What is the rise, going and pitch of a staircase?
The three numbers that decide whether a staircase is comfortable, safe and lawful, the relationship between them, and why every step in a flight must be identical.
- Difficulty
- intermediate
- Time
- 9 min
- Read
- 5 min
- Safety
- warning
Short answer
Rise is the vertical height of one step, going is the horizontal distance from one nosing to the next, and pitch is the resulting angle. Approved Document K's guidance for a private stair in England is a maximum rise of 220mm, a minimum going of 220mm and a maximum pitch of 42 degrees, with twice the rise plus the going falling between 550mm and 700mm, and at least 2m of headroom. Every rise in a flight must be equal, and so must every going.
Stairs feel right or wrong long before anyone measures them, and the reason is arithmetic. The relationship between how far your foot travels forward and how far it has to lift is what your body has learnt from every other staircase, and a flight that breaks it is tiring going up and dangerous coming down.
Safety
Step by step
- Measure the rise properly.The vertical distance from the top of one tread to the top of the next. Measure the total floor-to-floor height and divide by the number of risers rather than measuring one step, because that is how the flight was set out.
- Measure the going properly.Nosing to nosing horizontally — not the depth of the tread board, which includes the overhang. This trips people up constantly and it is why a stair can measure comfortably and still be short on going.
- Understand the pitch.The angle of the pitch line drawn along the nosings. It follows from the rise and the going rather than being chosen. Approved Document K limits a private stair to 42 degrees.
- Apply the comfort relationship.Twice the rise plus the going should fall between 550mm and 700mm. It comes from the geometry of a walking stride, and it is what separates a flight that feels normal from one that is within the limits and still feels wrong.
- Check the headroom.At least 2 metres measured vertically from the pitch line, over the flight and over the landings. This is the constraint that most often decides where a new stair can go, particularly in a loft conversion.
- Insist on consistency.Every rise in a flight equal and every going equal. A single odd step at the top or bottom is the classic cause of a fall, because the foot has already learnt the rhythm of the flight.
- Understand winders.Tapered treads used to turn a flight without a landing. They have their own rules, because the going varies across the tread, and the narrow end is where people fall. They are permitted and they are less safe than a landing.
- Treat any change as controlled work.A new stair, an altered stair, or a stair added in a loft conversion is building control work in England, Wales, Scotland and Northern Ireland alike, though each publishes its own technical document. The inspector, not a table, decides.
Tips
- Adding a thick new floor covering to the landing at the top of a flight reduces the top riser and increases the risk of a trip. It is a small change with a real consequence and it is easy to overlook when re-flooring.
- In a loft conversion, headroom over the new flight is almost always the binding constraint, and it is worth establishing before the rest of the design is drawn.
- Older stairs frequently do not meet the current guidance and do not have to. The requirement bites when a stair is built or altered, not because a house is old.
Common mistakes
- Measuring the going as the depth of the tread board — The going excludes the nosing overhang. Measuring the board makes a stair look compliant when it may not be, and it is the most common measuring error on stairs.
- Making up a height difference with one odd step — It is the single most reliable way to make a staircase dangerous. Human gait adapts to the flight after two or three steps and does not expect an exception.
- Fitting an alternating tread stair to save space without checking where it is allowed — Alternating tread stairs are permitted only in specific circumstances, typically to a single room in a loft. They are not a general space-saving option.
If it doesn't work
The stairs feel steep and tiring
Cause: A high rise combined with a short going, so the 2R+G figure is at or above the top of the comfortable band — Fix: Measure it and find out. Nothing can be done to an existing flight geometrically, but knowing the pitch is what tells you whether a stairlift, a handrail on both sides or a rebuild is the sensible response.
People keep catching a foot at the top step
Cause: An inconsistent rise, most often introduced by a floor covering added later — Fix: Measure every riser in the flight with a tape from tread to tread. A single one that is different by more than a few millimetres is the answer and it can usually be corrected in the covering.
A loft conversion design has been rejected on the stairs
Cause: Headroom, pitch or going that cannot be achieved in the space available — Fix: This is the normal difficulty with loft stairs and it is a design problem rather than an argument. Moving the head of the flight, changing its direction, or using a dormer to gain headroom are the usual routes.
Questions people ask
Do these figures apply to my existing stairs?
Not retrospectively. They apply when a stair is built or altered. An older stair that is steeper than the current guidance is not unlawful, though it is worth knowing if anyone in the house is unsteady.
Is it different in Scotland and Northern Ireland?
Yes. Scotland works to the Technical Handbooks and Northern Ireland to the Technical Booklets, and the values and the terminology are not identical to Approved Document K. Wales publishes its own version of the Approved Documents.
What is a spiral or helical stair required to do?
There are specific provisions for them and they are generally only acceptable as the main stair in limited circumstances. As a secondary stair to a single room they are more common. It is a case to take to building control early.
How much does the guarding matter next to the geometry?
Equally. Guarding on a flight and on a landing must be at least 900mm high, and no gap in it may allow a 100mm sphere through — that figure exists because of what a small child can get a head through.