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CAN CSA S37-18 (2019) – Design and Maintenance of Antenna-Supporting Structures: A Comprehensive Technical Overview
Understanding the requirements for antennas, towers, and supporting structures under the Canadian Standard
1. Scope and Application
CAN CSA S37-18 (2019) is the second edition of the Canadian standard for Antennas, Towers, and Antenna-Supporting Structures, superseding the 2013 edition. It establishes technical requirements for the design, fabrication, erection, and maintenance of new and existing structures that support antennas used in telecommunications, broadcasting, and other radio services. The standard applies to self-supporting lattice towers, guyed masts, monopoles, roof-mounted frames, and other supporting structures.
The standard does not apply to building structures, transmission line towers, or utility poles, except when antenna-supporting attachments are covered by specific clauses. It is intended for use with the National Building Code of Canada (NBC) and referenced material standards such as CSA S16 (steel structures) and CSA A23.3 (concrete design).
2. Technical Requirements
2.1 Design Philosophy and Limit States
The standard adopts a limit states design (LSD) approach consistent with the NBC. Structures must satisfy strength, serviceability, and fatigue limit states under the specified loads. Three importance categories are defined—Normal, High, and Essential—depending on the function of the facility, with corresponding load and deflection criteria.
2.2 Loads and Load Combinations
Loads considered include dead, live (including ice, maintenance, and antenna loads), wind, earthquake, and special loads (e.g., helicopter lift points). Wind and ice loads are determined using climatic data from the NBC, with additional provisions for icing events and in-span ice shedding on guyed towers. The load factors and combinations follow the NBC format, but with specific adjustments for antenna structures, such as the inclusion of ice loads concurrent with reduced wind speeds.
| Load Type | Load Factor (LSD) | Remarks |
|---|---|---|
| Dead Load (D) | 1.25 | Self-weight + permanent equipment |
| Live Load (L) | 1.50 | Maintenance loads, ice (unfactored) |
| Wind Load (W) | 1.40 – 1.60 | Based on q50 from NBC, gust factors |
| Ice Load (I) | 1.25 | Nominal ice thickness per NBC, concurrent wind at 0.4× reference |
| Earthquake (E) | 1.00 | Usually not governing for slender towers |
2.3 Materials and Fabrication
Steel members must conform to CSA G40.21 (common structural steel) or ASTM specifications for high-strength bolting. Aluminum and stainless steel are permitted where corrosion resistance or weight reduction is critical. Connections are to be designed for axial and eccentricities, with bolted or welded details following the limits of CSA S16. The standard emphasises corrosion protection in aggressive environments, including hot-dip galvanizing, painted systems, or stainless steel in marine/industrial zones.
2.4 Foundation and Anchorage
Foundations must be designed to resist overturning, uplift, and sliding under factored loads. Reactions at tower base or guy anchor points must consider the effect of second-order (P-Δ) forces, especially for guyed structures. The standard references CSA A23.3 for concrete and geotechnical parameters, and requires verification of anchorage systems for cyclic tension (e.g., guy rods with turnbuckles).
2.5 Deflection and Serviceability
Serviceability limits include maximum angular rotation (typically 1–2° depending on antenna frequency) at the antenna mounting point and a maximum horizontal deflection under service wind (1/100 of tower height). Fatigue analysis is mandatory for dynamically sensitive structures, especially those subject to vortex shedding or galloping.
3. Implementation Highlights
3.1 Erection and Construction
The standard requires an erection plan that considers temporary stability, crane loads, and worker safety. Guyed towers need pre-tensioning schedules and initial measurement of guy tensions. The designer must provide a manual for the owner, specifying inspection intervals, tightening torques, and corrosion inspection requirements.
3.2 Inspection and Maintenance
CSA S37-18 introduces a classification system for existing structures based on their condition (e.g., good, fair, poor). Inspection intervals are linked to importance category and condition, typically every 3–5 years for Normal, and annually for Essential structures. The inspection must cover all structural members, connections, guys (if present), foundation, and corrosion damage.
Tip: Owners should incorporate a structural condition assessment within 12 months of the standard’s effective date to establish a baseline and schedule compliance with CSA S37-18.
