Staircase Anatomy - Over The Post Rail Systems

A staircase consists of two systems-  the step system (treads, risers, stringers, nosing) and the railing system (handrail, balusters, newel posts, balustrade). Together, these components form the complete staircase. The railing system divides further into over-the-post and post-to-post configurations, which differ in how the handrail connects to the newel posts. Understanding these parts by name helps homeowners, contractors, and designers communicate clearly during a remodel or new build.

Key Takeaways

• A staircase has two primary systems-  the step assembly (tread, riser, stringer, nosing) and the railing assembly (handrail, balusters, newel posts, balustrade).
• The handrail is the part you grip for support. Balusters (also called spindles) are the vertical posts supporting it. The newel post is the large anchor post at the bottom, top, and turns of the staircase.
• A balustrade is the complete railing system- handrail, balusters, and newel posts together. A banister is informal language for the handrail or the full balustrade.
• Over-the-post systems have a continuous handrail that runs over the top of the newel posts, requiring handrail fittings (gooseneck, volute, rosette). Post-to-post systems terminate the handrail between newel posts.
• WoodStairCo supplies all stair railing parts- handrails, balusters, newel posts, box newels, handrail fittings- in wood species to match your stair treads.
• Building code (IRC R311.7.8) requires stair handrails on at least one side of every staircase with four or more risers, between 34 and 38 inches above the stair nosing.

Parts of a Staircase-  The Step Components

The step assembly is the structural core of the staircase- the parts you stand on and that carry the load.

Tread

The tread is the horizontal surface you step on. It is the most visible component of the staircase from above. Standard residential stair treads are 11-1/2 inches deep (front to back) and are made from solid hardwood, engineered wood, or other materials. WoodStairCo manufactures solid hardwood stair treads in over 31 species, in both retro (3/4-inch overlay) and traditional (1-inch full replacement) profiles.

Riser

The riser is the vertical board that closes the space between each tread. It gives the staircase a finished appearance and provides structural support. Standard residential risers are 7 to 7-3/4 inches tall. Risers can be hardwood (matching the tread species) or pre-primed white- the most popular choice in the US for the high-contrast wood-and-white staircase look.

Nosing

The front edge of the tread that extends beyond the riser is known as nosing- typically 1 to 1-1/4 inches. Nosing serves both a safety function (providing more stepping surface at the front of each step) and an aesthetic function (creating the shadow line that defines each step visually). IRC building code requires a minimum nosing projection on stairs.

Stringer

The stringer (also called a string, stringer board, or carriage) is the angled structural member that runs along the side of the staircase and supports the treads and risers. There are typically three stringers on a standard residential staircase- one on each side and one in the middle. Stringers can be closed (with a flat face) or open (notched to show the tread profile).

Skirtboard

The skirtboard is the flat board installed along the wall side of a staircase. It runs parallel to the stringer and provides a clean, finished edge between the tread/riser profile and the wall. Skirtboard is typically 3/4 inch thick by 10-3/4 inches wide. WoodStairCo manufactures prefinished skirtboard in multiple species to match stair tread orders.

Landing Tread

The landing tread (also called stair nosing) is the bullnose moulding profile that caps the leading edge of a stair landing- the top-of-stair transition from tread to landing floor. It is 5-1/4 inches wide with a groove on the back that accepts 3/4-inch flooring tongue. See the WoodStairCo Staircase Landings guide for full installation guidance.

Parts of a Stair Railing

The stair railing assembly- also called the balustrade- consists of several named components. Understanding what each part is called helps when ordering replacements, planning a remodel, or communicating with a contractor.

Handrail

The handrail is the horizontal or sloped rail that you grasp with your hand when ascending or descending the stairs. It runs along the full length of the staircase and is supported by balusters or newel posts. Building code requires handrails on at least one side of every staircase with four or more risers. Handrails must be graspable- between 1-1/4 and 2-inch diameter for round profiles, or equivalent graspable width for other profiles.

WoodStairCo offers solid and engineered wood handrails in multiple species. The rake handrail is the sloped section running along the stair flight. The level handrail connects the top of the stair to the landing or balcony.

Balusters (Spindles)

Balusters are the vertical posts that run between the handrail and the stair treads (or base rail), supporting the handrail and forming the safety barrier of the balustrade. They are also called spindles, guards, or pickets. Balusters can be wood or metal (iron). Building code requires baluster spacing of no more than 4 inches- no sphere larger than 4 inches should pass between balusters.

WoodStairCo supplies both wood balusters and iron balusters in multiple profiles and finishes.

Newel Post

The newel post is the large, structural vertical post that anchors the balustrade system at the bottom of the stairs (starting newel), top of the stairs (landing newel), and at any turns or landings in between. Unlike balusters, which are decorative, newel posts are structural- they are bolted or secured to the floor framing and carry the structural load of the entire railing system.

WoodStairCo offers turned newel posts, box newels, and half newels in wood species to match any tread order.

