The short answer
A new staircase, or one whose dimensions or layout you change, must comply with Part K of the building regulations (Approved Document K), so building control approval is normally needed. For a private domestic stair that means a maximum rise of 220mm and a minimum going of 220mm, a pitch no steeper than 42°, at least 2m (2000mm) of headroom above the pitch line, a handrail at around 900mm high on at least one side (both sides if the flight is wider than 1m), and guarding with no gap a 100mm sphere can pass through. Simply cladding existing treads without altering the dimensions does not normally require notification, but any change to the geometry, balustrade or structure brings Part K into play — so confirm your specific works with your installer or building control before starting.
Whether you need building regulations comes down to one question: are you creating or altering a stair, or just refreshing the surface? The Part K rules below are what a compliant private stair must meet.
Part K in brief (private stairs)
- Max rise220mm
- Min going220mm
- Max pitch42°
- Min headroom2m (2000mm)
- Baluster gapno 100mm sphere
When Part K applies
A new staircase, or any work that changes a stair's dimensions, geometry or structure, is covered by Part K and normally needs building control approval — whether that is a full replacement, moving the stair, or altering the rise and going. By contrast, cladding existing treads with new oak or pine over the same dimensions, or redecorating, does not usually require notification because you are not altering how the stair performs. Where a new flight serves a loft, only the stair element is the staircase question here; the wider conversion is a separate matter. If you are unsure, confirm with your installer or local building control before work starts.
The Part K rules for a private stair
Approved Document K sets out the limits for a private domestic staircase. The headline figures are a maximum rise of 220mm and a minimum going of 220mm, a maximum pitch of 42°, a clear headroom of at least 2m above the pitch line, a handrail at roughly 900mm high on at least one side (both sides over 1m wide), and guarding designed so a 100mm sphere cannot pass through any gap. These exist so a stair is safe to use and falls are prevented, and they are what building control checks against on a new or altered flight.
| Part K requirement | Private stair | Why |
|---|---|---|
| Maximum rise | 220mm | comfortable, safe step |
| Minimum going | 220mm | enough foot depth |
| Maximum pitch | 42° | not too steep |
| Minimum headroom | 2m (2000mm) | clearance above pitch line |
| Handrail height | ~900mm | support and guarding |
| Baluster gap | no 100mm sphere | prevents a child falling through |
General guidance for private domestic stairs — confirm your case with building control. Source: Approved Document K, Planning Portal.
Want a stair built to Part K?
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Frequently asked questions
Do you need building regulations for a new staircase?
Yes. A new staircase, or one whose dimensions or layout you alter, must comply with Part K (Approved Document K), so building control approval is normally needed. Simply cladding existing treads without changing the dimensions does not usually require notification.
What are the Part K rules for a domestic staircase?
For a private stair: a maximum rise of 220mm, a minimum going of 220mm, a pitch no steeper than 42°, at least 2m of headroom above the pitch line, a handrail around 900mm high, and guarding with no gap a 100mm sphere can pass through.
Does cladding a staircase need building regulations?
Cladding existing treads without altering the stair's dimensions does not normally require notification. If you change the geometry, balustrade or structure, Part K applies — confirm your specific works with your installer or building control first.
Sources & further reading
- Planning Portal — Approved Document K
- Approved Document K (Protection from falling, collision and impact)
Figures on this page are typical UK ranges drawn from published sources and depend on your specific staircase. They are guidance, not a quotation.