Staircase Regulations: Rise, Going, Headroom & Balustrade Requirements

Quick Answer: Building Regulations Approved Document K sets the minimum standards for private stairs: maximum rise 220mm, minimum going 220mm, minimum 2m headroom, and balustrade required where a staircase is open-sided with a drop of more than 600mm. Any new staircase or material alteration to an existing one must comply with current Part K requirements.

Summary

Staircase regulations in the UK are defined primarily by Approved Document K (Protection from falling, collision and impact), with additional references to Approved Document M (Accessibility) for certain building types. The regulations distinguish between private stairs (in a single dwelling), common stairs (in multi-unit buildings), and stairs in non-domestic buildings — each with different dimensional requirements.

Getting stairs wrong is one of the most consequential carpentry errors. A staircase that is out of regulation creates a falling hazard, will fail Building Control inspection, and may require complete removal and rebuild. The most common failures are inconsistent rise heights (particularly the first and last riser), inadequate headroom, and balustrading that does not pass the 100mm sphere test.

Material alterations — replacing an existing staircase, significantly altering the pitch, or adding a new staircase to a loft conversion — all require Building Regulations compliance and typically Building Control sign-off. Like-for-like replacement of treads, risers, and balustrades without changing the geometry falls into a grey area but should be discussed with Building Control if there is any doubt.

Key Facts

Quick Reference Table

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Parameter Private Stair Common Stair Note
Max rise 220mm 180mm Per step
Min going 220mm 280mm Measured horizontal
Headroom 2,000mm 2,000mm Minimum at all points
Max pitch 42° 38° Measured to horizontal
Handrail height 900–1,000mm 900–1,000mm From pitch line
Balustrade (stair) 900mm 900mm From pitch line
Balustrade (landing) 900mm 1,100mm From landing level
Sphere gap 100mm max 100mm max Any opening
Min width No minimum 1,200mm Private: good practice 900mm
Rise (mm) Going (mm) Pitch (°) 2R+G (check 550–700)
175 250 34.9° 600 — OK
190 250 37.2° 630 — OK
200 250 38.7° 650 — OK
210 240 41.2° 660 — OK
220 220 45.0° 660 — FAIL (45° exceeds 42° max pitch)
220 240 42.5° 680 — OK (marginal pitch)
175 300 30.3° 650 — OK (comfortable)

Detailed Guidance

Calculating Rise and Going

Before ordering or building a staircase, the floor-to-floor height must be measured precisely. This is the total rise. Divide the total rise by a target riser height to find the number of risers.

Example: Floor to floor = 2,700mm

Critical rule: All risers must be the same height. The tolerance is ±5mm between adjacent risers and ±10mm between any two risers in the flight. Inconsistent risers are the most common cause of trips and staircase failures on inspection.

Headroom Check

Measure headroom from the pitch line (an imaginary line drawn across the nosings of all treads) vertically upward to the soffit or obstruction above. The minimum 2,000mm must be maintained at every point, including at the bottom nosing, at the top nosing, and at any mid-flight obstruction such as a hatch or structural beam.

In loft conversions where geometry is tight, the headroom can reduce to 1,900mm at the bottom of the stair (the area where a person would be standing at the foot) and at the side of the flight where ceiling height reduces — but the main travel path must maintain 2,000mm. Consult Building Control if in doubt.

Balustrade and Handrail

Materials: Any structurally adequate material is acceptable — timber, steel, glass, or composite. The structural requirement is that the balustrade can resist a horizontal load of 0.36 kN/m (approximately 36kg per metre) applied at the top rail — this is a fairly modest load but balusters fixed only with a couple of screws into softwood will not achieve it.

Post fixings: Newel posts must be fixed to structure, not just to the tread. Use a newel bolt (threaded rod through the tread and carriage) or fix the post directly to the trimmer joist. A newel post that rocks is a failing.

Baluster spacing (the 100mm rule): Space balusters at maximum 99mm clear gap. A quick method: cut a 100mm spacer block from offcuts and use it to set each baluster during installation.

Horizontal rails: Approved Document K prohibits balustrade that is "designed to be climbable." Horizontal rails are explicitly flagged as problematic — they act as a ladder for children. Vertical balusters are the safest option.

Glass panels: Where toughened glass panels are used, they must be Grade A safety glass (BS EN 12600 impact classification 1B1 or 1C1). Fix panels in a U-channel or clamp system — never just rely on silicone adhesive.

Winder Stairs

Winder treads (tapered treads at turns) are permitted in private stairs but have additional requirements:

Loft Conversion Stairs

Loft conversion stairs are the most frequently problematic due to space constraints. Key points:

Frequently Asked Questions

Can I build a spiral staircase in a house?

Spiral staircases are generally not acceptable as the primary means of escape from habitable rooms under UK Building Regulations, as they cannot achieve the 2m headroom requirement and the going dimension at the walking line is typically too narrow. They may be acceptable as a secondary stair or for access to a non-habitable space (e.g. a small mezzanine study), but this should be agreed with Building Control before work starts.

Does replacing an existing staircase require Building Regulations approval?

It depends. A like-for-like replacement of treads, risers, or balusters (same geometry, same dimensions) is maintenance and does not require approval. If you are altering the rise, going, or geometry, or if the existing staircase serves a room created by a conversion, Building Regulations approval is required. Always check with Building Control if unsure.

What is the rule about handrails on both sides?

Part K requires a handrail on at least one side of a private stair. If the stair is wider than 1,000mm, a handrail is required on both sides. For stairs with an open side (no wall), a full balustrade must be provided on that side. Handrails must be continuous and graspable — a flat top rail on a balustrade is not an acceptable handrail unless it meets the graspability requirements (typically 45–50mm diameter circular or oval section preferred).

What is "pitch line" and why does it matter?

The pitch line is an imaginary straight line drawn across the nosings (front edges) of all treads. Headroom and handrail height are measured from this line rather than from the tread surface itself, because the pitch line represents the travel path. A handrail that starts at 900mm above the first tread surface will be shorter at the top of the flight if it does not follow the pitch line consistently — this is a common error that leads to non-compliance.

My customer wants an open-tread staircase — is that allowed?

Open treads (no risers) are permitted for private stairs, but any gap between treads must not allow a 100mm sphere to pass through. This means the gap cannot exceed 99mm. With a standard going of 250mm, the vertical gap from the underside of one tread to the top of the tread below will typically be less than 100mm, but always check the actual dimension for the specific design.

Regulations & Standards