Carpentry is an age-old profession and has acquired almost a language of its own, especially to those uninitiated in the trade. The different names for the parts of a staircase trace the history of the profession. Balustrading, gooseneck, bullnose, volute, and newel are just some of the terms that can cause confusion and raised eyebrows.
In this guide, we’ll take a look at the different parts of a stairway and explain the terminology. We’ll discuss different kinds of staircases, dimensions, and Building Code requirements. By the end of the guide, you’ll have a better understanding of the parts of stairs and what different terms mean.
Contents (Jump to Topic)
- Parts of a Staircase: A Guide to Stair Part Terminology
- Typical Residential Staircase Dimensions
Parts of a Staircase: A Guide to Stair Part Terminology
A staircase is made up of different components that function together and are common from one stairway to another. Some designs incorporate common parts to form uniquely shaped stairs or arrangements. In this section, we’ll identify what the different parts of a staircase are called and take a look at their purposes.
Note: For Code requirements for stairways and continuity in our guide, we reference Section R311.7 of the 2018 International Building Code (IRC) and its subsections which guide national and local codes in the United States and Canada. The IRC identifies minimum requirements to which there may be exceptions. Always check local inspectors, codes, or with a Structural Engineer.
A staircase is used to connect or bridge different vertical levels or elevations by breaking the distance into smaller, more manageable vertical lifts or risers. The overall vertical distance or rise is divided into smaller increments based on the horizontal distance available. The shorter the horizontal space, the steeper the slope, angle, pitch, or rake of the staircase.
To lessen the slope, stairways may be curved or broken into staircase sections or flights with or without landings to form a switchback type path from one elevation to another. The more uniform the lifts or risers, the easier it is to traverse. Staircases are made from wood, stone, concrete, steel, glass, plastic, vinyl, or combinations of different materials.
Stairs need to be a minimum of 36-inches clear width (R311.7.1) above the height of the handrails and have headroom of 6’-8” (R311.7.2). A flight or section of stairs isn’t to exceed a vertical rise between floor levels or landings of 151-inches (R311.7.3). There are always exceptions to the rules, so check your local code.
Balusters and Spindles
Spindles and balusters are terms used interchangeably by many people but they are not the same. They are vertical posts that prevent people falling from one height to another. Baluster is a term used to describe the individual vertical support for a railing. Balusters sit on a horizontal base like a step, floor, landing, or deck and form a low wall or barrier. They can be made of stone, concrete, wood, iron, plaster, or other materials. The term originally meant jugs, vases, or posts with the bulbous shape of the pomegranate flower or balaustro (Italian).
Spindles commonly refer to slender vertical pieces that connect a top railing or handrail with a bottom or base rail. They do not sit directly on steps, landings, decks, or floors. The top and bottom rail are supported by posts at either end. Spindles are square or rounded pieces of wood, or ornately turned or carved and functioned to prevent accidents, which is why they are also known as guards, pickets, and uprights. Today, they are made of wood, metal, or other materials. The term originated from old English, Saxon, Frisian, and German, and referred to a small, rounded wooden stick used in hand-spinning.
Balusters may be carved, poured, or wrought in numerous shapes and styles. Ornate balusters were, and are, common in main staircase designs and embellish or accent the wealth or status of the home and occupants. Many mimic historical or architectural pieces from times long past or are recycled from demolished residences, and others are derived from the imagination of modern designers.
Plain Staircase Baluster
Plain balusters are simple in design and taste and were common in second stairways. They often showcase craftsmanship on a more muted or reserved artistic level. Plain may mean square, rounded, or turned wooden or wrought iron or steel spindle-like components that sit on or are set into the stair or landing surface and support the handrail.
Balustrading is all the components that combine to form a low wall or barrier, or barrister, to prevent people from falling from one level to another. They are often found on stairs, landings, floors, terraces, walkways, bridges, and sometimes even the eaves of important buildings. It is made up of balusters, the top rail or banister, and any other architectural pieces that support the top rail.
