Stair Drafting, Balustrades and Construction Details

Introduction

Stairs are three-dimensional building elements that provide safe and convenient movement between different floor levels. For a civil draftsman, stair work is not limited to drawing a plan. The drafter must communicate geometry, levels, materials, structural form, finishes, balustrades, handrails, junctions and construction tolerances through coordinated plans, elevations, sections and enlarged details.

A stair drawing must answer practical questions: Where does the flight begin and end? How many risers are provided? What are the going, rise and width? How is the stair supported? How are the balustrade and handrail fixed? How does the stair connect to the landing and floor slab? Clear drafting is therefore a form of technical coordination between architectural design, structural design and construction practice.

This chapter explains the principles and procedures used to prepare stair plans, elevations, sections and construction details for flights, landings, strings, waist slabs, treads, risers, nosings, handrails and guards. Dimensions and safety requirements must always be checked against the current building regulations, accessibility standards and structural specifications applicable to the project location.

Learning Objectives

By the end of this chapter, the learner should be able to:

1. Identify the principal parts and types of stairs.
2. Calculate risers, treads, stair pitch and overall stair dimensions.
3. Prepare a correctly dimensioned stair plan, elevation and section.
4. Draft open and closed strings, waist slabs, treads, risers and nosings.
5. Detail balustrades, guards, handrails and their connections.
6. Coordinate stair geometry with structural, architectural and safety requirements.
7. Detect common drafting errors and check a completed stair drawing.

1. Stair Terminology and Components

A flight is a continuous series of steps between two landings. A landing is a level platform at the top, bottom or change of direction of a stair. A straight stair has one uninterrupted flight, while a dog-legged stair has two parallel flights running in opposite directions, usually without a well between them. A quarter-turn stair changes direction through approximately 90°, and a half-turn stair changes direction through approximately 180°.

The principal components are as follows:

• Riser: The vertical face or vertical height between consecutive treads.
• Going: The horizontal distance from the face of one riser to the face of the next riser, measured on the walking line.
• Tread: The horizontal upper surface of a step. In some usage, tread includes the going and any projecting nosing.
• Nosing: The projecting edge of a tread beyond the face of the riser below.
• String or stringer: An inclined member supporting the ends of steps. A closed string conceals the step ends; an open string is cut or shaped to show the step profile.
• Waist slab: The inclined reinforced-concrete slab supporting steps in a slab stair.
• Soffit: The underside of the stair or waist slab.
• Pitch line: A line joining the nosings or theoretical step corners, used to establish stair inclination.
• Handrail: A graspable rail intended to assist users.
• Balustrade: The assembly of handrail, guards, posts, infill and fixings at the side of a stair or landing.
• Guard: A protective barrier preventing falls from an open side.
• Newel: A principal post at the beginning, end or turning point of a balustrade.
• Winder: A tapered step used to turn a stair without a full landing.

In drawings, terminology should be used consistently. For example, a note reading “25 mm nosing projection” should not be confused with the going, which is normally measured between riser faces.

2. Stair Geometry

2.1 Rise and Going

The stair geometry is governed primarily by the total vertical rise and the available horizontal run. Let:

• H = total floor-to-floor rise;
• R = individual riser height;
• G = individual going;
• n = number of risers;
• m = number of treads or goings in a flight.

The basic relationships are:

and, for a flight that finishes at the upper floor level,

where L is the horizontal run. In a conventional flight, the number of treads is commonly one fewer than the number of risers because the upper floor or landing forms the final walking level:

This relationship must be checked against the particular plan arrangement. Intermediate landings and changes in level can alter how the run is scheduled.

2.2 Proportion and Comfort

A commonly used preliminary comfort relationship is:

The expression is a design guide rather than a universal legal rule. It assumes ordinary walking conditions and should not replace local regulations. A second useful check is the approximate pitch angle:

where θ is the pitch angle measured from the horizontal. A stair that is too steep may be unsafe or uncomfortable, while a very shallow stair consumes excessive floor area.

Worked Example 1: Determining Riser and Going

An architectural plan requires a stair to rise 3,000 mm between finished floor levels. The designer proposes 18 equal risers and a going of 270 mm.

The riser is:

The number of goings in a straight flight ending at the upper floor is:

The horizontal run is:

The comfort value is:

Thus, the proposed arrangement has an approximate riser of 166.7 mm, a run of 4,590 mm and a comfort value of 603.4 mm. The drafter should show the calculated dimensions and obtain confirmation that the selected values comply with the governing regulations.

