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Drawing office notes
Part K stair regulations, worked out in millimetres for metal stairs.
For a stair that serves one house, Approved Document K gives a rise of 150 to 220 mm, a going of 220 to 300 mm and a pitch of 42 degrees or less. Two rises plus one going should total 550 to 700 mm, and the handrail top sits 900 to 1000 mm over the pitch line. Here are the Part K stair regulations as our drawing office uses them: the rule, the reason, then the sums.
Building regulations first, then the guidance
Requirement K1 of the Building Regulations 2010 is the law: stairs that form part of a building must be designed, built and installed so people can move safely between levels. K2 adds barriers wherever they are needed to stop falls.
Approved Document K, 2013 edition, is the government's guidance on meeting both in England. Following it gives a presumption of compliance, not a guarantee, and another solution can be agreed with building control.
Rise, going and pitch: the three numbers that set a stair
Rule. Table 1.1 sorts stairs into three kinds:
| Stair | Rise | Going | Used for |
|---|---|---|---|
| Private | 150–220 mm | 220–300 mm | One dwelling only; 42° pitch at most |
| Utility | 150–190 mm | 250–400 mm | Escape, maintenance, not the daily route |
| General access | 150–170 mm | 250–400 mm | Everyone's day-to-day route |
The rise is tread to tread. The going is nosing to nosing, which is the tread depth less any overlap. The pitch is the angle of a line through the nosings. Treads are level, and every step in a flight has the same rise and going.
Reason. The ranges limit each other. A taller rise needs a deeper going to stay under 42 degrees, and 2R + G stops a tall rise meeting a very deep tread, or a low rise a short one. In an existing building the table still applies unless space makes it impossible, and any alternative is agreed with building control.
Worked example: 2,600 mm floor to floor
The building fixes the floor-to-floor height, so a drawing starts by dividing it into equal risers. These are our own sums on the private-stair limits, not figures printed in the document.
| Risers | Rise | Going that passes | Note |
|---|---|---|---|
| 11 | 236.4 mm | None | Rise over 220 mm |
| 12 | 216.7 mm | 241–266 mm | Pitch and 2R + G both bite |
| 13 | 200.0 mm | 223–300 mm | 240 mm going: 39.8°, 2R + G 640 |
| 14 | 185.7 mm | 220–300 mm | Whole table range |
Thirteen risers give 12 treads, because the upper floor is the last step. At a 240 mm going that is 2,880 mm on plan for a straight staircase, before the landings. If the room is shorter, a multi-flight staircase can turn at a quarter or half landing instead.
Why a 220 mm rise with a 220 mm going fails
Both numbers sit inside the private range, yet 220 over 220 is a 45 degree stair: it passes the table and fails the pitch limit. Keep the 220 mm rise and the going must be 245 to 260 mm. At the shallow end, a 150 mm rise needs a going of 250 mm or more to bring 2R + G up to 550.
Halfway through and want the sums done for your own stair? Ring the drawing office or leave your number below.
Call 07460 042 774Part K stair regulations for handrails and guarding
Handrails. In every building, the rail's top goes 900 to 1000 mm up from the pitch line or floor, and a stair 1000 mm wide or more gets rails on both sides; a narrower one needs a rail on at least one side. The rail may form the top of the guarding where the heights agree. Non-domestic buildings, and shared stairs in flats with no passenger lift, need continuous rails on both sides of flights and landings; in non-domestic buildings the rail also contrasts with its background and follows the profiles in Diagram 1.13.
Guarding height. Guarding can be a wall, a parapet or a balustrade, and Diagram 3.1 gives its minimum heights. In a single-family dwelling, house or flat, guarding beside stairs and landings, and at an internal floor edge, stands at least 900 mm; a roof edge or an outside balcony, Juliet types included, needs at least 1100 mm. Other residential buildings, offices, schools, public buildings and shops keep 900 mm for the flight itself and take 1100 mm at every other edge.
When it is needed. In a dwelling, once the drop beside a flight or landing is more than 600 mm. In other buildings and the shared parts of blocks of flats, from two risers.
