What are the stair rules in Approved Document K?
Published · Updated · By Sai Nath
For a private stair in England, Approved Document K (2013 edition, Table 1.1) allows a rise of 150 to 220 mm and a going of 220 to 300 mm, with twice the rise plus the going between 550 and 700 mm and a pitch of 42° at most. Headroom is 2.0 m and guarding 900 mm.
What are the Part K limits for a private stair?
Approved Document K is the government's guidance on Part K of the Building Regulations 2010 in England. Its 2013 edition, in force since 6 April 2013, is still current: on 1 November 2026 gov.uk lists no newer edition or amendment. A private stair serves one dwelling, every step in a flight has the same rise and going (paragraph 1.5), and all of these apply at once:
| Rule | Limit | Where |
|---|---|---|
| Rise | 150 to 220 mm | Table 1.1 |
| Going, nosing to nosing | 220 to 300 mm | Table 1.1, Diagram 1.1 |
| 2R + G (twice the rise plus the going) | 550 to 700 mm | Table 1.1, note |
| Pitch | 42° at most | Table 1.1, note 1 |
| Headroom | 2.0 m above the pitch line and landings | 1.11, Diagram 1.3 |
| Handrail height | 900 to 1000 mm above the pitch line or floor | 1.34 |
| Guarding | where the drop is over 600 mm; 900 mm high on stairs and landings | 1.41, 1.38, Diagram 3.1 |
| Openings in guarding and open risers | a 100 mm sphere must not pass | 1.39, 1.9 |
The pitch is the angle of the line through the nosings (Appendix A): pitch = arctan(rise ÷ going). So the 220 mm maximum rise and 220 mm minimum going can't be used together, because arctan(220 ÷ 220) = 45°. With tan 42° = 0.9004, a 220 mm rise needs a going of at least 220 ÷ 0.9004 = 244.3 mm. Utility and general access stairs, used in other buildings, have their own tighter rows in Table 1.1.
Worked example: a 2600 mm floor-to-floor stair
A two-storey house with 2600 mm from finished floor to finished floor, and the shortest straight flight Approved Document K allows.
- Fewest risers: 2600 ÷ 220 = 11.8, so 12 risers. Eleven would be 2600 ÷ 11 = 236.4 mm, over 220.
- Rise: 2600 ÷ 12 = 216.67 mm. ✓ Inside 150 to 220.
- Going for 42°: at least 216.67 ÷ 0.9004 = 240.6 mm. Take 245 mm. ✓ Inside 220 to 300.
- 2R + G: 2 × 216.67 + 245 = 678.3 mm. ✓ Inside 550 to 700.
- Pitch: arctan(216.67 ÷ 245) = 41.5°. ✓ Under 42°.
- Floor length: 12 − 1 = 11 treads, so 11 × 245 = 2695 mm of going.
- Headroom: 2.0 m above the pitch line. With a 200 mm floor zone (an example), the opening above is (200 + 2000) × 245 ÷ 216.67 = 2487.7 mm long.
More risers give a gentler stair if there is room. Each of these passes:
| Risers | Rise | Going | 2R + G | Pitch | Length of going |
|---|---|---|---|---|---|
| 12 | 216.7 mm | 245 mm | 678.3 mm | 41.5° | 2695 mm |
| 13 | 200.0 mm | 225 mm | 625.0 mm | 41.6° | 2700 mm |
| 14 | 185.7 mm | 220 mm | 591.4 mm | 40.2° | 2860 mm |
| 14 | 185.7 mm | 250 mm | 621.4 mm | 36.6° | 3250 mm |
Twelve and thirteen risers take almost the same floor, because the 42° cap sets the going in both; thirteen 200 mm risers on 220 mm goings fail at arctan(200 ÷ 220) = 42.3°. Measure between finished floor levels: paragraph 1.5 wants a consistent rise but gives no tolerance, so ask building control. More on the 2R + G formula and stairwell openings.
How do I work it out in MeisterCalc?
Use the free Stairs calculator. Its amber warnings use Australian NCC figures (such as a riser over 190 mm or under 115 mm), so a UK riser of 190 to 220 mm can show a warning that doesn't apply in England. To cap risers at England's 220 mm, open Advanced, tick Riser Limited and set Desired Riser Height to 220: the app then rounds the riser count up, so no riser is taller than 220 mm.
For the example: Home ▸ Stairs ▸ Rise Only, Total Rise 2600 mm, Going 245 mm, Riser Limited ticked and Desired Riser Height 220 mm, leaving Floor / Joist Thickness 200 mm and Headroom Height 2000 mm. It shows Number of Risers 12, Actual Riser Height 216.7 mm, Number of Treads 11, Stairwell Opening 2487.7 mm and Incline Angle 41.49°. Its Total Run, 2940.0 mm, counts one going per riser, so the angle equals the pitch here; in Rise + Run, check the pitch as arctan(rise ÷ going). It doesn't check the 42° limit, handrails or guarding, or do winders and landings.
What about loft conversions?
- Headroom: where 2.0 m won't fit, 1.9 m at the centre of the stair's width, falling to 1.8 m at the side (1.13, Diagram 1.4).
- Alternating tread stairs: only where a normal stair won't fit, to one habitable room plus, if wanted, a bathroom or WC that isn't the only WC (1.29). Rise at most 220 mm, going at least 220 mm between alternate nosings, handrails both sides, 2 m headroom (1.30, Diagram 1.10).
- Fixed ladder: only to one habitable room, with handrails both sides (1.32). A retractable ladder can't be a means of escape (1.31, Approved Document B).
How wide must a stair be?
