Staircase parts glossary and jargon buster
Parts Glossary & Jargon Buster
Written by Scott Jones, The Stair Guys, independent staircase measuring and sourcing specialists·Last updated
Buying a staircase is a lot easier when you know what the parts are called, because the words are how you ask the questions that matter. Here is the plain-English version of the lot, grouped so it actually makes sense, with the jargon that trips people up untangled at the end.
The steps
The bits your feet meet, and the three measurements every stair is set out from. The figures behind these live in our private staircase dimensions guide.
- Tread
- The flat part of a step, the bit you put your foot on.
- Riser
- The upright face between one tread and the next. It can be solid timber, plywood or MDF, and they are not equal: solid is best, plywood holds a screw well, MDF is the cheap one that splits when screwed.
- Nosing
- The front edge of a tread where it overhangs the riser below. On an open-riser stair the treads have to overlap by a set minimum.
- Rise
- The vertical height of a single step. Every rise on a flight must be equal, or the odd step becomes a trip hazard and fails the regs.
- Going
- The horizontal depth of a step, measured from the front of one tread to the front of the next. It is not the same as the tread board, which is deeper because of the nosing overhang.
- Pitch
- The angle of the whole flight. A domestic staircase cannot be steeper than 42 degrees.
The structure
The parts that carry the stair and tie it into the building.
- String (stringer)
- The long raked board that carries the treads and risers along each side of the flight. Its thickness is a quality marker: 32mm has long been the sign of a good stair, 27mm is the thinner, cheaper section a lot of volume housebuilding uses.
- Closed (housed) string
- A string with the treads and risers set into routed housings, so the ends of the steps are inside the board.
- Cut (open) string
- A string cut to the profile of the steps so the tread ends are visible from the side.
- Wall string
- The string fixed against the wall. It has to be scribed to fit a wall that is never perfectly straight.
- Trimmer
- The structural timber framing the edge of the floor opening the stair rises through. The top of the stair should be carried by it, not left hanging off a bolted post.
- Flight
- A continuous run of steps between floors or landings.
- Landing
- A flat platform breaking up a stair, at a floor or partway (a half or quarter landing). It resets a flight and must be at least as wide as the stair.
The balustrade
The guard along the open side. The rules for its height and gaps are in our guides to guarding and handrails.
- Balustrade
- The whole side guard of a stair or landing: the handrail, the spindles and the rails that hold them.
- Newel post
- The main upright post at the bottom, top and turns of a stair that anchors the balustrade and carries the handrail. It can be solid, or wrapped, which is a jointed core faced with thin timber and capped to hide the end grain.
- Baluster (spindle)
- The vertical bars filling the gap between the handrail and the base rail. No gap may let a 100mm sphere pass through.
- Handrail
- The rail you hold, 900mm to 1000mm high on a domestic stair. It is far stronger tenoned into the newels than butted up and screwed.
- Base rail (shoe rail)
- The bottom rail that the spindles sit into, running along the top of the string.
Turns and steep stairs
How a stair changes direction or climbs a tight space. More on winders and space-savers.
- Winder
- A tapered (kite) tread that turns a stair through a corner instead of a flat landing. Its going has to hold up along the walk line and stay at least 50mm at the narrow end.
- Walk line
- The path you actually tread, used to measure the going of winder treads, taken along the centre of a stair under a metre wide.
- Space-saver (alternating tread)
- A steep stair with treads cut for one foot each, left then right. Only allowed where a conventional stair genuinely will not fit.
Joinery and the jargon that trips people up
The terms that hide the difference between a good stair and a cheap one. These feed straight into the questions to ask and what you are actually getting.
- Pitch line
- The imaginary line running across the nosings of the treads. Headroom, handrail height and guarding height are all measured from it.
- Tenon and mortise
- A joint where a tongue (the tenon) on one part fits a slot (the mortise) in another. A handrail tenoned into a newel is far stronger and squarer than one butted and screwed.
- Engineered timber
- A component built from a timber core with a solid layer on top. Often more stable than solid and perfectly legitimate, but not the same thing as solid, and it should be disclosed.
- Finger-jointed
- Short lengths of timber glued end to end. Fine under paint, but it shows badly under a stain, so quality makers use solid clear timber where it will be seen.
- Bespoke vs made-to-order
- Truly bespoke means designed freely to your space with no fixed menu. Most "bespoke" stairs are really made-to-order from set components to confined dimensions. Both are fine, as long as you are told which you are buying.
- Dry fitting
- Assembling the whole staircase once in the workshop before it ships, to catch any fault while it can still be fixed rather than in your house. One of the most important things to ask about.
Frequently asked
What is the difference between the rise and the going of a stair?+
The rise is the vertical height of a step; the going is its horizontal depth, measured from the front of one tread to the front of the next. The going is not the same as the tread board, which is deeper because of the nosing overhang.
What is a string on a staircase?+
The string is the long raked board that carries the treads and risers along each side of the flight. Its thickness is a quality marker: 32mm is the traditional sign of a good stair, while 27mm is the thinner, cheaper section used a lot in volume housebuilding.
What is a newel post?+
The main upright post at the bottom, top and turns of a stair. It anchors the balustrade and carries the handrail. It can be solid or wrapped, where a jointed core is faced with thin timber and capped to hide the end grain.
What does a 100mm gap rule mean for stair spindles?+
No gap in the balustrade, including between the spindles, may be large enough to let a 100mm sphere pass through. It applies whether or not there are young children in the home.
Related guides
- Is a newel post structural? Yes, usually, and here is whyA newel post is typically structural, not just decorative. The strings frame into it and it is notched over the trimmer at the floor opening, so it helps hold the staircase together and ties it into the structure. That is why you cannot simply remove or move one.
- How a wooden staircase is put together, and why stairs creakA traditional timber staircase is a joinery assembly, not a nailed one: treads and risers are housed into grooves in the strings and locked with glued wedges and glue blocks. Most creaks come from one of those working loose.
- Feature bottom steps: bullnose, curtail and D-endThe bottom step is often shaped as a feature. A bullnose has a rounded end that returns to the front, a curtail wraps around the newel in a scroll, and a D-end curves at both sides. The shape sets the tone at the foot of the stair and where the bottom newel sits.
- Timber handrail profiles: mopstick, pigs ear, and wall vs balustrade railsHandrail profiles are the shapes a handrail is milled to. A mopstick is round and easy to grip, a pigs ear (lambs tongue) is a slim rail fixed straight to the wall, and a grooved profile carries the spindles on a balustrade. A wall-mounted rail and a balustrade rail are different jobs.
- Continuous and wreathed handrailsA continuous handrail flows over the newel posts in one unbroken line, turning corners and rise changes with curved sections called wreaths, instead of stopping at each newel. It is skilled, made-to-measure joinery, which is why it costs more than a post-to-post rail.
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