Barriers with spindles between a top or handrail and a bottom or base rail supported by posts also prevent falls from one level to another. Spindles differ from balusters and the low barrier they form isn’t a balustrade. It was often referred to simply as a railing or guard, however, some people do call it a balustrade.
Handrails & Guards
Handrails may consist of railing and mounting brackets or supports and run parallel to the slope of the stairs. They provide support and stability when ascending or descending a stairway to guard against falls from one elevation to another. Handrails must be on at least one side of staircases with four or more risers (R311.7.8) and must be 34” to 38” in height (R318.104.22.168). The ideal height for short or tall to grab if needed, and also high enough to prevent accidentally falling over it.
Handrails may project into the pathway up to 4-1/2” (R322.214.171.124) and there must be 1-1/2” or more between the rail and the wall (R3126.96.36.199). Handrails must run from above the lowest riser continuously to above the topmost riser (R3188.8.131.52). However, the length may be broken by newel posts to change direction and follow the path of the stairs.
The grip size of handrails is also regulated (R3184.108.40.206) to ensure it is graspable. It may have a diameter between 1-1/4” and 2” if round, or up to 2-1/4” if oval in shape. Handrails may be wider but must have a recess for fingers to grip.
Banister refers to the barrier or guard formed by the vertical uprights – the newel posts and balusters – and capping or top rail. It is commonly found on the exposed or open side or sides of a stairway or as a parapet around open landings. Some ornate banisters may have a cross-sectional width of 5” to 6”, while simpler ones may be 2” across.
A handrail banister may refer to a handrail mounted to a wall with support brackets or to a banister with baluster supports. It could mean a handrail supported at each end and acting as an intermediate or middle railing on wide staircases. It is also used to identify railings supported by less ornate or spindle-like balusters.
A base rail runs parallel to the handrail or cap rail and is usually raised to make sweeping or shoveling easier. The base rail often supports spindles that connect to the handrail or top rail and guard against falls and accidents.
A volute is the section of the handrail at the foot of the stairs that horizontally curves 360° to the left or right – left or right-handed when looking up the stairs. It is a scroll-like detail that leads into the handrail at the first step up and is also known as a monkey’s tail. It provides an elegant or graceful end or beginning (depending on the direction of travel) to a handrail and staircase.
A turnout has an undermount or pin-top newel post supporting it and is similar to a volute at the foot of a staircase, except it only curves 90° to the left or right. A turnout can also refer to a curved or squared handrail section that connects railings as flights change direction to maintain a continuous handrail.
A gooseneck is short sections of vertical and curved handrail connected and used to raise the height of a sloped railing where it joins a higher horizontal railing at a landing, balcony, or bend.
A rosette is used in place of a half-newel to finish where a railing ends at a wall. Mainly a decorative piece, they can help secure the top rail to the wall.
A landing is the immediate floor area at both ends of a stairway, used for changing direction and rest. It is also a flat platform between two flights where the stairs change direction or meet another flight. A landing is also required to break a vertical rise greater than 151-inches (R311.7.3).
The minimum width of a landing should be 36” or the width of the staircase, whichever is greater, and extend no less than 36” in the direction of travel (R311.7.6). Landings used at entry stairways provide a rest and wait area and must be a minimum of 36” in depth and at least as wide as the entry they serve (R311.3); especially if the door swings outward.
Landings that extend in the direction of travel equal to the width of the staircase are often called half landings. This commonly occurs where two flights of stairs meet at 90°. In some situations, a landing may only extend in the direction of travel half the width of the stairway, it is termed a quarter landing. A quarter landing may also be used to identify a winding step that spits a landing into two wedge-shaped steps.
Newel posts are key or principal vertical support balusters or posts that carry and anchor the railing. Made of wood, steel, stone, or concrete, they often extend above the level of the railing where it terminates or changes direction at a landing. Newel posts are securely fastened to the structural framework of the staircase and floor.
The starting newel post is at the base of the stairway and often heavier and more ornate than other posts. If made of wood or steel, it commonly extends through the floor to the bottom of the joists to which it is bolted.
