Miscellaneous Metals and Stairs

Module Introduction

This chapter covers the installation, assembly, and verification of miscellaneous metals and steel stairs, an essential component of the metal fabricator (structural steel erector) trade. For the Red Seal exam, you must master the requirements of the Canadian Electrical Code, Part I (CE Code) (for grounding), but especially the CSA S16 (Design of Steel Structures) and CSA A23.1 (Concrete) standards as they apply to anchors. Stairs and guardrails are governed by the National Building Code of Canada (NBC) , 2020 edition, and its amendments. This chapter prepares you to answer questions on tolerances, stringer calculations, loads, connections, and finishes.

1. Miscellaneous Metals: Definitions and Scope

Miscellaneous metals include all steel, aluminum, or alloy elements that are not part of a building's main structural frame. These include:

Stairs, stringers, treads, risers.

Guardrails, handrails, ramps.

Grilles, gratings, fixed ladders.

Pipe supports, mechanical equipment supports.

Bearing plates, anchors, anchor bolts.

Angles, channels, tubes for secondary supports.

1.1 Materials Used

Material	Reference Standard	Typical Use
Structural steel (A36, 300W)	CSA G40.20/G40.21	Stringers, beams, light columns
Stainless steel (304, 316)	ASTM A240	Exterior guardrails, corrosive environments
Aluminum (6061-T6, 6063-T5)	CSA HA117	Handrails, decorative profiles
Malleable iron	ASTM A47	Fittings, adjustable supports
Galvanized steel	ASTM A653	Ladders, exterior platforms

Exam Point: 300W is the most common steel in Canada for secondary structural elements. Its yield strength is 300 MPa. Do not confuse it with A36 (250 MPa), which is more common in the United States.

1.2 Fabrication and Installation Tolerances

Tolerances are governed by CSA S16 (fabrication chapter) and by CISC (Canadian Institute of Steel Construction) practices. Typical tolerances to memorize:

Element	Tolerance
Total length of a stringer	± 3 mm for length ≤ 6 m
Frame squareness (diagonal)	± 2 mm per metre
Vertical alignment of a guardrail	1/500 of the height
Tread deviation	± 1.5 mm
Height difference between adjacent risers	Max 3 mm

Golden Rule: Cumulative tolerance must never compromise NBC compliance. For example, if each riser varies by 3 mm, the total deviation on a 12-step stair can reach 36 mm, which is unacceptable. You must compensate by adjusting the intermediate treads.

2. Steel Stairs: Design and Calculations

2.1 Stair Geometry

The NBC (Article 9.8.4.1) imposes precise dimensions for straight stairs:

Minimum width: 900 mm (stairs serving a room), 1100 mm (main stairs).

Riser height: between 125 mm and 180 mm.

Tread depth (run): between 255 mm and 355 mm.

Maximum slope: 45° for straight stairs.

Vertical clearance: minimum 2050 mm above the line of travel.

Slope calculation formula:

Slope = arctan (riser height ÷ tread run)

Example: riser of 180 mm, tread of 280 mm → slope = arctan(180/280) = 32.7°. Compliant.

2.2 Calculating the Number of Steps

For a straight stair connecting two levels:

34.Measure the total height (H) between finished surfaces.

35.Choose a riser height (h) within the permitted range.

36.Number of risers (n) = H ÷ h, rounded up to the nearest whole number.

37.Recalculate h = H ÷ n (must remain within 125–180 mm).

38.Number of treads = n – 1 (the last step is the landing).

39.Total stair length = (n – 1) × tread run.

Exam Example: Height of 2800 mm, chosen tread run of 280 mm.

n = 2800 ÷ 175 = 16 risers (175 mm is within the range).

Treads = 15.

Length = 15 × 280 = 4200 mm.

Common Trap: Forgetting that the upper landing counts as a step. The number of risers is always one more than the number of treads.

