At a glance
| Item | Approved Document K, 2013 (England) | Para | What to write or check |
|---|---|---|---|
| Rise and going | Table 1.1. Private stair: rise 150 to 220 mm, going 220 to 300 mm, pitch 42° at most. Utility: 150 to 190, 250 to 400. General access: 150 to 170, 250 to 400. | 1.3 | Survey the floor-to-floor height, then set out. |
| Open risers | Dwellings: allowed if treads overlap 16 mm or more and a 100 mm sphere cannot pass. Other buildings and common stairs in flats: risers not open. | 1.6, 1.9, 1.10 | Show overlap and sphere check, or closed risers. |
| Nosings | Other buildings: contrasting, 55 mm wide or more on tread and riser; any protrusion 25 mm or less. Common stairs in flats: 50 to 65 mm tread, 30 to 55 mm riser. | 1.7, 1.10 | Contrasting nosing strip or edge. |
| Handrails | Top 900 to 1,000 mm from the pitch line; both sides if the stair is 1,000 mm or wider. Slip-resistant surface that does not get excessively hot or cold. | 1.34, 1.36 | Height from the pitch line; name metal and finish. |
| Guarding and infill | Other buildings: at two or more risers. Dwellings: at a drop over 600 mm. Height per Diagram 3.1. Where under-fives may be present: 100 mm sphere cannot pass, not readily climbed. | 1.38 to 1.41, 3.3 | Sphere check on baluster gaps. See the balustrade sheet. |
| Spiral, helical, industrial | Spiral and helical: BS 5395-2. Industrial stairs: BS 5395-3 or BS 4211 (ladders). | 1.28, 1.33 | Ask the engineer and Building Control. |
| Loads on guarding | BS EN 1991-1-1 with its UK National Annex and PD 6688-1-1; BS 6180 for barriers. No load is quoted here. | 3.2c | The engineer states the load case. |
Measured in millimetres. The paragraph numbers are those of the 2013 edition. Table 1.1 and the other dimensions are quoted as printed.
Six checks on a metal stair
The drawing numbers six places where a metal stair is most often questioned. The first is the nosing: other than in dwellings, Approved Document K asks for a visually contrasting nosing, at least 55 mm wide on both tread and riser. The second and third are the 100 mm sphere. In a dwelling, open risers are allowed only if the treads overlap by at least 16 mm and a 100 mm diameter sphere cannot pass through the opening. In a building other than a dwelling, and in the common stairs of flats, the risers should not be open at all. The same size of sphere is applied again to the balustrade where under-fives may be present. The fourth is the handrail, 900 to 1,000 mm from the pitch line. The fifth is the structure, which the Approved Document leaves to a loads standard and the engineer. The sixth is the guarding at the edge, whose height depends on the building type. One more point suits floating stairs: if the soffit is less than 2 m above the floor, the area beneath needs guarding and low-level cane detection, or a barrier giving the same protection (para 1.8).
The rise and going come first, because nothing else sets out until they are fixed. Table 1.1 gives the three categories as printed.
| Stair category | Rise, min to max (mm) | Going, min to max (mm) | Notes |
|---|---|---|---|
| Private stair | 150 to 220 | 220 to 300 | Maximum pitch 42°. For dwellings, external tapered steps part of the building: going at least 280 mm. |
| Utility stair | 150 to 190 | 250 to 400 | |
| General access stair | 150 to 170 | 250 to 400 | In schools the preferred going is 280 mm and rise 150 mm. |
The document describes twice the rise plus the going as falling normally between 550 and 700 mm. It reads as the usual relationship, not a stated limit. Headroom, width and landings are in our stair rise, going and headroom sheet, and the guarding table is in balustrade and handrail rules. Parts of a stair are named in staircase anatomy and terminology.