Approved Document K sets no minimum width for a private stair. Its one width for houses is 900 mm, for steps inside the entrance storey on a severely sloping plot (1.16). Where planning conditions make the home M4(2) or M4(3), Approved Document M, Volume 1 asks for 850 mm clear on the stair from the entrance storey, measured 450 mm above the pitch line, ignoring the newel (2.23, 3.30).
What are the rules for handrails and guarding?
- Handrails: both sides on a stair 1000 mm or wider (1.34). The 2013 edition is silent on narrower stairs and the bottom steps (the Welsh 1998 edition asks for one side below 1 m and lets most homes skip the bottom two), so ask building control. A handrail can be the top of the guarding if the heights match.
- Guarding height: 900 mm on stairs, landings and internal floor edges in a house; 1100 mm on external balconies, Juliette balconies and roof edges (Diagram 3.1).
- Gaps and climbing: no opening a 100 mm sphere can pass, and hard for small children to climb (1.39, 3.3). The spindle sums are in the maximum gap between stair spindles in the UK.
- Open risers: treads overlap at least 16 mm (1.9). With 216.7 mm risers and 38 mm treads (an example) the gap is 216.7 − 38 = 178.7 mm, so it needs a riser board or bar.
What about landings, winders and long flights?
- Landings: top and bottom of every flight, at least as wide and long as the flight's narrowest width; part of the floor can count (1.20, 1.21). A door may swing across the bottom landing if it leaves 400 mm clear (1.24).
- Winders: measure the going at the centre of a stair under 1 m wide, or 270 mm in from each side of a wider one; at least 50 mm at the narrow end, and no less than the straight treads' going (1.25 to 1.27, Diagram 1.9).
- Long flights: no riser limit per flight for a private stair, but more than 36 risers in consecutive flights need a change of direction (1.17).
- Existing buildings: where Table 1.1 can't fit, agree an alternative with building control.
Do Wales, Scotland and Northern Ireland use the same figures?
No. Each publishes its own guidance:
| Figure | England | Wales | Scotland | Northern Ireland |
|---|---|---|---|---|
| Rise | 150 to 220 mm | 220 mm at most | 100 to 220 mm | 75 to 220 mm |
| Going | 220 to 300 mm | 220 mm at least | 225 mm at least | 220 mm at least |
| Minimum width | none set | none set | 900 mm (800 mm with two handrails) | 800 mm (600 mm in some cases) |
| Rises in a flight | not set | not set | 16 at most | 2 to 16 |
| Handrail height | 900 to 1000 mm | 900 to 1000 mm | 840 to 1000 mm | 900 to 1000 mm |
| Guarding on the flight | 900 mm | 900 mm | 840 mm | 900 mm |
All four use a 42° pitch, 2R + G of 550 to 700 mm and 2.0 m headroom. Wales uses its 1998 edition of Approved Document K, Scotland the April 2026 domestic Technical Handbook and Northern Ireland Technical Booklet H (October 2012); tables and clauses are under Sources.
Is Approved Document K changing?
Not yet. The Building Safety Regulator's call for evidence on Part K runs from 19 October to 28 December 2026. It proposes no changes, the current guidance stays in place, and any change would be consulted on first.
Before you build
Following Approved Document K gives a presumption that the work meets Part K, and building control can accept another way. Your building control body decides what applies to your stair, not this page or the app: see how building control works in the UK.
Sources
Checked on 1 November 2026. These pages explain the rules; the code itself, your plans and your council, building consent authority, building control body or certifier decide what a job needs.
- Approved Document K: protection from falling, collision and impact, 2013 edition (PDF): For use in England, in force since 6 April 2013: Table 1.1 and its notes; paragraphs 1.5, 1.9, 1.11, 1.13, 1.16, 1.17, 1.20, 1.21, 1.24 to 1.32, 1.34, 1.38, 1.39, 1.41 and 3.3; Diagrams 1.1, 1.3, 1.4, 1.9, 1.10 and 3.1; Appendix A. (checked 1 November 2026)
- Approved Document K on GOV.UK: Lists the 2013 edition as the current document; no later edition or amendment. (checked 1 November 2026)
- Building Safety Regulator: call for evidence on Part K: Opened 19 October 2026, closes 28 December 2026; proposes no changes and the current guidance stays in place. (checked 1 November 2026)
- Approved Document M, Volume 1: dwellings (PDF): 2015 edition incorporating 2016 amendments: paragraphs 2.23 and 3.30, 850 mm stair width in M4(2) and M4(3) homes. (checked 1 November 2026)
- Approved Document K for Wales (Welsh Government): 1998 edition incorporating 2000 and 2010 amendments, for use in Wales (page updated 19 March 2025): Table 1 and its note; paragraphs 1.5, 1.10, 1.11, 1.13, 1.14 and 1.27; Diagram 11. (checked 1 November 2026)
- Building standards technical handbook: domestic, April 2026 (Scottish Government): For building warrants submitted from 6 April 2026: Tables 4.3, 4.5 and 4.7; clauses 4.3.4, 4.3.15 and 4.3.16. (checked 1 November 2026)
- Technical Booklet H: stairs, ramps, guarding and protection from impact (Department of Finance, Northern Ireland): October 2012: Tables 3.1, 3.2 and 5.1; paragraphs 3.5, 3.9, 3.12, 3.16 and 3.27. (checked 1 November 2026)
Do the maths in MeisterCalc
MeisterCalc does the arithmetic behind these rules on an Android phone, with no signal needed: Stairs, Concrete and Check Square are free, and the other calculators come with Pro. It runs on Android 7.0 or later.