2.3 Stringers

Stringers are the inclined load-bearing members that support the treads. Three types:

Type	Description	Use
Cut stringer	Triangular cutouts to receive treads and risers	Residential and light stairs
Rack stringer	Flat bars or angles welded to the stringer	Industrial stairs
Center stringer	Single stringer under the center of the stair	Architectural stairs

Calculating a stringer's length:

L = √(H² + L²)

Where H = total height, L = total horizontal length.

For the previous example: L = √(2800² + 4200²) = √(7,840,000 + 17,640,000) = √25,480,000 = 5048 mm.

Minimum stringer section: For a 900 mm wide stair with two stringers, each stringer must support half the load. The maximum allowable deflection is L/360 under service load.

2.4 Treads and Risers

Treads: slip-resistant steel plates (checkered, perforated, or with carborundum coating). Typical minimum thickness: 6 mm for interior use, 8 mm for exterior.

Risers: solid or open plates. Minimum thickness: 4.8 mm.

Attachment: continuous weld or bolting with minimum 12 mm bolts.

NBC Requirement (9.8.7.1): Treads must have a slip-resistant surface. Tread nosing must be rounded or beveled with a maximum radius of 10 mm.

3. Guardrails and Handrails

3.1 NBC Requirements

Guardrails are required when the level difference exceeds 600 mm (Article 9.8.8.1). Main requirements:

Parameter	Minimum Value
Guardrail height	1070 mm (measured vertically from the tread nosing or floor)
Horizontal load resistance	0.5 kN/m applied at the top
Concentrated load resistance	1.0 kN applied at any point
Spacing between balusters	100 mm maximum (to prevent passage of a 100 mm sphere)
Vertical bar resistance	0.5 kN each

Important Exception: For residential stairs with fewer than 3 risers, the minimum height is 900 mm.

3.2 Handrails

Required on both sides if the stair width exceeds 1100 mm.

Handrail height: between 865 mm and 965 mm above the tread nosing.

Diameter: between 30 mm and 43 mm (circular section) or equivalent for gripping.

Clearance between the handrail and the wall: 50 mm minimum.

The handrail must be continuous and return to the wall or end in a volute.

3.3 Calculating Load on a Guardrail

For a 3 m long guardrail with a linear load of 0.5 kN/m:

Total load = 3 m × 0.5 kN/m = 1.5 kN.

If the guardrail has 4 posts, each post receives approximately 0.375 kN (assuming uniform distribution).

Post Verification: Each post must be anchored to resist the bending moment:

M = F × h

Where F = load at the top (kN), h = post height (m).

For F = 0.375 kN and h = 1.07 m: M = 0.375 × 1.07 = 0.401 kN·m.

This moment must be transferred to the structure through chemical or mechanical anchors. Always verify the anchor capacity according to the product evaluation report (e.g., ICC-ES or CCMC).

4. Fixed Ladders

4.1 NBC Requirements (Article 9.8.9.1)

Parameter	Value
Width between rails	400 mm to 600 mm
Rung spacing	250 mm to 300 mm
Clearance behind rungs	150 mm minimum
Distance of rungs from the wall	200 mm maximum
Load on a rung	1.3 kN concentrated

4.2 Safety Cage

A safety cage is required if the ladder exceeds 3 m in height:

The cage starts at 2.2 m above the ground.

Hoops spaced at 900 mm maximum.

Vertical bars spaced at 300 mm maximum.

Cage inside diameter: 700 mm to 800 mm.

Exam Trap: The cage does NOT start at ground level. It begins at 2.2 m to allow quick access in case of a fall.

5. Anchors and Fasteners

5.1 Types of Anchors

Type	Use	Typical Capacity
Hex head anchor bolt	Cast into new concrete	Varies by diameter and depth
Expansion anchor (HST, Kwik Bolt)	Hardened concrete	5–50 kN depending on diameter
Chemical anchor (HIT-HY 270)	Cracked or uncracked concrete	10–100 kN
Lag screw	Steel, wood	2–10 kN
Welded stud (stud welding)	Steel plates on concrete	10–80 kN

5.2 Chemical Anchor Installation Rules

95.Drill to the manufacturer's prescribed diameter (tolerance ± 0.5 mm).