Which rule applies to which stair
The same stair detail can be right in one building and wrong in the next. Approved Document K sorts stairs into dwelling, other building, common area of flats, spiral or helical, and industrial or maintenance. Decide the category first and write it on the drawing. The document does not say which row of Table 1.1 a common stair in a block of flats should follow, so ask Building Control. For spiral and helical stairs it points to BS 5395-2 and does not repeat the Table 1.1 figures in that paragraph; whether and how they apply is for Building Control and the engineer.
A stair that forms part of a means of escape is also governed by Approved Document B (paragraph 1.14 points there). That is a fire-engineering question and is not covered here.
Treads, nosings and slip
Metal treads come as plate, folded plate, perforated or open grid, or as a carrier for timber, stone or glass. Approved Document K sets the nosing contrast, the overlap limits and the sphere. It gives no slip value for a stair tread. It asks for slip-resistant surfaces on the treads of alternating tread stairs and on handrails, and for ramps, but does not give a number. Slip on a stair tread is therefore a specification item of its own: ask for a test report on the actual tread surface, wet and dry. Our slip resistance sheet explains the pendulum test and why no single target value exists.
- Open-grid or perforated treads. Approved Document K does not address the openings in a tread as such. Ask Building Control how the 100 mm sphere and foot-trap concerns apply, and say which tread you mean on the drawing.
- Coated treads. A powder coat or paint wears at the nosing first, which is where contrast and slip matter. Ask for the coating system and the wear detail.
- Treads on a tapered or winding stair. Measure the going as the document shows, and ask the engineer about the narrow end.
Structure: the part only an engineer settles
Approved Document K sets no deflection or fixing rule for a stair. For guarding it points to BS EN 1991-1-1 with its UK National Annex and PD 6688-1-1, and to BS 6180 for barriers. For stair structure the figures come from the engineer, not from this sheet. The brief to the engineer and the partner fabricator should cover the following.
- Who designs the stringer, the tread supports and the connection to the building, and when the calculation is issued: before shop drawings, not after.
- The fixing to the structure. Anchors into concrete or masonry and welded or bolted connections are an engineer’s call. See fixings and fasteners for metalwork.
- Feel, not just strength. A floating or cantilevered stair can be strong and still bounce. The limit is for the engineer to state and the client to accept.
- Survey and tolerance. A stair is made to site measurement. Allow for the survey in the programme; see site survey and dimension verification and tolerances for visible metalwork.
- Welds, finish and corrosion. Visible welds, galvanising or powder coat, and any dissimilar metals are covered in weld finish, hot-dip galvanising and galvanic corrosion.
- Execution standard. Ask the partner fabricator which execution standard and class the structural steelwork is built to, and for the declaration documents. The standard itself was not read for this sheet.
Before the drawing goes to Building Control
- Stair category written on the drawing, and the building it serves.
- Finished floor heights surveyed, risers counted, rise and going within Table 1.1.
- Open risers: overlap and the 100 mm sphere check shown; or closed risers.
- Nosing contrast and width; tread surface and its slip evidence.
- Handrail height from the pitch line, both sides if 1,000 mm or wider, finish and continuity at landings.
- Guarding height and infill, with the 100 mm sphere check where under-fives may be present.
- Space under the stair protected if the soffit is below 2 m.
- Engineer’s load statement and calculation, and who is responsible for the fixings.
- Fire strategy if the stair is on an escape route (Approved Document B).
Approved Document K is 2013 edition and the gov.uk page shows no later issue. A gov.uk call for evidence on Part K was announced in October 2026, and the sources we saw say existing requirements remain in force meanwhile. Check the current position before each submission.
Specification wording
Paste into your schedule or specification and replace anything in [square brackets] with your own figures. Wording is a starting point: your specification governs.
Stair [S1] is a [private stair in a dwelling / stair in a building other than a dwelling / common stair in a block of flats] and is to comply with Approved Document K (2013 edition, England). Rise [ ] mm (Table 1.1 range for the category) and going [ ] mm, constant throughout each flight, maximum pitch [42°] for a private stair. Finished floor-to-floor height [ ] mm to be verified on site before shop drawings.
