When Does Signage Require Structural Engineering?

The short answer

A structural engineer may be required when a sign:

• Is large, heavy, elevated or exposed to wind
• Is suspended above people or public areas
• Is fixed to a façade, shopfront, roof, slab or existing structure
• Requires posts, structural framing, base plates, footings or piers
• Contains heavy illuminated or digital components
• Is subject to a planning, building, landlord or certifier requirement
• Uses fixings into an existing structure whose capacity has not been confirmed
• Requires structural drawings, calculations, certification or installation inspections

Permit and certification requirements vary between states, councils, building surveyors, certifiers, landlords and asset owners. The project-specific requirements should be confirmed before fabrication or installation.

What does signage structural engineering cover?

The engineering scope should follow the complete structural load path. Depending on the sign and project requirements, this may include:

• Sign cabinet and internal framing
• Posts, columns and support frames
• Brackets, backing plates and connection plates
• Welds, bolts, screws and mechanical fasteners
• Anchors into concrete, masonry, steel or timber
• Base plates, footings, piers and foundations
• Suspended rods, cables and overhead supports
• Connections to the existing building
• Capacity of the supporting wall, slab, beam or roof
• Glass or other brittle components associated with the sign
• Secondary restraints or fall-protection measures where required

The limits of the assessment must be clearly stated. For example, certification may cover the sign assembly only, the sign and its mounting frame, or the complete system including the supporting building structure and foundation.

Why is the structural load path important?

The load path describes how forces travel from the sign to a stable supporting structure.

For a wall-mounted sign, the load path may extend through:

1. The sign face and cabinet
2. Internal framing
3. Brackets and connection plates
4. Bolts, welds or anchors
5. The supporting wall, beam or façade frame
6. The main building structure

A strong sign cabinet is not sufficient if its brackets, anchors or supporting wall cannot safely resist the applied forces.

Where the base-building structure is outside the signage engineer’s scope, that limitation should be recorded clearly. The sign may then be certified only to a nominated mounting interface, with the receiving structure verified separately.

Why is wind design critical for external signs?

A sign does not need to be heavy to generate significant structural forces. Its face can act as a large surface that catches the wind, producing:

• Bending
• Shear
• Uplift
• Overturning
• Sliding
• Torsion
• Forces in brackets, anchors and foundations

The wind assessment may consider:

• Site wind region
• Terrain and surrounding development
• Height above ground
• Exposure and shielding
• Sign dimensions and orientation
• Sign shape and solidity
• Distance from building edges
• Local pressure effects
• Dynamic response where relevant

Australian wind assessment commonly refers to AS/NZS 1170.2:2021, Structural design actions, Part 2: Wind actions, subject to the project and applicable regulatory requirements. Standards Australia identifies AS/NZS 1170.2:2021 as the current wind-actions standard.

Other standards may apply to structural steel, cold-formed steel, concrete, glass, aluminium, timber or anchors, depending on the materials and construction system.

Why are sign fixings often the critical element?

A sign frame may be structurally adequate while its attachment to the building remains unsafe.

The engineer needs reliable information about:

• The material receiving the fixing
• Substrate thickness and condition
• Anchor type, diameter and embedment
• Fastener spacing and edge distances
• Installation tolerances
• Existing reinforcement and concealed services
• Corrosion exposure
• Access for installation and inspection
• Whether the nominated substrate is actually structural

Architectural cladding, plasterboard, façade panels and decorative shopfront elements should not automatically be treated as structural supports. The engineer must identify a suitable structural element and establish how the sign will transfer its loads into it.

If the existing structure cannot be verified from drawings, photographs or investigation, a site inspection or further opening-up work may be required.

Building-mounted and shopfront signage

Shopfront and building-mounted signage can interact with several structural elements, including:

• Shopfront head framing
• Façade support members
• Roller-shutter support posts
• Concrete slabs and beams
• Structural steelwork
• Masonry walls
• Roof framing
• Suspended or overhead framing

Coordination is particularly important in shopping centres and commercial fitouts. The landlord, centre management or certifier may require structural drawings, calculations, design certification and inspection before the structural connections are concealed.

Where signage is attached to new shopfront framing, the frame should be assessed for the combined effects of glazing, signage, shutters and other supported elements included within the nominated scope.

Freestanding and pylon signs

Freestanding signs generally require assessment of both the above-ground structure and its foundation.

