UK Staircase Building Regulations 2026 – Complete Guide to Part K

Rise & Going – Step Dimensions

The rise is the vertical height of each step, and the going is the horizontal depth of each tread. Together, they determine how comfortable and safe a staircase is to use. Part K specifies minimum and maximum values for both, depending on the type of staircase.

Private Domestic Stairs

Rise & Going by Staircase Type

Open Riser Steps – Nosing Overlap

For staircases with open risers (no vertical panel between treads), each tread must overlap the one below by a minimum of 16mm. This nosing overlap reduces the gap between treads and helps prevent feet or walking aids from slipping through. See the Open Riser section for full requirements.

Staircase Pitch & Steepness

The pitch of a staircase is the angle it makes with the horizontal. A steeper staircase is harder and more dangerous to climb, particularly for elderly users, children and people with mobility difficulties. Part K sets a maximum pitch for each staircase type.

How to Calculate Staircase Pitch

The pitch angle is calculated using the rise and going: tan(pitch) = Rise ÷ Going. For example, a staircase with a 220mm rise and 250mm going has a pitch of arctan(220/250) = approximately 41.3° — just within the 42° maximum for private stairs.

Maximum Number of Risers Per Flight

Part K states that a staircase must not have more than 36 risers in a consecutive flight without a change of direction. If your staircase requires more than 36 steps, you must introduce at least one landing to break the flight. This applies to all staircase types.

Staircase Headroom Regulations UK

Adequate headroom ensures users can move up and down a staircase without risk of striking their head on a ceiling, beam or floor above. Part K specifies a minimum headroom that must be maintained throughout the entire length of the staircase — including landings.

Headroom on Sloping Ceilings

Where a staircase is positioned beneath a sloping ceiling — for example, under the slope of a roof — the 2000mm headroom must still be maintained throughout. This often requires careful positioning of the staircase, adjusting the pitch angle, or altering the ceiling design to ensure compliance.

Loft Conversion Exception

For loft conversions where there is insufficient space to achieve the standard 2000mm headroom, Part K permits a reduced headroom — provided the staircase is the only practicable option and the conversion is into a loft that was not previously used as habitable space. In these cases:

• Minimum 1800mm at the lowest point (low-ceiling side of the stair width)
• Minimum 1900mm at the centre of the stair width

This exception applies only to loft conversions — it cannot be used to justify reduced headroom on a standard staircase. Always confirm the exception applies with your local Building Control authority before designing the staircase. See the full Loft Conversion section for alternating tread stair requirements.

Staircase Width & Landing Regulations

Staircase Width

For private residential staircases, Part K does not specify a minimum width. In practice, 850mm is widely regarded as the minimum comfortable width for a domestic staircase — narrow enough to fit in most homes, wide enough for comfortable single-file use and the movement of furniture.

Landing Regulations

Landings are required at the top and bottom of every flight of stairs. They provide a rest point, space to change direction, and a safe area for door swings. Part K specifies the following requirements for landings:

• Width: Must be at least as wide as the narrowest part of the staircase it serves
• Depth: Must be at least as deep as the width of the narrowest part of the staircase
• Level surface: All landings must be level — no slope or gradient
• Clear of obstructions: Landings must be free from permanent obstructions
• Maximum risers per flight: No more than 36 risers without a landing

Doors Opening onto Landings

Where a door opens onto a landing at the top or bottom of a staircase, there must be sufficient space for the door to open without the user being forced onto the first or last step. The door swing must leave a clear space of at least 400mm between the door and the edge of the staircase. Doors must never swing over steps.

Handrail Regulations UK – Part K

Handrails are a mandatory safety requirement on all staircases in the UK. Part K specifies requirements for handrail height, positioning, continuity and strength. Getting handrails right is not just about compliance — a well-positioned, continuous handrail significantly reduces the risk of falls, particularly for elderly users and children.

Handrail Height Requirements

When Are Handrails Required?

Handrail Continuity & Grip

Handrails should be continuous for the full length of the staircase — from the bottom step to the top step, without interruption. They must be graspable: a circular section handrail should have a diameter of 32–50mm, providing a comfortable grip for most users.

Handrails must be securely fixed and capable of withstanding the horizontal loads imposed by users. They should be set away from any wall by a minimum of 50–75mm to allow the hand to travel along the full length without obstruction.

Handrail Exemptions – Short Flights

Part K does not require a handrail where a flight has fewer than two risers. A single step at the entrance to a property, for example, does not legally require a handrail — although one is always recommended for safety.

Balustrade & Guarding Regulations UK

Where a staircase or landing has an open edge — a drop of 600mm or more — a balustrade or guarding must be provided. Part K (K2) sets out the minimum height, structural performance and opening size requirements for balustrades on staircases and landings.

