pitch line | 900–1000 mm | 35 7/16–39 5/16 in | 1.34 |
| Handrails on both sides | stairs 1000 mm wide or more | 39 5/16 in or more | 1.34 |
| Guarding required where the drop exceeds | 600 mm | 23 9/16 in | 1.41 |
| Guarding height, stairs and landings | 900 mm | 35 7/16 in | Diagram 3.1 |
| Gaps in guarding (children under five) | no 100 mm sphere | 3 7/8 in | 1.39 |
| Open risers: tread overlap / gap | 16 mm minimum / no 100 mm sphere | 11/16 in / 3 7/8 in | 1.9 |
| Tapered tread at narrow end, minimum | 50 mm | 2 in | Diagram 1.9 |
Imperial values are rounded to 1/16 in on the safe side.
Who Approved Document K applies to
Approved Document K is statutory guidance on the Building Regulations 2010 for England. The 2013 edition took effect on 6 April 2013 and is the edition published on GOV.UK today. It sets three stair categories; a private stair is "a stair intended to be used for only one dwelling" (Appendix A). Requirement K1 covers stairs and steps that are part of the building, such as entrance steps, but not steps on land leading to it (0.3). Following the guidance gives a presumption of compliance; other solutions can be agreed with building control.
Rise, going and the 42° pitch (Table 1.1)
The rise is the height between consecutive treads. The going is the depth of a tread less any overlap with the tread above, measured nosing to nosing (Diagram 1.1). The rise and going must be consistent throughout a flight (1.5).
The three limits work together, so check all of them. A 220 mm rise on a 220 mm going gives 2R + G = 660 mm, inside the range, but a 45° pitch, which fails. With a 220 mm going the rise can be at most about 198 mm (220 × tan 42°); with a 220 mm rise the going must be at least about 245 mm. Common mistake: taking the maximum rise and the minimum going from the table.
Headroom (1.11 to 1.13)
Provide at least 2 m of clear headroom measured above the pitch line and above landings (Diagram 1.3). In a loft conversion without room for 2 m, 1.9 m at the centre line of the stair, reducing to 1.8 m at the side, is accepted (Diagram 1.4).
Width (1.16)
Approved Document K sets no general minimum width for a private stair. The only stair width it gives for dwellings is 900 mm, for stairs within the entrance storey where a severely sloping plot forces a change of level (1.16). If a planning condition requires optional requirement M4(2), Approved Document M Volume 1 asks for a stair from the entrance storey at least 850 mm wide, measured 450 mm above the pitch line (2.23c). Width still matters: landings and handrails depend on it.
Landings (1.20 to 1.24)
Provide a landing at the top and bottom of every flight, at least as wide and as long as the smallest width of the flight (1.20). It can include part of the floor, must be clear of permanent obstructions and must be level; a landing formed by the ground may slope up to 1:60 if paved or otherwise firm (1.21, 1.22). In a house, a door may swing across the bottom landing only if it leaves at least 400 mm clear in front of the first step (1.24, Diagram 1.8).
More than 36 risers in consecutive flights need at least one change of direction of at least 30° (1.17, Diagram 1.6). The 12- and 16-riser limits per flight in 1.18 apply to buildings other than dwellings, not to a private stair.
Handrails (1.34)
Position the top of the handrail 900 to 1000 mm above the pitch line, or above the floor on landings. The handrail may form the top of the guarding if the heights match. Stairs 1000 mm wide or more need a handrail on both sides. The 1998 edition, still used in Wales, said handrails need not be provided beside the bottom two steps except in public buildings and on stairs intended for disabled people; the 2013 English edition does not repeat that, so check with building control first.
Guarding (1.38 to 1.41, Diagram 3.1)
In a dwelling, guard the sides of flights and landings where the drop is more than 600 mm (1.41). For single family dwellings the guarding must be at least 900 mm high on stairs, landings, ramps and edges of internal floors, and 1100 mm on external balconies, including Juliette balconies, and roof edges. Where the building may be used by children under five, no opening may let a 100 mm sphere through and the guarding must not be easy to climb, so avoid horizontal rails (1.39, 3.3).
Open risers (1.9)
Open risers are allowed in dwellings if treads overlap by at least 16 mm and a 100 mm sphere cannot pass through the open riser. With a typical rise, that means a riser bar or upstand in each gap.
Tapered treads and special stairs (1.25 to 1.30)
Measure the going of a tapered tread at the centre on a stair less than 1 m wide, or 270 mm in from each side on a stair 1 m or wider; the narrow end must be at least 50 mm (Diagram 1.9). Consecutive tapered treads have the same going, which may not be less than that of the straight treads (1.26, 1.27). External tapered steps on a dwelling need a going of at least 280 mm (Table 1.1, note 2). Spiral and helical stairs follow BS 5395-2 (1.28); alternating tread stairs are limited to loft conversions serving one habitable room (1.29).
Scotland, Wales and Northern Ireland
Scotland uses the Building (Scotland) Regulations 2004 and the domestic Technical Handbook (April 2026 edition for warrants submitted from 6 April 2026), where stairs fall under Standard 4.3 (Stairs and ramps). Wales publishes its own Approved Document K, currently the 1998 edition incorporating 2000 and 2010 amendments. Northern Ireland uses Technical Booklet H (October 2012) under the Building Regulations (Northern Ireland) 2012.
FAQ
What is the maximum stair rise in the UK?
In England, 220 mm for a private stair in a house (Approved Document K, Table 1.1), provided the pitch stays at 42° or less and 2R + G is between 550 and 700 mm.
What is the minimum going for a domestic staircase?
220 mm, measured nosing to nosing, with a maximum of 300 mm (Table 1.1). At 220 mm, the rise must stay under about 198 mm to respect the 42° pitch.
What is the minimum width of a staircase in a house?
Approved Document K sets none, except 900 mm in the sloping-site case of paragraph 1.16. Where M4(2) applies, Approved Document M asks for 850 mm.
How much headroom does a loft conversion staircase need?
2 m, or, where that is not possible, 1.9 m at the centre of the stair and 1.8 m at the side (1.13, Diagram 1.4).
What height should a stair handrail be?
900 to 1000 mm above the pitch line, on both sides if the stair is 1000 mm wide or more (1.34).
Stair3D gives you a design and a code check to guide your work. Check the measurements on site and with your local building authority before cutting.