2.3 Setting Out the Stair

The recommended setting-out sequence is:

1. Establish the finished floor levels and the total rise.
2. Select a practical number of risers so that all risers are equal.
3. Calculate the exact riser height; do not round individual risers independently.
4. Select the going using the available space and comfort relationship.
5. Calculate the run and locate landings.
6. Check headroom, stair width, door clearances and circulation spaces.
7. Coordinate the stair with structural supports and openings.

Equal risers are essential. A small difference between adjacent risers can cause a trip because users develop a regular stepping rhythm. Finished floor thicknesses, tile build-ups and nosing finishes must therefore be included when setting out levels.

3. Stair Types and Structural Forms

3.1 Straight Flight

A straight flight is simple to set out and easy to dimension. It requires sufficient linear space and may require an intermediate landing where the rise or length exceeds regulatory limits. In plan, the flight is shown with parallel strings or edge lines, tread divisions and an up-direction arrow.

3.2 Dog-Legged Stair

A dog-legged stair has two flights parallel to one another and connected by an intermediate landing. It is economical in plan area and commonly used in residential and institutional buildings. The plan should show the width of each flight, the landing dimensions, the central wall or open well, the direction of travel and the number of risers in each flight.

3.3 Open-Well and Half-Turn Stairs

An open-well stair contains a visible gap between flights. This arrangement permits a more generous central space and may improve daylight and visual openness. The well must be dimensioned and protected where it creates a fall hazard.

3.4 Winder and Spiral Stairs

Winders are tapered steps arranged around a turn. Their goings must be checked on the walking line and at the narrow end. Spiral stairs are space-efficient but require careful control of clear width, headroom, handrail geometry and furniture movement. They should not be selected merely to solve a drafting problem; their suitability depends on use, accessibility and regulations.

3.5 Structural Arrangements

Common structural forms include:

The drafter does not design structural reinforcement unless instructed and qualified to do so. However, the drawing must reserve space for structural members and accurately represent information supplied by the structural designer.

4. Preparing the Stair Plan

A stair plan is generally drawn at the level that best reveals the arrangement, often a plan cutting through the flight at approximately handrail height or as specified by drafting convention. The plan should include:

• flight width;
• riser and tread lines;
• landing dimensions;
• strings or stair edges;
• central newel or wall where applicable;
• handrail and guard lines;
• stair opening in the floor or roof;
• up-direction arrow;
• numbering of risers where useful;
• dimensions and level references;
• door swings and nearby obstructions.

The lower portion of a flight may be drawn with visible step lines, while the upper portion beyond the plan cut may be shown with lighter or broken lines, depending on office standards. Graphic conventions must be stated in the drawing legend if they could be misunderstood.

The direction arrow should point upward toward the higher level and should be accompanied by a level notation such as “UP 17 RISERS @ 166.7” or equivalent. Avoid relying on the arrow alone when the stair is complex.

Plan Dimensioning

Dimension the clear stair width between finished faces, not merely between structural members, unless the dimension is explicitly identified as structural. Show the landing length, opening dimensions and relationship to walls. For winders, indicate the walking line and verify that the going is acceptable at that line. Avoid placing dimensions across congested tread lines; use extension lines and a clear dimension string outside the stair.

5. Preparing Elevations and Sections

5.1 Stair Elevation

A stair elevation shows the visible side profile. It may include the pitch line, riser faces, tread surfaces, strings, landing edges, balustrade posts, handrail and floor levels. Elevations are particularly useful for checking the visual rhythm of the stair and the alignment of balustrade elements.

5.2 Longitudinal Section

The longitudinal section is the primary drawing for vertical stair geometry. It should show:

• lower and upper finished floor levels;
• each riser and going or a representative stepped profile;
• waist slab or stringer;
• thickness of treads, risers and finishes;
• landing slabs and supports;
• underside and soffit;
• headroom clearance;
• handrail and guard heights;
• construction joints and bearings where required.

The finished floor datum must be used consistently. If the structural slab level differs from the finished floor level, show both levels and identify the floor build-up.

5.3 Transverse Section

A transverse section is taken across the flight. It establishes clear width, waist slab thickness, edge beams, strings, handrail positions and balustrade fixing. It is also useful for showing the relationship between a wall, a string and the stair finish.

Headroom

Headroom is measured vertically above the pitch line or walking surface, according to the governing standard. The required clearance varies with jurisdiction and building type. The drawing should show a headroom check line and a dimension to the nearest obstruction. The drafter must not assume that a stair passes simply because the plan appears clear.

6. Detailing Treads, Risers, Nosings and Strings

6.1 Treads and Risers

Treads may be formed from timber, stone, tile, concrete, steel plate or composite products. A detail should identify the tread material, thickness, support and finish. Risers may be closed, open or clad. Open risers require special safety consideration because objects or feet can pass through the opening.