Minimum Balustrade Height

The 100mm Sphere Rule

Any opening in a balustrade — between spindles, glass panels, horizontal rails or any other element — must be small enough that a 100mm diameter sphere cannot pass through. This rule exists to prevent young children from getting their head trapped between balustrade elements.

Climbability – Horizontal Rails

Part K specifically warns against balustrade designs that are easy for children to climb. To reduce climbability risk, horizontal rails between 150mm and 875mm from the floor or pitch line should be avoided. This means traditional ranch-style horizontal bar balustrades are not recommended for domestic properties with young children, as they act as a ladder.

This is why vertical bar and glass panel balustrades have become the dominant choice for modern staircases — they offer no horizontal footholds within the climbable zone.

Structural Performance

Balustrades must be structurally capable of withstanding the loads imposed by users. Under BS 6180:2011, the minimum horizontal imposed load for a domestic balustrade is 0.74 kN/m. For commercial and public balustrades the requirement is higher — typically 3.0 kN/m. All Continox glass balustrades are designed and tested to meet or exceed these requirements.

Open Riser Staircase Regulations UK

Open riser staircases — where there is no vertical panel (riser) between treads — are permitted in domestic properties under Part K, provided specific safety requirements are met. They are one of the defining features of modern bespoke staircases, creating a light, open feel that allows natural light to pass through the staircase.

Key Requirements for Open Risers

The 100mm sphere rule for open risers is the same principle as for balustrade openings — the gap between treads must be small enough that a 100mm sphere (approximately the size of a young child's head) cannot pass through. This prevents children from slipping through or becoming trapped between steps.

The 16mm nosing overlap means that each tread must project horizontally over the tread below by at least 16mm. This overlap reduces the effective gap between treads, ensuring the 100mm sphere rule is met while maintaining the open, floating aesthetic.

Are Open Risers Allowed in Commercial Buildings?

In non-domestic buildings — offices, schools, retail, restaurants — Part K recommends the use of solid risers rather than open risers. This is because open risers create a risk of feet or walking aids becoming caught beneath a tread, which is a greater concern in high-traffic public environments. Open risers can be used in commercial settings where a risk assessment supports it, but solid risers are the default for compliance.

Winder Staircase Regulations UK

A winder staircase uses tapered treads to change direction without a full landing — saving space compared to a staircase with a quarter or half landing. Winders are common in L-shape and U-shape staircases where space is limited. Part K sets specific requirements for winder tread dimensions to ensure safety at the turn.

Winder Tread Going Requirements

The going of a winder tread varies across its width — it is narrower at the inside of the turn and wider at the outside. Part K requires that the going of winder treads is measured at the pitch line (typically 270mm from the inside edge of the staircase), and must comply with the same going requirements as straight treads.

Consistency Rule for Consecutive Winders

Where consecutive winder treads are used (e.g. a kite winder box with three or four tapered treads), all winder treads must have a consistent going at the pitch line. Winder treads that vary in width from each other — even within the turning section — are non-compliant.

Minimum Number of Winder Treads

Part K does not specify a minimum number of winder treads, but in practice a kite winder box should contain at least three tapered treads to achieve a smooth transition. A two-step winder box creates very acute taper angles that are difficult to walk and hard to make compliant — four treads is the recommended minimum for comfort and compliance.

Rise Consistency in Winder Sections

The rise of winder treads must be identical to the rise of the straight treads in the same flight. You cannot have a different riser height in the winder section — all risers throughout the flight must be consistent.

Loft Conversion Staircase Regulations UK

Loft conversions present unique challenges for staircase design — limited headroom, awkward geometry and restricted space often make it impossible to achieve a standard compliant staircase. Part K and Approved Document B both acknowledge this and provide specific guidance for loft conversion staircases.

Reduced Headroom Exception

Where a loft conversion staircase cannot achieve the standard 2000mm headroom due to the existing roof structure, Part K permits a reduced headroom — subject to conditions:

Alternating Tread Stairs (Space Saver Stairs)

Where there is insufficient space even for a standard staircase with reduced headroom, Part K permits the use of alternating tread stairs (also known as space saver stairs or paddle stairs) — but only in loft conversions, and only where there is no other practicable option.

Fire Escape from Loft Conversions

If the loft conversion creates a habitable room — a bedroom, study or living space — Approved Document B requires that there is a suitable means of escape in case of fire. For most two-storey houses being converted to three storeys, this means:

• The loft staircase must be enclosed in a fire-resisting structure (30-minute fire resistance)
• All doors opening onto the staircase enclosure must be fire doors (FD20 or FD30)
• Or alternatively, an escape window from the loft room meeting minimum size requirements (0.33m² opening area, min 450mm height and width)

This is a simplified overview — always consult Approved Document B and your Building Control officer for the full requirements specific to your property type.

