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

The requirement

For a private stair in a home in England, Approved Document K sets the numbers. Each step can rise no less than 150 mm and no more than 220 mm. The going must be 220 to 300 mm deep. The whole flight must not be steeper than 42°. Guarding on stairs and landings is 900 mm high.

Two words do the work here. The rise is how tall each step is. The going is how deep it is. Measure the going from the front edge of one step to the front edge of the next.

Make every step in the flight the same rise and the same going. One odd step is where people trip. An external stair to a home needs a deeper going of 280 mm or more.

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). A loft conversion gets one break where you cannot get the full height. There the headroom can drop to 1.9 m at the side of the stair and 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 pitch line runs across the front edges of the steps. If the flight is 1000 mm wide or more, put a handrail on both sides.

Width is different. Approved Document K sets no minimum width for a normal private stair. Practical guidance in BS 5395 points to around 800–900 mm. Treat that as guidance, not a Doc K rule. The code leaves width 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. You need it wherever the drop is more than 600 mm. On stairs, landings and internal floor edges it must be 900 mm high. On external balconies and roof edges it must be 1100 mm high.

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

Check the gaps too. A 100 mm sphere must not pass through any gap in the guarding. Then think about small children. Where children under 5 may use the stair, the guarding must not be easy to climb. That includes homes. 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. 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. That is right on the limit. Add one riser to ease it off: 2640 ÷ 13 = 203 mm per step. Better.
Pick a going. Try 250 mm. That sits inside the 220–300 range.
Check the pitch. A 203 mm rise over a 250 mm going is well under the 42° limit. The flight is fine.

Not happy with the rise? Change the riser count or the going. Keep the rise under 220 mm and the pitch under 42°. The calculator does this in one go.

Do it in 5 seconds

UK building regulations: rules by nation explains how the code works across England, Wales, Scotland and Northern Ireland.
NCC stairs for chippies (Australia) covers 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 is how deep the step is, front edge to front edge. For a private stair it must be at least 220 mm, 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. 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. Northern Ireland uses Technical Booklet H. They are separate documents with their own numbers. Always check which nation the job is in.