A typical enlarged detail should show the tread-to-riser junction, nosing projection, finish thickness, adhesive or mechanical fixing where relevant, and the supporting string or slab. Do not draw a finish line without indicating how the finish is supported.

6.2 Nosings

The nosing should be consistent along the flight. Excessive projection can reduce the effective going and create a trip hazard. Where a contrasting strip or anti-slip insert is required, show its width, location and material. The insert should not be represented as a random thick line; it must be dimensioned or referenced to a specification.

6.3 Strings

A closed string may be a timber board, steel plate or formed concrete edge. An open string follows the stepped profile and may be timber or steel. Detail the connection between the string and the floor or landing, including bearing length, bolts, welds, brackets or anchors as appropriate.

For timber stairs, housed steps may be supported in grooves in the strings. For steel stairs, treads may be supported on angle cleats welded or bolted to stringers. For concrete stairs, the waist slab may bear on landing beams, walls or slabs. These are representative arrangements; the structural engineer’s design governs member size and connection capacity.

7. Balustrades, Guards and Handrails

A balustrade combines safety and usability. Its principal functions are to prevent falls, guide movement and provide a comfortable handhold. The drawing should distinguish between the handrail, which is grasped, and the guard, which prevents a person from falling through or over the edge.

7.1 Components

Typical components include:

• handrail;
• newel or end posts;
• intermediate posts;
• balusters or vertical bars;
• glass or solid infill;
• base shoe or side plate;
• brackets and wall returns;
• landing guard;
• end caps and transitions.

The height, opening limitations, loading requirements and climbability provisions are controlled by local regulations. The drawing should refer to the applicable standard rather than using unsupported generic dimensions.

7.2 Handrail Continuity

A handrail should generally be continuous along a flight and should return safely to a post, wall or newel where required. Sudden interruptions at landings can reduce usability. The handrail profile must be large enough to grasp and should have smooth, rounded edges. Show the handrail in plan, elevation and section, including its offset from walls and relationship to the guard.

7.3 Guard Infill and Openings

Infill may consist of vertical balusters, horizontal rails, perforated panels, mesh, glass or solid construction. Opening sizes must be checked against the applicable safety standard. Horizontal members may create a climbing risk in certain occupancies. A drafter should therefore not substitute a visually similar balustrade system without confirming compliance.

7.4 Typical Connection Details

A post may be fixed by:

1. base plate and anchor bolts to concrete;
2. side plate bolted through a steel stringer;
3. welded connection to a steel support;
4. concealed channel or shoe for laminated glass;
5. timber housing, dowels, screws or proprietary brackets.

Each detail should show the load path: handrail to posts, posts to base or string, and base to the supporting structure. Indicate bolt diameter and spacing only when supplied by the design or manufacturer. Otherwise use a reference note such as “fixing to structural engineer’s detail.”

8. Enlarged Construction Details

Enlarged details are drawn at scales such as 1:5, 1:2 or 1:1, depending on the complexity of the junction. A good detail is selective but complete: it shows the components needed to construct and inspect the junction without reproducing the entire stair.

Useful details include:

• tread, riser and nosing junction;
• stair-to-landing connection;
• waist slab bearing at floor slab;
• string-to-newel connection;
• handrail return at a wall;
• post base fixing;
• glass balustrade shoe;
• expansion or movement joint;
• transition between stair finish and landing finish.

Every detail should include material tags, dimensions, levels, section marks, fixings, finishes and references to specifications. Line weights should distinguish cut elements from surfaces seen beyond. Hidden construction should be shown only where it clarifies the assembly.

9. Drafting Workflow and Quality Control

A reliable workflow is:

1. Study the architectural, structural and services drawings.
2. Establish datums, finished floor levels and stair openings.
3. Calculate the number of risers, riser height, going and run.
4. Draw the stair plan using construction lines.
5. Project the geometry into elevation and section.
6. Add structural members and landing supports from approved information.
7. Add finishes, nosings, handrails, guards and fixings.
8. Prepare enlarged details at appropriate scales.
9. Add dimensions, notes, levels, material references and drawing symbols.
10. Perform geometric, regulatory and coordination checks.

The final check should ask:

• Are all risers equal?
• Does the stair connect exactly to both finished floor levels?
• Are treads and landings correctly counted?
• Is the direction arrow correct?
• Is the stair width clear and consistent in plan and section?
• Is headroom adequate?
• Are handrails continuous and guards shown at all open edges?
• Do posts align with structural supports?
• Are finishes and nosings coordinated at landings?
• Are sections and enlarged details referenced correctly?
• Are drawing units, scales and revision information stated?