96.Hole cleaning: brush × 2, blow out × 2 (the 2-2-2 rule).

97.Inject the resin starting from the bottom of the hole.

98.Insert the threaded rod with slow rotation (to avoid air bubbles).

99.Curing time: respect the indicated time (typically 20–40 min at 20 °C).

100.Do not load before curing is complete.

Temperature: Below 5 °C, curing time doubles. Use products certified for low temperatures.

5.3 Anchor Bolts Cast into Concrete

Minimum diameter: 12 mm for guardrails, 16 mm for stairs.

Anchor depth: 10 × diameter (minimum).

Minimum clearance between two anchors: 5 × diameter.

Distance to the concrete edge: 7 × diameter (minimum).

Verification per CSA A23.1: Anchors must be positioned with a tolerance of ± 6 mm in plan and ± 3 mm in elevation. Use positioning templates.

6. Welding of Miscellaneous Metals

6.1 Welding Processes

Process	AWS Code	Use
SMAW (shielded metal arc)	D1.1	Field work, repairs
GMAW (MIG)	D1.1	Shop, production
FCAW (flux-cored)	D1.1	Shop, heavy thickness
GTAW (TIG)	D1.6	Stainless steel, aluminum

Red Seal Requirement: All welders must be qualified according to CSA W47.1 (steel welding) or CSA W47.2 (aluminum welding). Procedures must be qualified according to CSA W59.

6.2 Welding Symbols

You must be able to read basic symbols:

Fillet weld: triangle on the reference line.

Groove weld: straight line on the reference line.

Plug weld: circle.

Weld size: number to the left of the symbol (in mm).

Length: number to the right of the symbol.

Contour: symbol above or below (flat, convex, concave).

Example: A triangle with "6" on the left and "50" on the right means: 6 mm fillet weld leg size, 50 mm length.

6.3 Weld Defects to Avoid

Defect	Cause	Consequence
Porosity	Moisture, gas	Weakening
Lack of fusion	Poor technique	Rupture
Cold cracking	Hydrogen, stress	Brittle fracture
Undercut	Travel speed too fast	Insufficient section
Spatter	Incorrect parameters	Appearance, contamination

Quality Control: Visual inspection (VT) is mandatory for all welds. Non-destructive testing methods (UT, RT, MT) are required for primary welds per CSA W59.

7. Finishes and Corrosion Protection

7.1 Finishing Systems

Finish	Typical Thickness	Use
Alkyd paint	75–125 µm	Interior
Epoxy paint	150–250 µm	Exterior, industrial
Hot-dip galvanizing	85–150 µm	Exterior, severe exposure
Metallizing (zinc)	80–150 µm	Bridges, marine
Electrostatic powder coating	60–120 µm	Architectural, interior

7.2 Surface Preparation

According to SSPC (Steel Structures Painting Council) standards:

SSPC-SP2: Hand cleaning (wire brush).

SSPC-SP3: Power tool cleaning (grinder).

SSPC-SP6: Commercial blast cleaning (95% clean surface).

SSPC-SP10: Near-white blast cleaning (98% clean surface).

SSPC-SP11: White metal blast cleaning (100% clean surface).

Minimum Requirement: For exterior miscellaneous metals, SP6 preparation with a surface profile of 38–75 µm is required before paint application.

7.3 Galvanizing

Standard: CSA G164 (hot-dip galvanizing).

Minimum thickness: 85 µm for 6 mm thick steel.

Do not weld after galvanizing (toxic zinc oxide fumes). If necessary, grind the galvanized area and touch up with zinc-rich paint.

Ventilation holes (6 mm) must be drilled in hollow sections before galvanizing to prevent explosion.

