Ornamental and Architectural Metals

Ornamental and Architectural Metals

Introduction to the Trade

The ornamental and architectural metals chapter covers the installation, assembly, and fastening of non-structural metal elements that complete a building: stairs, guardrails, handrails, grilles, trellises, decorative panels, thresholds, frames, and other visible components. For the Red Seal exam, you must master the materials, fastening methods, installation tolerances, Canadian standards requirements, and applicable load calculations.

This trade differs from structural work in the importance placed on aesthetics, finishes, and tight tolerances. Ornamental work requires precision to the millimetre, whereas structural work allows for greater deviations.

Materials Used

Carbon Steel

Carbon steel is the most common material for interior ornamental elements. It is specified according to CSA G40.20/G40.21 for shapes and plates. Common grades include:

Steel exposed to the elements must be protected by galvanizing or a suitable paint system. For interior elements, a rust-inhibitive primer is often sufficient.

Stainless Steel

Stainless steel is used for visible applications where corrosion resistance is essential: handrails in public buildings, exterior ramps, exposed fasteners. Common grades are:

Stainless steel must never be in direct contact with carbon steel in the presence of moisture — galvanic corrosion would quickly destroy the carbon steel element. Electrical isolation (neoprene washer, sleeve) is mandatory.

Aluminum

Aluminum is lightweight, corrosion-resistant, and easy to extrude. Common alloys are:

Aluminum must not be in direct contact with copper, brass, or galvanized steel in the presence of moisture — galvanic corrosion is severe. Use isolators or stainless steel fasteners.

Bronze and Brass

Bronze (copper-tin alloy) and brass (copper-zinc) are used for high-end decorative elements: plates, letters, handles, ornaments. They are welded using the TIG process with a filler rod of the same composition. Bronze naturally patinas over time — a lacquered finish can be applied to preserve the original appearance.

Reading Drawings and Specifications

Symbols and Notations

Architectural and structural drawings use standardized symbols. For ornamental work, pay attention to:

Specifications are organized according to the MasterFormat system from the National Master Specification Guide. Relevant sections for ornamental work are:

Dimensional Tolerances

Tolerances for ornamental elements are tighter than for structural work. Typical values are:

Metal Stairs

Terminology

Stair Calculations

The fundamental relationship for a comfortable and compliant stair:

2 × riser height + run = 630 mm (Blondel's formula)

Maximum and minimum values according to the National Building Code of Canada (NBC):

Calculation example: Total height to overcome: 3000 mm. Chosen riser: 166.7 mm (3000 ÷ 18). Run = 630 − (2 × 166.7) = 296.6 mm. Verification: 2 × 166.7 + 296.6 = 630 mm. ✓

Calculating Stringer Length

The actual stringer length is calculated using the Pythagorean theorem:

L = √(H² + G²)

Where H = total height and G = total run (number of runs × unit run).

Example: H = 3000 mm, G = 17 × 296.6 = 5042 mm

L = √(3000² + 5042²) = √(9 000 000 + 25 421 764) = √34 421 764 = 5867 mm

Add 150 to 200 mm for end supports.

Stair Assembly

Treads are fastened to stringers by:

Bolts must be ASTM A325 or A490 grade for structural assemblies, or ASTM A307 for light-duty use. Tighten to the specified torque — a bolt over-tightened can shear, too loose can work loose.

Guardrails and Handrails

NBC Requirements

The National Building Code of Canada (NBC 2015, amended) requires:

Deflection Calculation

The maximum allowable deflection for a guardrail under load is 25 mm. For a simply supported beam:

Δ = (5 × w × L⁴) / (384 × E × I)

Where:

Example: Guardrail in 50 × 50 × 3 mm square tube, 2 m span, 0.75 kN/m load.

I for hollow square tube = (50⁴ − 44⁴) / 12 = (6 250 000 − 3 748 096) / 12 = 208 492 mm⁴

w = 0.75 N/mm

Δ = (5 × 0.75 × 2000⁴) / (384 × 200 000 × 208 492) = (5 × 0.75 × 16 × 10¹²) / (1.6 × 10¹³) = 60 × 10¹² / 1.6 × 10¹³ = 3.75 mm ✓

The deflection is well below 25 mm — the section is acceptable.

Guardrail Fastening

Common fastening methods:

For chemical anchors, respect the manufacturer's curing times — ambient temperature affects setting time. At 10 °C, the time can double compared to 20 °C.

Grilles, Trellises, and Decorative Panels

Types of Grilles

Panel Fastening

Decorative panels are fastened by:

Exterior panels must allow for thermal expansion. Steel expands at 0.012 mm/m/°C. For a 3 m panel with a 60 °C temperature differential:

ΔL = 0.012 × 3 × 60 = 2.16 mm

Allow expansion gaps of at least 3 mm for this case.

Thresholds and Door Frames

Metal Thresholds

Aluminum or stainless steel thresholds are installed:

The threshold must be level (± 3 mm) and flush with the finished floor. For exterior doors, the threshold must have a minimum 2% drainage slope toward the exterior.

Metal Door Frames

Steel door frames are installed two ways:

Frames must be square (± 3 mm tolerance on the diagonal) and level. Fastening is done by:

Welding Ornamental Metals

Appropriate Processes

Weld Finishing

For visible ornamental elements, welds must be:

For stainless steel, the welded zone must be passivated after welding to restore the protective oxide layer. Use a passivation solution or pickling acid, then rinse thoroughly.

Load and Strength Calculations

Loads on Ornamental Elements

The NBC requires:

Handrail Verification

Example: Handrail in 42 mm Ø round tube, 3 mm wall thickness, mounted on supports spaced 1.5 m apart. 0.9 kN concentrated load at centre.

Maximum moment: M = P × L / 4 = 900 × 1500 / 4 = 337 500 N·mm

Section modulus of the tube: S = π × (D⁴ − d⁴) / (32 × D) = π × (42⁴ − 36⁴) / (32 × 42) = π × (3 111 696 − 1 679 616) / 1344 = π × 1 432 080 / 1344 = 3348 mm³

Stress: σ = M / S = 337 500 / 3348 = 100.8 MPa

For a 44W steel (yield strength 300 MPa), the safety factor is 300 / 100.8 = 2.98 ✓

Applicable Standards and Codes

Reference Canadian Standards

Canadian Electrical Code, Part I

When ornamental metal elements are installed near electrical circuits, the Canadian Electrical Code, Part I (CE Code) applies. Rule 8-200 requires minimum clearances between conductors and metal surfaces. Metal elements must be grounded if they are likely to be touched and are within 3 m of a conductor.

Installation Procedures

Installing a Guardrail on a Concrete Slab

Installing a Handrail on a Wall

Quality Control and Inspection

Checkpoints

Documentation

Keep mill certificates for each lot of steel. These documents attest to the chemical composition and mechanical properties. They are required during inspections.

Summary

Common Pitfalls to Avoid