Spiral Staircase Regulations UK

Spiral and helical staircases are not covered by the rise and going requirements of Approved Document K — instead, they fall under BS 5395 Part II, the British Standard for spiral and helical staircases. The requirements differ significantly from those for conventional stairs.

BS 5395 Part II – Key Requirements

Spiral Staircase Categories

BS 5395 Part II categorises spiral staircases by their intended use. The category determines the dimensional requirements and structural performance specifications:

Can a Spiral Staircase Be a Main Staircase?

Yes — a spiral staircase can serve as the main staircase in a private dwelling, provided it meets Category B requirements under BS 5395 Part II (minimum 1000mm width). However, most Building Control officers will scrutinise a spiral main staircase carefully, particularly regarding accessibility for less mobile users and the ease of moving furniture between floors.

Spiral Staircases as Fire Escapes

Spiral staircases can be used as fire escape routes under Approved Document B, but only in limited circumstances — typically for small numbers of people (fewer than 50) in low-rise buildings. For larger occupancies or taller buildings, a conventional straight-flight fire escape staircase is required. Always consult Approved Document B and your local Fire Authority for fire escape requirements specific to your building type.

External Staircase Regulations UK

External staircases — including garden access stairs, fire escapes, balcony stairs and commercial access stairs — are subject to both Approved Document K and, where they form part of a means of escape, Approved Document B and BS 9991. The dimensional requirements for external stairs differ slightly from internal stairs in some respects. For a full overview of Continox's bespoke external staircase service, visit our External Staircase page.

External Staircase Dimensions – Part K

Tapered Steps on External Staircases

Where an external staircase uses tapered steps — for example on a curved or turning garden staircase — Part K requires the going to be measured at the pitch line (270mm from the inside edge) and must be a minimum of 280mm for external stairs with tapered steps. The maximum pitch is 42°.

Weather Resistance & Corrosion Protection

External staircases must be designed to withstand UK weather conditions. Steel external staircases should be finished to BS EN ISO 12944 corrosion protection standards — typically hot-dip galvanised and powder-coated. Tread surfaces must provide non-slip performance in wet conditions — perforated steel, open bar grating or anti-slip coatings are all acceptable solutions.

Commercial vs Residential Staircase Regulations – Key Differences

The requirements for commercial staircases (offices, retail, schools, HMOs, apartment blocks) are significantly stricter than for private domestic stairs. This reflects the need to accommodate a wider range of users, higher footfall, and greater fire safety obligations.

Do You Need Building Regulations Approval for a Staircase?

Understanding when Building Regulations approval is required — and when it isn't — is important before starting any staircase project. The rules differ depending on whether you are replacing an existing staircase, installing a new one or carrying out structural changes.

How to Notify Building Control

For work requiring Building Regulations approval, you have two options:

• Full Plans Application — submit detailed drawings before work starts. Building Control approves the plans and inspects at key stages. Recommended for new staircases and complex projects.
• Building Notice — notify Building Control before starting work, without submitting full plans. Suitable for straightforward replacements. The completed work is inspected on site.

At Continox, we provide all necessary technical drawings and documentation to support Building Control applications as standard. You never need to manage the compliance paperwork yourself.

UK Staircase Regulations FAQ

Answers to the most commonly asked questions about UK staircase building regulations, Part K dimensions and compliance.

Staircase Nosing Regulations UK

Staircase nosings — the front edge of each tread — play an important safety role by defining the step edge clearly and providing a grip surface. Part K sets specific requirements for nosings in both domestic and non-domestic buildings, with additional guidance in BS 8300 (accessibility) and Approved Document M for buildings used by the public.

Nosing Overlap – Open Riser Staircases

For open riser staircases, each tread must overlap the tread below by a minimum of 16mm. This overlap serves two purposes: it reduces the open gap between treads (helping meet the 100mm sphere rule), and it provides a defined step edge that users can see clearly when descending.

Contrasting Nosings – Commercial & Public Buildings

For staircases in non-domestic buildings — offices, schools, retail, care homes, public buildings — Approved Document M and BS 8300 require that step nosings are visually contrasting from the tread and riser surfaces. This is an accessibility requirement designed to help visually impaired users identify each step clearly.

• Contrast strip width: minimum 55mm on the tread and 55mm on the riser
• Colour contrast: must be a light-reflectance value (LRV) difference of at least 30 points between the nosing and the adjacent surface
• Material: contrasting nosing must also be non-slip — stainless steel, aluminium or rubber inlaid nosings are all acceptable
• Full width: the contrasting nosing must run the full width of the tread

Non-Slip Nosing Requirements

Part K does not specify a mandatory non-slip standard for internal domestic staircase nosings, but Approved Document M requires that nosings in public and commercial buildings provide adequate slip resistance. For external staircases, non-slip tread surfaces are a practical requirement regardless of building type — particularly in wet conditions.