Base Rail (Shoe Rail)

The base rail (also called shoe rail or bottom rail) is the horizontal rail at the bottom of the balustrade system, running parallel to the stringer between newel posts. Balusters sit into the plow (groove) of the base rail in modern installation systems, rather than being drilled individually into each tread. This allows for faster installation and more consistent baluster spacing.

Balustrade

The balustrade is the complete railing assembly- handrail, balusters, newel posts, and base rail together. When someone says 'the stair railing,' they are typically referring to the balustrade. When someone says 'banister,' they may mean just the handrail, or the complete balustrade- the term is used informally for both.

Stair Railing Parts Names-  Complete Glossary

These are the named components that appear most often in stair railing specifications, contractor quotes, and product descriptions- 

 

Part Name	Definition
Volute	The spiral scroll at the bottom end of a handrail, used at the bottom of the staircase where the handrail meets a curtail or bullnose starting step. It looks like a coiled spring or snail shell.
Gooseneck	A curved handrail fitting used to transition the railing from the sloped stair angle up to the level height of a landing or balcony. Creates a smooth vertical change in handrail elevation.
Rosette	A decorative wall plate used where the handrail terminates into a wall. Provides a finished, clean end to the handrail without requiring a half-newel post.
Finial	A decorative cap placed on top of a newel post. It can be a ball, pineapple, or other decorative shape, depending on the architect of the home.
Turnout	Similar to a volute but a quarter-turn rounded end to the handrail rather than a full spiral. Used where a more subtle handrail termination is preferred over a full volute.
Easing	A curved handrail fitting that transitions the rail from the sloped rake angle to a level section. An up-easing curves upward-  a down-easing curves downward.
Rail Bolt	A double-ended bolt used to join handrail sections to handrail fittings and to newel posts in over-the-post systems. One end is threaded for wood-  the other is machine-threaded.
Plow	The groove cut along the underside of a handrail or along the top of a base rail. Square-top balusters are designed to fit into the plow for a secure, clean installation.
Half Newel	A newel post that is cut in half lengthwise and mounted flat against a wall, providing a finished appearance where the railing terminates at a wall rather than open space.
Starting Step	The first step at the bottom of a staircase, which may be wider than the field treads and have a rounded end (single turnout) or rounded ends on both sides (double turnout).
Curtail	A type of decorative starting step with a curved (crescent-shaped) rounded end, wider than standard treads. Used at the base of formal staircases.
Balcony Newel	A newel post used on an upper floor landing or balcony, at the point where the rake handrail meets the level handrail. Provides structural support for the turn.

 

Over-the-Post vs Post-to-Post Railing Systems

These two configurations define how the handrail connects to the newel posts and determine which fittings and components are required for your stair project.

Over-the-Post Systems

In an over-the-post (OTP) balustrade system, the handrail runs continuously over the top of the newel posts- the handrail is uninterrupted from bottom to top of the staircase. Handrail fittings (gooseneck, volute, easing) are required to connect the rake rail sections to each other and to the level handrail at the landing.

Over-the-post is the more traditional style and produces a flowing, continuous handrail profile. It requires more planning and more fittings but produces a cleaner architectural look. WoodStairCo's handrail fittings collection supports complete over-the-post installations in multiple species.

• Handrail is continuous from bottom to top
• Newel posts use a cap fitting- the handrail runs over the post top
• Requires-  gooseneck, volute or turnout, easings, rail bolts
• More complex to install but produces a flowing, uninterrupted rail line
• Traditional and formal staircase aesthetic

Post-to-Post Systems

In a post-to-post (PTP) balustrade system, the handrail terminates at each newel post- it runs between the posts rather than over them. The newel posts project above the handrail line, creating a visual break at each post.

Post-to-post is simpler to install and is widely used in contemporary, craftsman, and transitional staircase designs. Box newels are almost always used in post-to-post systems.

• Handrail terminates at each newel post
• Newel post tops are visible above the handrail
• Box newels are typical- the hollow square newel post
• Simpler installation- fewer fittings required
• Contemporary, craftsman, and transitional aesthetic

 

	Over-the-Post (OTP)	Post-to-Post (PTP)
Handrail path	Continuous over newel post tops	Terminates at each newel post
Newel post appearance	Cap fitting- post top is hidden under handrail	Post top is visible above handrail
Fittings required	Gooseneck, volute, easing, rail bolts	Minimal- rail connects directly to post face
Common newel type	Turned wood newel post	Box newel (hollow square post)
Install complexity	Higher- fitting calculations required	Lower- standard installation
Style	Traditional, Victorian, Colonial, formal	Contemporary, craftsman, transitional, modern

 

Railing Anatomy-  How the Parts Connect

Understanding how the components of a stair railing system connect to each other is essential for ordering the correct parts. Here is the complete hierarchy from floor to handrail top- 

• 1. The newel post is bolted or secured to the floor framing (bottom newel) or to the stringer (intermediate newels).
• 2. The base rail (if used) runs between newel posts at tread level. Balusters are glued or fastened into the plow of the base rail.
• 3. Balusters rise vertically from the tread or base rail to the handrail. Maximum 4-inch spacing required by building code.
• 4. The handrail rests on top of the balusters, sitting in the plow on the underside of the rail. It is secured to newel posts with rail bolts.
• 5. At the bottom of the staircase-  a volute or turnout transitions the rake handrail to a level or curved termination.
• 6. At the top of the staircase, a gooseneck fitting transitions the rake handrail up to the level handrail running along the landing.
• 7. Where the handrail meets a wall, a rosette or half-newel provides the termination.