A pin-top newel is an intermediate support post that inserts into the handrail. It is used to support an unbroken handrail or turnout. It may or may not differ from other balusters. It may also fasten through the stair to the inside or outside of the stringer.
A half newel post is used where a balustrade, banister, guard, or railing terminates at a wall. It is a newel that has been vertically sliced in half and looks like a full post has been embedded into the wall. Some choose to use a rosette instead of a half newel or simply terminate the rail at the wall.
A newel cap or finial often caps the starting newel. It may also be used over pin-top posts or balusters for decorative effect. More ornate caps are often carved figures, oversized spheres, urn-shaped planters, and some are even illuminated glass shapes.
The riser is the vertical component or face that connects two treads and runs between the stringers. It closes the opening under the front or over the rear of a step and adds support across the tread. Some staircases do not have a riser and are referred to as open tread or open stairs.
The distance between the upper horizontal surface of one step or tread to another cannot exceed 7-3/4” (R3220.127.116.11), which by default, is also the maximum height of a standard residential riser. Risers may be made of wood, steel, concrete, glass, or other materials and commonly range from 4” to 7-3/4” in height depending on the gap between treads. The wider size facilitates fastening the riser into place.
Riser wedges are wedge-shaped pieces of wood and are part of the riser fitment used to tighten the riser into place after it is installed. They are commonly used with closed stringers and are driven into the dadoes cut for the riser.
The treads are the horizontal surfaces of the staircase that are stepped on when ascending or descending. The treads combine for the total distance the stairs go or run. Treads are usually rectangular and must have a uniform depth of 10” or more, measured horizontally from the front edge of one step to the lead edge of the next (R318.104.22.168).
Treads that are wedge-shaped are also known as winder treads. They are used to make turns and must also have a minimum 10” step clearance at the walk line (R322.214.171.124.1). Treads commonly are made of wood, steel, concrete, stone, or other materials. There is also one less tread than the number of risers.
Tread wedges are similar to riser wedges. They are commonly found on closed stringers where the step boards are enclosed between the stringer faces. They are used to tighten the fit of the tread and curtail squeaks after it is installed in its dado.
The tread-riser block, also known as a glue block, is a piece of squared or triangular wood or metal used to connect the inside upper face of the riser to the underside of the tread.
Straight treads are a uniform rectangular shape. All treads or steps are the same width and depth, and the riser is square with the treads and stringers.
Convex treads have a curved leading edge between the stringers, and the riser is also curved to match.
The return tread or nosing is the finished edge of the step side that projects past the outside stringer. It matches the forward nosing or is a piece of molding rounded or fluted to match the front edge of the step. The return provides a finished edge, may hide the seam between the stringer and tread, and also may box in balusters inset into the tread.
Stair Tread Nosing
Many step treads and landings have a nosing that protrudes past the vertical line of the rising below. The nosing finishes the tread face and extends its length. The curvature is visually appealing and makes the edge less abrupt and easier to use. It also may cover and hide the seam where the riser meets the step, plus, a curved edge is less likely to splinter or wear.
Nosings should project between 3/4″ and 1-1/4” unless the step has a depth of 11” or more (R3126.96.36.199) in which case they aren’t necessary. The forward edge may have up to a 1/2″ bevel or a curvature with a radius of 9/16” or less. Different shaped or curved nosings are known by a variety of names.
A bullnose is a half-round or half-moon shaped nosing and has a smooth rounded edge. The leading edge of the step may be rounded or a shaped piece of wood added. The bullnose extends the tread edge outward and visually softens the edge.
A double bullnose combines two bullnoses to flow together and create a thinner, more elegant looking step. The effect looks like the number 3, except the lower bullnose is recessed below the first, for a waterfall effect.
Stairs that have a tread depth of 11” or more often have a square or 90° edge. Stairs less than 11” may have a flat or square looking edge which actually has a slight 1/32” radius bevel at the upper edge. The bevel helps minimize damage and wear to the edge.
The eased edge nosing is similar to the square edge but has a 1/8” to 1/4” radius curve at both the top and bottom edge of the nose facing. It provides a smoother transition between steps and greater protection to the edge from denting or splintering.