8. Load Calculations and Verifications

8.1 Loads per the NBC

Element	Minimum Load
Stair (uniform load)	4.8 kPa
Stair (concentrated load)	4.5 kN on a 100 mm × 100 mm area
Guardrail (linear load)	0.5 kN/m
Guardrail (concentrated load)	1.0 kN
Ladder (rung)	1.3 kN

8.2 Verifying a Stair Tread

For a 6 mm thick steel tread, 280 mm wide, spanning 900 mm:

148.Uniform load: 4.8 kPa × 0.28 m = 1.34 kN/m.

149.Maximum moment: M = (w × L²) ÷ 8 = (1.34 × 0.9²) ÷ 8 = 0.136 kN·m.

150.Required section modulus: S = M ÷ (0.9 × Fy) = 136,000 N·mm ÷ (0.9 × 300 MPa) = 504 mm³.

151.Actual section modulus (6 mm plate, 280 mm wide): S = (b × h²) ÷ 6 = (280 × 36) ÷ 6 = 1680 mm³.

Conclusion: The tread is compliant (1680 > 504). High safety factor.

8.3 Verifying a Guardrail Post

Square tubular post 50 × 50 × 3 mm, height 1070 mm, concentrated load of 1.0 kN at the top:

155.Moment: M = 1.0 kN × 1.07 m = 1.07 kN·m.

156.Tube section modulus: S = (B⁴ – b⁴) ÷ (6 × B) = (50⁴ – 44⁴) ÷ (6 × 50) = (6,250,000 – 3,748,096) ÷ 300 = 8339 mm³.

157.Stress: σ = M ÷ S = 1,070,000 N·mm ÷ 8339 mm³ = 128 MPa.

158.Ratio: 128 ÷ (0.9 × 300) = 0.47 → Compliant (less than 1.0).

9. Installation and Work Sequence

9.1 Steel Stair Installation Procedure

162.Field measurements: Verify the actual dimensions of the opening (never rely on plans alone).

163.Anchor verification: Position, diameter, depth.

164.Lifting and positioning: Use appropriate slings and lifting equipment.

165.Alignment: Spirit level, plumb bob, laser level.

166.Temporary fastening: Shims, jacks, temporary attachments.

167.Final welding or bolting: Follow the welding sequence to minimize distortion.

168.Final verification: Tolerances, squareness, level.

169.Finishing: Paint touch-ups, application of slip-resistant coating.

9.2 Welding Sequence to Avoid Distortion

Weld from the center toward the ends.

Alternate sides (skip welding).

Use tack welds of 25 mm every 300 mm before continuous welding.

Allow cooling between passes.

9.3 Coordination with Other Trades

Concrete: Anchors must be placed before pouring.

Electrical: Grounding of metal guardrails must be connected according to the Canadian Electrical Code, Part I (CE Code) (Rule 8-200 for grounding of metal structures).

Plumbing: Avoid conflicts with piping in stair shafts.

10. Reference Standards and Codes

Standard	Title	Application
CSA S16	Design of Steel Structures	Design of elements
CSA W59	Welded Steel Construction	Weld quality
CSA W47.1	Certification of Steel Welding Companies	Shop certification
CSA G40.20/G40.21	Structural Quality Steels	Material specifications
CSA G164	Hot-Dip Galvanizing	Corrosion protection
NBC 2020	National Building Code of Canada	Occupancy requirements
CSA A23.1	Concrete Materials and Methods	Anchors in concrete
CISC	Institute of Steel Construction Guide	Fabrication practices

Important Note: The NBC is a model code. Each province adopts its own version, but the technical requirements are essentially identical. The Red Seal exam is based on NBC requirements.

Traps to Avoid

185.Confusing the number of treads with the number of risers: The number of risers is always one more than the number of treads. A stair with 12 treads has 13 risers.

186.Forgetting the ladder safety cage: It starts at 2.2 m from the ground, not at ground level. Many candidates answer 3 m or 0 m.