Computer-aided drafting and building information modelling improve accuracy, but they do not replace design judgment. Parametric stair tools can automatically generate steps, yet incorrect floor levels or an inappropriate justification setting can produce a technically neat but unsafe stair. Model validation remains essential.

10. Applied Case: Dog-Legged Reinforced-Concrete Stair

The following is an illustrative diploma-level case, not a substitute for a structural or regulatory design.

Background

A two-storey educational building has a floor-to-floor rise of 3,300 mm. A dog-legged stair is required within a stair hall. The available stair width is 1,500 mm, and an intermediate landing is planned at mid-height.

Problem

Develop a preliminary geometric arrangement and identify the drawings and details required for construction documentation.

Analysis

Select 20 equal risers. The riser height is:

Divide the stair into two flights of 10 risers each. If each flight terminates at the landing or floor level, each flight has nine goings. Select a going of 270 mm, subject to regulatory confirmation. The run of each flight is:

The comfort relationship is:

The landing should be at least as long as required by the governing standard and should not reduce the clear width. The stair plan must show two parallel flights, the landing, the central wall or well, the up arrow and the stair opening. The longitudinal section must show 20 equal risers, the intermediate landing level, waist slabs and headroom. A transverse section must show the 1,500 mm clear width, edge conditions and balustrades.

Approach and Solution

The proposed drawing set consists of:

• stair plan at 1:20;
• longitudinal section at 1:20;
• transverse section at 1:20;
• tread and nosing detail at 1:5;
• waist slab and landing support detail at 1:10;
• balustrade and handrail detail at 1:5;
• post base and fixing detail at 1:2 or as required.

The drawings identify the concrete stair as a reinforced-concrete waist-slab stair, with reinforcement and support dimensions referenced to the structural drawings. The balustrade is shown fixed to the landing and stair edge without penetrating the required clear handrail zone.

Outcome

The geometric check confirms equal 165 mm risers and a 270 mm going. The comfort value is 600 mm. The arrangement fits the available direction only after the landing and wall thicknesses are included in the plan. A headroom check is added because the upper flight passes below the floor opening.

Learning Points

The case demonstrates that stair drafting is an iterative coordination task. A mathematically correct riser and going do not by themselves prove that the stair fits, has sufficient headroom, or can be structurally supported. Plan, section and enlarged details must be developed together.

11. Challenges, Limitations and Professional Practice

The most common challenges are irregular existing buildings, inaccurate surveys, conflicting floor levels, late finish changes and insufficient space for compliant landings. Renovation work is particularly demanding because walls and slabs may not be square or level. Existing conditions should be surveyed and clearly distinguished from proposed work.

Regulatory requirements vary between jurisdictions and occupancies. Requirements commonly address maximum riser, minimum going, minimum width, landing size, handrail height, guard height, opening size, slip resistance, accessibility and fire egress. These matters must be verified using current official regulations.

Safety and ethics are central to stair drafting. A drafter must not conceal uncertainty, copy an unsuitable detail without checking it, or present a preliminary sketch as an approved construction detail. Where structural capacity, fire performance or accessibility is uncertain, the issue should be referred to the responsible professional.

Digital workflows introduce additional responsibilities. BIM families should contain correct dimensions and parameters; duplicated or outdated families can propagate errors through many views. Revision control, model sharing permissions and clear issue status are therefore part of professional practice.

Contemporary Developments

Current stair documentation increasingly uses BIM, laser scanning, parametric stair objects and cloud-based coordination. Point-cloud surveys can assist with irregular existing stairs, while clash detection can identify conflicts between stair openings, ducts, beams and balustrade fixings. Digital fabrication also allows precisely cut steel strings, CNC-machined timber components and prefabricated concrete flights. Nevertheless, digital precision is valuable only when the underlying geometry, regulatory assumptions and construction information are correct.

Chapter Summary

Stair drafting requires coordinated control of geometry, structure, finishes and safety. The essential geometric variables are total rise, riser, going, number of risers and horizontal run. The relationships H = nR and L = mG provide the basis for setting out, while 2R + G is a useful preliminary comfort check subject to local requirements.

A complete stair drawing package normally includes a plan, elevation, longitudinal and transverse sections, and enlarged construction details. Plans communicate arrangement and direction; sections establish levels, headroom and support; details explain treads, nosings, strings, waist slabs, handrails, guards and fixings. Balustrades must be drafted as safety systems with a clear load path and regulatory compliance. CAD and BIM improve coordination but do not replace checking, professional judgment or consultation with structural and regulatory specialists.