Part M – Accessible Staircase Regulations UK

Building Regulations Part M (Access to and Use of Buildings) sets requirements for the accessibility of staircases in new buildings and buildings undergoing material alterations. Part M works alongside Part K — where the two overlap, the more demanding requirement applies.

When Does Part M Apply?

Part M applies to:

• New dwellings — all new houses and flats must meet Part M Category 1 (Visitable Dwellings) as a minimum
• New non-domestic buildings — all new offices, retail, schools and public buildings
• Material alterations to existing buildings — significant changes that affect compliance
• Extensions — where the extension creates a new floor level

Part M does not apply to like-for-like replacements of existing staircases in existing dwellings — only Part K applies in those cases.

Part M Categories for Dwellings

Staircase Requirements Under Part M (Non-Domestic)

For non-domestic buildings, Part M requires staircases to be designed so that they can be used safely and independently by as wide a range of users as possible. Key requirements include:

• Minimum clear width: 1200mm for main staircases; 1000mm for secondary staircases
• Rise: Maximum 170mm (Easy Access standard)
• Going: Minimum 250mm
• Handrails: Both sides, continuous, 900–1000mm high, projecting 300mm beyond top and bottom risers
• Contrasting nosings: 55mm × 55mm minimum, LRV difference ≥30 points
• Landing width: Minimum equal to stair width
• Tactile warning surfaces: Corduroy hazard warning strips at top of stairs in public buildings

Tactile Paving & Warning Surfaces

In public buildings — transport hubs, shopping centres, schools, hospitals — corduroy hazard warning tactile paving must be installed at the top of each flight of stairs, set back 400mm from the nosing of the top step. This provides a tactile warning for visually impaired users approaching the staircase from the landing above.

Staircase Regulations in Scotland & Northern Ireland

The regulations covered in this guide apply to England and Wales only. Scotland and Northern Ireland have their own separate building standards, with some differences in staircase requirements. If your project is in Scotland or Northern Ireland, you must refer to the applicable regulations for that jurisdiction.

Key Differences – Scotland

Scottish Building Standards are broadly similar to Approved Document K but with some notable differences:

• The minimum going for domestic stairs is 225mm (vs 220mm in England and Wales)
• Scottish Standards use a Section 4 (Safety) framework rather than Part K terminology
• Building warrants (the Scottish equivalent of Building Regulations approval) are issued by Local Authority Verifiers rather than Building Control
• Completion certificates must be obtained from the Verifier before a building can be occupied

Key Differences – Northern Ireland

Northern Ireland's Building Regulations are administered by Building Control NI and are broadly aligned with the England and Wales Approved Documents, but maintained separately. The key staircase dimensions are largely identical. However, always check the current Technical Booklet H (Stairs, Ramps, Guarding and Protection from Impact) for the latest requirements applicable to your project.

7 Common Staircase Building Regulations Failures

Based on our experience designing and installing bespoke staircases across the UK, these are the most frequently encountered Building Regulations compliance failures — both in existing staircases and in new designs that reach Building Control inspection. Avoiding these mistakes at the design stage saves significant time and cost.

Do Building Regulations Apply to Replacement Staircases?

One of the most frequently asked questions about staircase regulations is whether Building Regulations apply when you are replacing an existing staircase rather than installing one in a new building. The answer depends on the nature and extent of the work.

Like-for-Like Replacement

A true like-for-like replacement — where the new staircase has the same position, configuration, dimensions and materials as the old one — is generally considered a repair rather than a material alteration, and may not require Building Regulations approval. However, this is a narrow exemption and in practice most staircase replacements involve at least some change.

When Building Regulations Apply to Replacements

Does the Replacement Need to Meet Current Regulations?

This is a common concern — particularly for older properties where the existing staircase may have a steeper pitch, lower headroom or narrower width than current regulations require. The general principle is:

• Where Building Regulations approval is required, the new staircase must meet current Part K requirements
• You cannot use the existing non-compliant staircase as a justification for installing a new non-compliant one
• If achieving full compliance is genuinely impossible due to the existing structure (e.g. insufficient floor-to-ceiling height for 2000mm headroom), Building Control may accept a pragmatic solution — but this must be agreed in advance, not assumed

Regularisation – Work Done Without Approval

If a staircase was installed without Building Regulations approval when approval was required, it is possible to apply retrospectively for a Regularisation Certificate from the local Building Control authority. This involves Building Control inspecting the completed work and certifying it as compliant — or identifying what needs to be changed to achieve compliance.

Regularisation is not always possible — if the work cannot be inspected adequately (e.g. if structural elements are concealed), Building Control may decline to issue a certificate. In this case, the work may need to be partially exposed or redone.

Planning a New Staircase? Explore Our Range

Now you understand the regulations, the next step is finding the right staircase for your project. Continox designs and installs bespoke staircases across the UK — fully compliant with Part K, designed in 3D before manufacture, and installed by our in-house team.