3.3 Marking and Obstruction Lighting
Structures exceeding 90 m above ground or near airports must comply with Transport Canada obstruction marking and lighting requirements (TP 1836E). The standard includes tables of minimum night and day markings for towers, with consideration of antenna ice shedding zones.
4. Compliance and Certification
Design and modification of tower structures must be carried out by a professional engineer (P.Eng.) licensed in the province where the structure is located. The engineer shall certify that the design meets CSA S37-18 and any applicable local codes. For existing structures, the engineer may perform a structural assessment to determine if retrofit or load reduction is needed.
Warning: Non‑compliance with CSA S37-18 can expose owners to significant liability in the event of structural failure. Insurers and regulatory bodies increasingly require proof of conformity with the standard during audits.
A compliance checklist is provided in the standard covering design documentation, material certificates, inspection logs, and load verification. Municipal building departments may accept CSA S37-18 as an alternative to the NBC provisions for antenna-supporting structures, subject to supplementary review.
Good Practice: Many Canadian telecommunication providers have adopted CSA S37-18 as mandatory for both new builds and existing networks, ensuring a uniform level of safety and reliability across the industry.
Critical: Inadequate ice load assumptions remain a leading cause of tower collapse in Canada. Designers must use the most recent NBC ice data and account for ice accretion on guys and antennas as specified in Clause 6.3.3 of the standard.
Frequently Asked Questions
Q: What is the main difference between CSA S37-18 and the US standard TIA-222?
A: CSA S37-18 is aligned with Canadian climatic data and the NBC load factors, while TIA-222 uses US-based wind maps and load combinations. The inspection and maintenance requirements also differ: CSA S37-18 imposes stricter intervals for Essential towers and a more detailed condition classification system. Guyed towers are given greater emphasis in the Canadian standard due to extensive use in northern regions.
A: CSA S37-18 is aligned with Canadian climatic data and the NBC load factors, while TIA-222 uses US-based wind maps and load combinations. The inspection and maintenance requirements also differ: CSA S37-18 imposes stricter intervals for Essential towers and a more detailed condition classification system. Guyed towers are given greater emphasis in the Canadian standard due to extensive use in northern regions.
Q: Is compliance with CSA S37-18 mandatory in Canada?
A: While the NBC references CSA S37-18 for antenna-supporting structures, adoption may vary by province. However, most jurisdictions require compliance when obtaining a building permit for new towers. For existing towers, owners are legally obligated to ensure continued safety under applicable codes, and following CSA S37-18 is considered the accepted practice by courts and insurers.
A: While the NBC references CSA S37-18 for antenna-supporting structures, adoption may vary by province. However, most jurisdictions require compliance when obtaining a building permit for new towers. For existing towers, owners are legally obligated to ensure continued safety under applicable codes, and following CSA S37-18 is considered the accepted practice by courts and insurers.
Q: How often should existing towers be inspected based on CSA S37-18?
A: Inspection frequency depends on the importance category and the condition class of the structure. For Normal-importance towers in good condition, a full inspection is required every 5 years. High-importance towers require inspections every 3 years, and Essential towers annually. Towers in poor condition require immediate remedial action and more frequent monitoring.
A: Inspection frequency depends on the importance category and the condition class of the structure. For Normal-importance towers in good condition, a full inspection is required every 5 years. High-importance towers require inspections every 3 years, and Essential towers annually. Towers in poor condition require immediate remedial action and more frequent monitoring.
Q: Does the standard apply to rooftop mounts or small cell structures?
A: Yes, the scope includes roof-mounted frames and non-penetrating mounts, provided they are designed to support telecommunication antennas. The standard gives specific guidance for anchor loads on roof decks and requires interaction with the building structural system. For very small (light) structures, a simplified assessment per Annex A may be used.
A: Yes, the scope includes roof-mounted frames and non-penetrating mounts, provided they are designed to support telecommunication antennas. The standard gives specific guidance for anchor loads on roof decks and requires interaction with the building structural system. For very small (light) structures, a simplified assessment per Annex A may be used.
© 2026 – All rights reserved. This article provides general technical guidance and is not a substitute for the official standard or professional engineering advice.