Key Terms

Flight: A continuous series of steps between landings.

Landing: A level platform at the end or change of direction of a stair.

Riser: The vertical height between adjacent treads.

Going: The horizontal distance between successive riser faces.

Tread: The horizontal walking surface of a step.

Nosing: The projecting front edge of a tread.

Stringer: An inclined member supporting the steps.

Waist slab: An inclined reinforced-concrete slab supporting a stair.

Soffit: The underside surface of a stair or slab.

Pitch line: A line joining the theoretical nosing points.

Pitch angle: The angle of the stair to the horizontal.

Handrail: A graspable rail assisting users.

Balustrade: The complete protective rail assembly.

Guard: A barrier preventing falls from an open edge.

Newel: A principal balustrade post.

Winder: A tapered step used around a turn.

Headroom: Clear vertical distance above the stair or walking line.

Finished floor level: The level of the completed floor surface.

Walking line: The reference line used to assess goings, especially on curved or winding stairs.

Construction detail: An enlarged drawing explaining how components are assembled.

Review Questions

Short Answer Questions

1. Define riser, going and nosing.
2. Why must all risers in a flight be equal?
3. State the relationship between total rise, number of risers and riser height.
4. What information is primarily communicated by a longitudinal stair section?
5. Distinguish between a handrail and a guard.

Long Answer Questions

1. Explain the procedure for preparing a stair plan, including dimensioning and graphic conventions.
2. Describe the components and drafting requirements of a reinforced-concrete waist-slab stair.
3. Discuss the purpose of enlarged stair construction details and identify at least five useful details.
4. Explain the setting-out procedure for a dog-legged stair from floor levels to completed drawings.
5. Discuss how local regulations influence stair geometry, headroom, handrails and guards.

Analytical / Application Questions

1. A stair rises 2,800 mm and is designed with 17 equal risers and a 275 mm going. Calculate the riser, number of goings for a flight ending at the upper floor, horizontal run and comfort value 2R + G. State what additional checks are required before approval.
2. A proposed balustrade post is shown fixed only to a thin floor finish above a concrete slab. Analyse why this may be inadequate and propose the information that should appear in a revised connection detail.
3. A BIM stair model has equal risers but the upper tread finishes 35 mm above the intended floor level because the floor finish build-up was omitted. Explain how this error affects the drawings and describe a systematic correction procedure.

Multiple Choice Questions with Answers

Question 1

A stair rises 3,000 mm and has 18 equal risers. What is the riser height?

A. 150 mm

B. 166.7 mm

C. 180 mm

D. 200 mm

Correct Answer: B. 166.7 mm

Question 2

For a conventional flight ending at the upper floor, 20 risers will normally produce how many goings?

A. 18

B. 19

C. 20

D. 21

Correct Answer: B. 19

Question 3

Which drawing most directly establishes stair headroom and floor-to-floor geometry?

A. Roof plan

B. Longitudinal section

C. Site plan

D. Reflected ceiling plan

Correct Answer: B. Longitudinal section

Question 4

What is the principal purpose of a guard?

A. To support the waist slab

B. To provide decorative trim

C. To prevent falls from an open edge

D. To determine the stair pitch

Correct Answer: C. To prevent falls from an open edge

Question 5

If R = 165 mm and G = 270 mm, what is 2R + G?

A. 435 mm

B. 600 mm

C. 705 mm

D. 870 mm

Correct Answer: B. 600 mm

Question 6

Which component is the projecting front edge of a tread?

A. Soffit

B. Newel

C. Nosing

D. Landing

Correct Answer: C. Nosing

Question 7

What should be shown by an up-direction arrow in a stair plan?

A. The direction toward the lower floor

B. The direction toward the higher level

C. The location of the structural beam

D. The direction of drainage

Correct Answer: B. The direction toward the higher level

Question 8

Which item is most important when detailing a balustrade post connection?

A. The paint colour only

B. The load path and fixing to supporting structure

C. The ceiling height only

D. The number of floor tiles

Correct Answer: B. The load path and fixing to supporting structure

Question 9

A stair with 10 risers in each of two flights and a 270 mm going has how many goings per flight when each flight ends at a landing or floor?

A. 8

B. 9

C. 10

D. 11

Correct Answer: B. 9

Question 10

Why must finished floor build-up be considered when setting out stairs?

A. It changes the required equal level-to-level geometry

B. It eliminates the need for handrails

C. It determines the building orientation

D. It replaces structural calculations

Correct Answer: A. It changes the required equal level-to-level geometry