[Dwelling: open risers. Treads overlap by not less than [16] mm and no opening allows a 100 mm diameter sphere to pass.] [Other buildings and common stairs in flats: risers closed.] The sphere check is to be shown on the shop drawing.
Tread nosings to contrast visually with the tread and riser, [55] mm wide on tread and riser, protruding no more than [25] mm. Tread surface [finish] to be supported by a slip-resistance test report for the surface and finish as supplied, wet and dry, to [method and edition to be stated by the specifier].
Handrail [diameter and metal] with its top [900 to 1,000] mm above the pitch line, on [both sides / one side], continuous at landings, with a [finish] that is slip-resistant and contrasts with its background. Guarding [900] mm on flights and [1,100] mm on landings, infill such that a 100 mm sphere cannot pass and it cannot readily be climbed. Loads per [standards confirmed by the engineer].
Stringers, tread supports, fixings and connections to be designed by [name], chartered structural engineer, with calculations issued before fabrication. Fixing method, anchor type and deflection limit to be stated by the engineer. Substitution of section, material or fixing requires written approval.
Terms used on this page
- Rise
- The vertical distance between the top surfaces of successive treads.
- Pitch line
- The sloping line connecting the nosings of a flight. Handrail height is measured from it.
- Nosing
- The front edge of a tread. Approved Document K asks for it to contrast visually in most buildings.
- Open riser
- A step with a gap between treads instead of a closed riser. Allowed in dwellings only, with limits.
Standards and sources
- Approved Document K: Protection from falling, collision and impact, 2013 edition, for use in England: gov.uk page shows publication 3 January 2013; text read 7 Nov 2026.
- gov.uk: Have your say on the future of Part K: call for evidence, Oct 2026; search results only.
- BS 5395-2 (helical and spiral stairs), BS 5395-3 (industrial stairs), BS 4211 (ladders): cited by ADK; not read; BS 5395-2 shown under revision: confirm.
- BS 5395-1:2010 (straight stairs and winders): listed current; not read; not cited by ADK 2013.
- BS EN 1991-1-1 with UK National Annex, PD 6688-1-1, BS 6180:2011: cited by para 3.2; not read.
Questions we are asked
Can a steel staircase have open risers?
In a dwelling, yes, if the treads overlap by at least 16 mm and a 100 mm diameter sphere cannot pass through the openings (Approved Document K, 2013, para 1.9). In a building other than a dwelling, and in the common stairs of flats, the risers should not be open (paras 1.6 and 1.10).
What is the handrail height on a stair?
The top of the handrail is 900 to 1,000 mm from the pitch line or floor (para 1.34a). A stair 1,000 mm or wider needs a handrail on both sides (para 1.34c). Guarding heights are in Diagram 3.1.
Does Approved Document K give a slip value for stair treads?
No. It asks for slip-resistant surfaces on handrails, ramps and alternating tread stairs but gives no number for a stair tread. Ask for a test report on the tread surface and finish, and see our slip resistance sheet.
Do spiral stairs have to meet Table 1.1?
The document says to design spiral and helical stairs in accordance with BS 5395-2 (para 1.28). We have not read that standard and the paragraph does not restate Table 1.1, so ask Building Control and your engineer.
Who designs the structure of a metal stair?
A chartered structural engineer. Approved Document K sets no deflection or fixing figure and points to loads standards for guarding. The studio coordinates manufacture through partner workshops; the engineering responsibility should be named in the contract.
Is Approved Document K about to change?
A call for evidence on Part K was announced in October 2026. The sources we saw say it proposes no policy change and current requirements remain. The 2013 edition is the one on the gov.uk page; check before each submission.
Download the factsheet
A two-page A4 PDF with the Approved Document K checks table, the six-checks drawing and paste-in specification wording for a metal stair, to keep with your project file.