In an over-the-post system, handrail fittings handle every transition point. In a post-to-post system, the serves-as-newel post is the transition point, and fittings are largely eliminated.

Stair Parts Diagram-  How to Read a Staircase Drawing

When reviewing staircase drawings, architectural plans, or contractor quotes, you will encounter both the step components and the railing components labeled together. Here is a guide to reading those diagrams- 

On a staircase elevation drawing, reading from bottom to top- 

• Bottom newel post- anchored to floor, starting point of the balustrade
• Starting step (curtail or bullnose)- first step, typically wider
• Volute or turnout- handrail termination at bottom
• Rake handrail- the sloped section running up the flight
• Balusters- typically 2–3 per tread, evenly spaced, max 4-inch gap
• Intermediate newel (if applicable)- at landing or turn
• Gooseneck- transition from rake to level handrail
• Level handrail- runs along landing or balcony
• Balcony newel- anchors upper end of railing

On a staircase plan (overhead view)- 

• Stringers- angled lines running the length of the stair flight
• Treads- horizontal rectangles (each tread is one step)
• Newel post locations- typically shown as solid squares at start, end, and turns
• Landing- flat area between flights or at top/bottom

Shop Stair Railing Parts at WoodStairCo

WoodStairCo supplies the complete range of stair railing components- handrails, wood balusters, iron balusters, newel posts, box newels, handrail fittings, and skirtboard- in species to match any stair tread order. Call (866) 283-quote on 4224 for a stair parts quote.

Frequently Asked Questions

What are the parts of a stair railing called?

The main parts of a stair railing are the handrail (the part you grip), balusters or spindles (the vertical posts supporting the handrail), and newel posts (the large anchor posts at the bottom, top, and turns of the staircase). These three components together form the balustrade. Additional parts include the base rail, gooseneck fitting, volute, rosette, and handrail fittings depending on the railing system type.

What is the anatomy of a staircase?

A staircase has two systems-  the step assembly (tread, riser, nosing, stringer, skirtboard) and the railing assembly (handrail, balusters, newel posts, balustrade). The tread is the horizontal surface you step on. The riser is the vertical board between treads. The stringer is the angled support on the side. The handrail is what you grip. Balusters support the handrail. Newel posts anchor the system at the base, top, and turns.

What are the parts of a handrail called?

A handrail system includes the rake handrail (the sloped section on the stairs), the level handrail (the horizontal section at the landing), handrail fittings (gooseneck, volute, easing, turnout) that connect the sections, rail bolts that secure fittings to the handrail, and a rosette or half-newel where the rail terminates at a wall. In over-the-post systems, the handrail runs continuously over the newel post tops.

What is railing anatomy?

Railing anatomy refers to the names and relationships of all components in a stair railing system. From bottom to top, the newel post anchors to the floor, the base rail runs between posts at tread level, balusters rise vertically into the handrail, the rake handrail runs along the stairs, handrail fittings handle transitions, and the level handrail connects to the landing. The complete assembly of these parts is called the balustrade.

What is the difference between over-the-post and post-to-post railing?

In an over-the-post railing system, the handrail runs continuously over the top of each newel post- it is uninterrupted. This requires handrail fittings (gooseneck, volute) and is the traditional formal style. In a post-to-post system, the handrail terminates at each newel post, with the post top projecting above the rail. Post-to-post is simpler to install and is the dominant style in contemporary and craftsman staircases.

What is a balustrade?

A balustrade is the complete stair railing system- the handrail, balusters, and newel posts together. It is also called the stair railing or banister (though banister technically refers only to the handrail). A balustrade provides both the safety barrier on an open staircase and the support rail for ascending and descending. Building code requires a balustrade on any staircase with an open side where a fall hazard exists.

What is a stair parts diagram?

A stair parts diagram is a labeled technical drawing that identifies each component of a staircase- tread, riser, stringer, nosing, newel post, handrail, balusters, Architects, builders, and homeowners use these diagrams, architects, builders, and homeowners to communicate stair specifications. WoodStairCo's staircase anatomy pages provide visual guides for both over-the-post and post-to-post railing systems.

What is the difference between a baluster, spindle, and banister?

These terms are often used interchangeably but have specific meanings. A baluster is the correct technical term for the vertical post that supports a handrail- also called a spindle or guard. A spindle means the same as a baluster. A banister is informal language-  it sometimes means just the handrail, sometimes the complete balustrade (handrail plus balusters), and sometimes just the balusters.