UK Stair Rules (Approved Document K): Rise, Going, Guarding

The requirement

A stair has to be steep enough to fit the space, but shallow enough to climb safely. For a private stair in a home, Approved Document K sets this with two numbers you set out on site — the rise and the going — plus a limit on how steep the whole flight can be.

Rise — how tall each step is.
Going — how deep each step is, measured from the front edge of one step to the front edge of the next.

Each step must rise no more than 220 mm and no less than 150 mm. The going must be at least 220 mm, up to 300 mm. An external stair to a home needs a going of 280 mm or more. Whatever rise and going you pick, the flight must not be steeper than a pitch of 42°. Every step in the flight should be the same rise and the same going — one odd step is where people trip.

Dimension	Limit (Approved Document K, England)
Rise	max 220 mm · min 150 mm
Going	max 300 mm · min 220 mm (external ≥ 280 mm)
Pitch	max 42°
Headroom	min 2000 mm (2 m)
Handrail height	900–1000 mm above the pitch line
Width	not set by Doc K for a private stair — see below

Headroom over the whole stair must be at least 2000 mm (2 m). There is one concession for a loft conversion where you cannot get the full height: 1.9 m at the side of the stair, dropping to 1.8 m at the centre.

You need a handrail where there is a drop. Fit it 900–1000 mm above the pitch line (the line that runs across the front edges of the steps). If the flight is 1000 mm wide or more, put a handrail on both sides.

On width, Approved Document K does not set a minimum for an ordinary private stair. Practical guidance (BS 5395) points to around 800–900 mm, but treat that as guidance, not a Doc K requirement — the code leaves it open.

Approved Document K · Table 1.1 (England)

Guards & barriers

Guarding is the barrier that stops a fall from the edge of a stair, landing or floor. Approved Document K sets when you need it and how high it goes.

Where	Guarding height (Approved Document K, England)
Stairs, landings and ramps	900 mm
Internal floor edges	900 mm
External balconies and roof edges	1100 mm

You need guarding wherever the drop is more than 600 mm. For the gaps in the guarding: a 100 mm sphere must not be able to pass through. And where children under 5 may use the stair — which includes homes — the guarding must not be easy to climb, so avoid horizontal rails or footholds a child could use as a ladder.

Work it out on site

Say your floor-to-floor height is 2640 mm and you want an even set of steps.

Pick how many risers. 2640 ÷ 220 (the tallest a rise can be) = 12. So you need at least 12 risers. 2640 ÷ 12 = 220 mm per step — right on the limit. Add one to be comfortable: 2640 ÷ 13 = 203 mm per step. Better.
Pick a going. Try 250 mm — inside the 220–300 range.
Check the pitch. A 203 mm rise over a 250 mm going is well under the 42° limit, so the flight is fine.

Change the number of risers or the going until the rise sits comfortably under 220 mm and the pitch stays under 42°. The calculator does this in one go.

Do it in 5 seconds

UK building regulations: rules by nation — how the code works across England, Wales, Scotland and Northern Ireland.
NCC stairs for chippies (Australia) — the same job under Australian rules, if you build in both places.

Sources

Approved Document K, Protection from falling, collision and impact (2013 edition, England), Table 1.1 — rise, going, pitch, headroom, handrail and guarding for a private stair. Read it at gov.uk. (Confirmed against Approved Document K, verified 2026-07-28.)
Adoption / edition caveat: these are England’s figures from Approved Document K (2013). Building rules in the UK are devolved. Wales runs a parallel Approved Document K that currently matches, but can change. Scotland uses the Building Standards Technical Handbook and Northern Ireland uses Technical Booklet H — separate documents with their own numbers, not shown here. Doc K is guidance showing one way to meet the Building Regulations; check the current edition and confirm which nation the job is in before you rely on any figure.

State variations

These states apply requirements that differ from the national provisions for this rule.

Scotland Adopted Approved Document K

Current code: Technical Handbook - Domestic (April 2026)

Scotland's Technical Handbook requires a deeper going (225 mm) and allows lower handrails and in-dwelling stair guarding (840 mm) than England's Doc K.

Scotland building codes → Official source → Verified 2026-07-28

Frequently asked questions

What is the maximum rise for stairs in England?

For a private stair in a home, Approved Document K says each step can rise no more than 220 mm, and no less than 150 mm. Every step in the flight should be the same rise. This is the England figure — Scotland and Northern Ireland use their own documents with their own numbers.

What is the minimum going for a stair?

The going — how deep the step is, front edge to front edge — must be at least 220 mm for a private stair, up to 300 mm. An external stair to a home needs a going of 280 mm or more. These are the Approved Document K figures for England.

How steep can a private stair be?

Approved Document K limits a private stair to a pitch of 42 degrees. If your rise and going are inside their ranges the pitch usually looks after itself, but a steep stair can still tip over 42° — worth a quick check.

When do I need guarding on a stair or landing?

Guarding is required wherever the drop is more than 600 mm. On stairs, landings and internal floor edges the guarding is 900 mm high. On external balconies and roof edges it is 1100 mm. A 100 mm sphere must not pass through any gap, and it must not be easy for a small child to climb.

Do the same rules apply across the whole UK?

No. Building rules are devolved. Approved Document K covers England, and Wales runs a parallel document that currently matches. Scotland uses the Building Standards Technical Handbook and Northern Ireland uses Technical Booklet H — separate documents with their own numbers. Always check which nation the job is in.