The 100 mm sphere. If children younger than five could use the building, size every gap, between spindles, bars or panels, so a 100 mm sphere is stopped and no child can be held fast, and make the guarding hard to climb; the document's advice there is to avoid horizontal rails.
Strength. Guarding has to stand up to the loads that BS EN 1991-1-1 sets, read alongside its UK National Annex and PD 6688-1-1. That is why the fixings appear on our technical drawings, with an engineer's calculation where the inspector needs one.
Headroom, landings and long flights
Headroom. At least 2 m clear: over the flight, taken up from the pitch line; over each landing, taken up from its floor (Diagram 1.3). In a loft conversion where that will not fit, the document accepts 1.9 m at the centre of the stair, falling to 1.8 m at the side.
Landings. Each flight starts and ends on a landing whose width and length both match or beat the flight's narrowest point, kept clear of permanent obstructions. In a house, a door may swing across the bottom landing if 400 mm stays clear.
Long flights. Past 36 risers in consecutive flights, the stair turns at least once, by 30 degrees or more. Caps of 16 risers a flight (utility) or 12 (general access, exceptionally 16 in small premises) apply to non-domestic buildings and the shared stairs in flats, not to a stair inside one house.
Width. Read the document and you will find no general minimum width for a domestic stair. In other buildings it is at least 1200 mm between enclosing walls, strings or upstands, and 1000 mm between handrails.
Open risers, winders and spirals
Open risers. Allowed in a dwelling when the treads overlap by at least 16 mm and a 100 mm sphere cannot pass between them. Other buildings use closed risers, so a toe or a walking aid cannot catch under a tread.
Winders. Consecutive tapered treads share one going, no shorter than the straight treads' going. On a stair under 1 m wide, measure the going at the centre of the tread. On a stair 1 m or wider, check it 270 mm in from each side: the narrow side must not drop below the minimum going and the wide side must not pass the maximum (Diagram 1.9). Keep at least 50 mm of tread at the narrow end.
Spirals and helicals. Both follow BS 5395-2. A spiral turns round a central column, a helical round an open void. Whether a spiral staircase can be the main way up to a room is something we check at the survey.
Who checks a new stair in East Grinstead
East Grinstead is in Mid Sussex district. Mid Sussex District Council's building control advises a full plans application for loft conversions and major structural alterations, and a building notice for smaller or domestic work.
A full plans report normally follows within 15 working days. Building control and planning are two different consents, and one job can need both.
Our drawing office puts every stair on paper at scale, with rise, going, landings and guarding all marked, before fabrication starts, and the drawing is yours to pass to building control. Surveys around East Grinstead are free and normally booked within a week, and we survey across Sussex, Surrey and the Kent border as well. Or send a height and a photo through our quote form.
Questions we are asked about Part K
What does 2R + G mean?
It is two rises added to one going. Table 1.1 treats it as the normal relationship between the two and puts the total between 550 and 700 mm, so a 200 mm rise on a 240 mm going, at 640, passes.
How high should a stair handrail be?
Set its top 900 to 1000 mm over the pitch line, and add a second rail on the other side when the stair reaches 1000 mm wide. LABC's view is that swapping only the handrail in a house generally falls outside building control, apart from a few exceptions, and it recommends the same height. If the balustrade is going too, see our internal balustrade page.
Does a stair in a house need a landing after 16 steps?
No. That cap applies to buildings other than dwellings and to the shared stairs in flats. Every building, a house included, needs a turn of 30 degrees or more once consecutive flights pass 36 risers.
Do I need permission to replace a staircase?
The Planning Portal says a new or replacement stair does not normally need planning permission, though a listed building may need listed building consent. The new stair must still meet Part K, so ask the council's building control team, or another building control body, whether the work needs an application. Our scale drawing of the stair, and an engineer's calculation where the inspector asks for one, can go in with it.
Figures from Approved Document K, 2013 edition (gov.uk) and the Building Regulations 2010, Schedule 1, Part K. Planning and handrail notes from the Planning Portal and LABC; local process from Mid Sussex District Council. We went back to each of these in October 2026.