187.Using the wrong load for guardrails: The linear load is 0.5 kN/m, but the concentrated load is 1.0 kN. Both loads must be verified separately.

188.Neglecting cumulative tolerances: A tolerance of ± 3 mm per riser may seem acceptable, but over 15 risers, the total deviation can reach 45 mm, which far exceeds NBC requirements.

189.Confusing welding standards: CSA W59 is for steel structures, CSA W47.1 is for company qualification, and CSA W47.2 is for aluminum. Do not mix them up.

190.Forgetting surface preparation: Paint applied to an unprepared surface (SP2 instead of SP6) is a typical failure. SSPC-SP6 is the minimum for exterior work.

191.Calculating stringer length without accounting for tread thickness: The actual height to be climbed includes the thickness of the top tread. A calculation that is 6 mm too short can make the stair non-compliant.

192.Ignoring temperature when installing chemical anchors: Below 5 °C, curing time doubles. An anchor loaded too early can fail.

193.Not checking deflection: The maximum allowable deflection is L/360. For a 5 m stringer, the maximum deflection is 13.9 mm. Excessive deflection indicates an insufficient section.

194.Forgetting grounding requirements: Exterior metal guardrails must be grounded according to the Canadian Electrical Code, Part I (CE Code). This requirement is often forgotten in answers.

Summary

Miscellaneous metals include all secondary steel elements: stairs, guardrails, ladders, supports.

Tolerances for fabrication and installation are governed by CSA S16 and CISC practices. Typical tolerances are ± 3 mm for lengths and ± 1.5 mm for treads.

Stairs must meet NBC dimensions: risers of 125 to 180 mm, treads of 255 to 355 mm, minimum width of 900 mm.

The number of risers is calculated by dividing the total height by the chosen riser height, then rounding up.

Guardrails are required for level differences greater than 600 mm, with a height of 1070 mm and loads of 0.5 kN/m or 1.0 kN concentrated.

Fixed ladders require a safety cage beyond 3 m, starting at 2.2 m from the ground.

Chemical anchors require rigorous cleaning (2-2-2 rule) and adherence to curing times.

Welding must be performed per CSA W59 by welders qualified per CSA W47.1.

Corrosion protection finishes include paint, galvanizing, and metallizing, with surface preparation per SSPC standards.

Load calculations must verify both uniform and concentrated loads, with a safety factor of 0.9 × Fy.

Self-Assessment Questions

209.A stair has 14 risers of 175 mm and treads of 280 mm. What is the total horizontal length?

Answer: 13 × 280 = 3640 mm.

211.What is the minimum guardrail height for a residential stair with 4 risers?

Answer: 1070 mm (900 mm only for fewer than 3 risers).

213.A 1.07 m guardrail post receives a concentrated load of 1.0 kN. What is the moment at the base?

Answer: M = 1.0 × 1.07 = 1.07 kN·m.

215.What is the minimum surface preparation for a painted exterior guardrail?

Answer: SSPC-SP6 (commercial blast cleaning).

217.At what height does the safety cage of a fixed ladder begin?

Answer: 2.2 m above the ground.

219.What is the minimum diameter of an anchor bolt for a guardrail?

Answer: 12 mm.

221.What is the maximum allowable deflection for a 4.5 m stringer?

Answer: 4500 ÷ 360 = 12.5 mm.

223.What is the typical curing time of a chemical anchor at 20 °C?

Answer: 20 to 40 minutes.

225.Which standard governs the qualification of steel welders?

Answer: CSA W47.1.

227.A stair has risers of 180 mm and treads of 250 mm. Is it compliant?

Answer: Yes, 180 ≤ 180 and 250 ≥ 255 → No, the tread is less than 255 mm. Not compliant.

This chapter covers all the knowledge required for the Red Seal exam on miscellaneous metals and stairs. Review the dimension tables, calculation formulas, and NBC requirements. Good luck with your preparation!

Miscellaneous Metals and Stairs