The return nosing creates an effect similar to the return tread. It is a piece of trim shaped to match the leading edge of the tread. It provides a smooth, warmer finish than the end-grain of the tread.
Similar to the return nosing but on both the left and right edge of a tread that is exposed at both ends.
Stairs that don’t require an overhang may have a mitered edge where they meet the riser, forming a 90° or greater angle between the two without a visible seam. The effect is to make the stair look like it is made from a solid piece of wood, for a clean, minimalistic look.
A decorative piece of cove, 1/4-round, or fretwork molding fastened under the nosing where it meets the riser. It adds a touch of beauty or whimsy, hides the seam between the tread and riser, and may provide additional support to the tread edge.
The step is the horizontal component of the staircase that is tread upon when ascending or descending, combined with the vertical riser. The step depth, or going, is measured from the front edge of one step, horizontally to the front edge of the next step and must be at least 10” (R3188.8.131.52). Steps can be wooden, metal, stone, concrete, plastic, glass, or any other acceptable material, and may have a slope of 2% or 1” vertically every horizontal 48” (R311.7.7).
The starting step is the first step in a staircase. It may be the same dimensions as the other steps in the stair, or it can be more decorative and wider.
A curtail step is also the first step but it projects out past the newel post and the slope-line or stringer of the staircase. Occasionally, the second step may also project out past the stair line, but not as far as the first step. Curtail steps are crafted in a variety of shapes or designs, and often provide additional support for the newel post.
A common curtail projection is one that curves 90° to connect with a wall, or 180° to end against the stringer. They are respectively referred to as a half or full bullnose, or a quarter or half-circle. Some starting steps may protrude on both sides of the stair line and those curved are called a double bullnose.
A feature step or stair adds artistic or architectural boldness and interest. They may combine different materials like wood, metal, and glass. It often includes a decorative piece that acts as the starting newel post or baluster.
Winders are triangular-shaped treads that are narrower at one end than the other. They are commonly used to continue the stair path as it changes direction instead of using a landing; thus, requiring less run or horizontal distance. Circular or spiral staircases are formed using winder stairs.
A 90° corner or turning may be constructed using two or three winders. Two winders forming a 90° angle are known as 1/4 landings. When three winders are used to complete a 90° turn, the middle tread is referred to as a kite winder or a kite double winder, due to its shape. The depth at the walkline for winders must also be a minimum of 10” as measured 12” inward from the widest portion of the tread’s walking surface (R311.7.4).
The string, stringer, or stringer board is the sloped structural support for a flight of stairs. They are made of wood, metal, concrete, stone, or other materials. Treads and risers are commonly supported by one or more stringers, although other support methods are used too. A stringer can’t have a vertical rise of more than 151” (R311.7.3). Stringers may have an exposed or finished face.
Those that are cut or mitered may be called sawtooth or open stairs, and the treads and risers often rest on and against the cut teeth. The narrow distance from the base of the cut teeth to the lower sloped edge of the stringer is called the waist. The thickness of the waist depends on the type of material used and the overall dimensions of the stringer.
Stringers that aren’t notched are termed closed, housed, routed, or boxed stairs. The treads and risers are set into dadoes routed out of the inside face of the stringers, or they rest on blocks fastened to support them.
Western stringers are boxed or closed stringers. Stairs with no riser board are termed open, while those with riser boards are closed.
Eastern stringers are sawtooth or open stringers. Stairs with risers are called closed, and those without risers are open.
A mono stringer is a heavy, beam-like sawtooth stringer that centrally supports treads from below. Mono stringers do not have risers and are considered open.
Skirt Board (String)
A skirt board is used to trim the structural part of the stairs running against a wall or where a visible stringer isn’t in good condition. It is often an unbroken board or veneer that trims and accentuates the stringer where it is exposed. In most situations, the closed wall and open outer stringers form the skirt boards. In others, it is a finishing board or veneer (often of more exotic and expensive wood) that covers the stringer and is cut to fit around the riser and tread profile.