The design may need to address:

• Post or column strength
• Frame stability and bracing
• Base plates and hold-down bolts
• Footing or pier dimensions
• Soil parameters
• Overturning and sliding
• Foundation uplift
• Corrosion protection
• Drainage around the foundation
• Vehicle impact exposure where relevant
• Installation and maintenance access

Geotechnical information may be necessary for large signs, highly loaded foundations, sites with uncertain ground conditions or signs subject to significant overturning actions.

Suspended and overhead signs

Suspended signs require particular care because failure could affect people below.

The assessment may include:

• Sign weight
• Supporting rods, cables or frames
• Connection to the overhead structure
• Primary and secondary restraints
• Vibration or movement
• Redundancy
• Access for installation and inspection
• Capacity of the slab, beam or roof framing above

A suspended ceiling grid should not be assumed to provide structural support unless the particular system has been designed and verified for the applied load.

Example of a clearly defined signage scope

L’Everest Consulting assessed a specialist backlit sign assembly based on the manufacturer’s drawings and nominated design criteria.

The engineering scope included:

• Internal structural components of the sign
• Sign cabinet and framing
• Connections within the assembly
• Structural load path to the nominated mounting interface

The external supporting steelwork and tunnel structure were excluded for separate verification.

This scope boundary was important because it identified exactly what was being assessed and prevented the sign-assembly certification from being incorrectly interpreted as certification of the supporting structure.

Does every sign require a building permit?

Not every sign requires the same approval pathway.

Requirements can depend on:

• Sign dimensions and height
• Whether it is freestanding or building-mounted
• Its proximity to a street or property boundary
• Planning overlays and local controls
• Whether the supporting building is being altered
• Public safety considerations
• The conditions imposed by a landlord, council, certifier or asset owner

In Victoria, some Class 10b sign structures may qualify for a building-permit exemption when specified limits are satisfied. Exempt work must still resist applicable structural actions and must not adversely affect the building to which it is attached. Victorian guidance describes sign-structure exemptions and continuing structural obligations.

Planning and building permits are separate processes. The relevant council can advise on planning requirements, while a registered building surveyor determines the building-permit pathway in Victoria. Consumer Affairs Victoria provides general guidance on planning and building permits.

In NSW, development consent conditions, certifiers and asset owners may require structural drawings and certification by a suitably qualified practising structural engineer. Published NSW consent conditions provide examples of structural-engineering requirements applying to significant signage. View an example through the NSW Planning Portal.

Project-specific advice should always be obtained before fabrication or installation begins.

What information should be given to the engineer?

Providing complete information early can reduce delays and design revisions.

The initial package should preferably include:

• Site address
• Sign type and dimensions
• Sign weight
• Material specifications
• Fabrication drawings
• Proposed mounting location
• Architectural or shopfront drawings
• Proposed brackets, frames and fixings
• Details of the existing supporting structure
• Photographs of the installation area
• Base-building drawings where available
• Geotechnical information for freestanding signs
• Approval conditions, landlord criteria or certifier comments
• Manufacturer data for proprietary components

If important structural information is unavailable, the engineer may need to request a site inspection, further measurements, substrate testing or exploratory investigation.

What are the usual engineering stages?

Depending on the project, signage engineering may involve:

1. Review of signage, architectural and structural information
2. Confirmation of dimensions, weight and mounting arrangement
3. Assessment of wind and other relevant actions
4. Design or verification of frames, posts and connections
5. Design of anchors, base plates, footings or piers
6. Preparation of structural drawings and details
7. Design certification
8. Inspection during installation or before concealment
9. Final structural certification where required

A design certificate confirms the nominated design scope. It does not automatically confirm that the sign has been fabricated and installed in accordance with that design.

Where construction certification is required, inspections should be arranged before critical fixings, welds, reinforcement or structural connections are concealed.

Signage engineering by L’Everest Consulting

L’Everest Consulting provides structural engineering support for:

• Pylon and freestanding signs
• Building-mounted signs
• Illuminated and digital signs
• Shopfront signage and support framing
• Suspended and overhead signs
• Sign cabinets and internal frames
• Base plates, posts, footings and piers
• Brackets, welds, bolts, fasteners and anchors
• Specialist and non-standard sign assemblies
• Structural documentation and certification
• Installation inspections where included in the agreed scope

Learn more about our signage engineering services, review our professional accreditations, or view selected engineering projects.

Need structural engineering for a sign?

Send us the site address, signage drawings, dimensions, weight, proposed fixing details and photographs of the installation area. We can review the available information and advise the appropriate engineering scope.