It is a finishing touch that accentuates the staircase. Another method is to use trim that blends with the baseboard used in the rest of the area around the staircase for a continuous effect. The outer skirt board may be left plain and clear, or it may be filigreed with fretwork, ornately carved wood, or molded plasterwork.
A closed stringer or string is also called a housed, boxed, solid, or routed stringer and has treads and risers set into or against its exposed face so their ends are hidden. The upper edge forms an unbroken diagonal line from one end to the other.
A cut stringer or string is also known as a mitered, notched, sawtooth, or open stringer. It is cut so the treads rest on and the risers against a cut out right angle, allowing the step ends to be seen.
A wall string commonly is flush to a wall and the risers and treads routered, boxed, or housed into the stringer.
String capping is a continuous piece of molding or trim that runs atop the diagonal wall stringer. It finishes the stringer and masks any gap between the wall and the staircase.
Outer (open) String
The outer string does not run along a wall but is exposed or ‘open’. It may be a closed or cut stringer and often showcases spindles or balusters and a handrail. The exposed string is also called a skirt board.
The triangle formed by the outer or open string and the floor may be left open or framed and closed in. The framed and enclosed triangle is referred to as the spandrel.
Apron Lining / Fascia
The apron refers to the horizontal joists or bulkhead of the framed opening or well hole through which a stair accesses the floor above. The joists may be covered with drywall or left exposed. Exposed joists often receive an apron lining or facia of MDF, solid wood, or veneer to match the stringer or skirt board. The apron lining also covers the exposed or forward joist of a landing under a balustrade.
The soffit is the underside of a staircase and is often finished to match surrounding ceilings.
Typical Residential Staircase Dimensions
The typical residential staircase dimensions have only been consistently regulated in most areas of North America since the 1940s. Although the IRC and its minimum safety regulations are accepted in much of North America today, there are still some areas with unique codes, and others with none. It is always best to check with your local jurisdiction before beginning a building project.
Handrails must be between 34” and 38” high measured vertically from the finished surface of the sloped plane (R3184.108.40.206) of the staircase.
A tread must have a minimum depth of 10” measured horizontally from its leading edge to the leading edge of the next step (R3220.127.116.11). The maximum deviation from the greatest tread depth to the smallest in a flight shall be 3/8” or less.
The height of a riser is measured from one horizontal step surface vertically to the horizontal level of the next step and shouldn’t be greater than 7-3/4” (R318.104.22.168). The greatest deviation between the highest rise and the lowest rise in a flight can’t exceed 3/8”.
Treads less than 11” deep require a nosing projecting from 3/4″ up to 1-1/4” (R322.214.171.124) with the greatest deviation being 3/8”. The nosing on treads, landings, and floor openings must have a curvature radius of 9/16” or less, or a maximum bevel of 1/2″.
The width of a staircase must be a minimum of 36” above the handrail to the headroom height (R311.7.1). The minimum clear stair or tread width at and below the handrail level is 31-1/2” if there is only one handrail or 27” if there are two.
Central pole or spiral staircases often require less horizontal space to traverse a height than standard sloped staircases. Steps are commonly wedge-shaped, wind around a central support or post, and have a railing guarding the outer or open side. The clear width of the tread at and below the handrail can’t be less than 26” (R3126.96.36.199).
The headroom must be at least 6’-6”, and the radius of the walkline can’t exceed 24-1/2”. Treads must be identical, have a depth of 6-3/4” or more at the walkline, and have a rise no greater than 9-1/2”. Modern central pole stairways can be kit or custom made and come in wood, metal, or glass, although they are still available in stone and even concrete.
Building stairs is a specialized component of construction. Most carpenters and DIYers can build them, although many prefer to leave it to those who have chosen to specialize in stair construction. The terminology used to identify the different parts of stairs may be confusing as it is often shared with other facets of construction. The names of stair parts commonly identify their purpose; however, it is the building code that determines the minimum dimensions and safety requirements required for construction. I hope you now have a better understanding of stair parts and the code requirements.