When you’re buying, building, or renovating in Perth, a building inspection is a smart first step to ensure your property is safe. But sometimes, issues come up that require deeper analysis. That’s when a structural engineer might be needed.
In this article, we’ll explain when a building inspector refers issues to a structural engineer, what’s involved in a structural engineering inspection, and what the structural engineer inspection cost typically looks like in Western Australia. Whether you’re a homeowner, investor, or first-time buyer, understanding the distinction can help you avoid costly mistakes and make better decisions.
What’s the Difference Between a Building Inspector and a Structural Engineer?
A building inspector is trained to identify a wide range of issues that may affect a property’s condition, safety, and compliance. Their inspections are broad in scope and cover roof exteriors, drainage adequacy, major and minor cracking and visual defects in masonry, concrete and paving.
However, if a concern arises that may involve the integrity of a load-bearing structure—such as the slab, footings, beams, or retaining walls—it falls outside the scope of a building inspection. That’s where a structural engineer comes in.
A structural engineer is a university-qualified, registered professional who specialises in analysing load-bearing elements. They don’t just identify issues—they perform calculations, apply Australian Standards like AS 2870 (Residential Slabs and Footings) or AS 4100 (Steel Structures), and can design solutions or sign off on repairs if required.
When is a Structural Engineer Required?
There are several situations where it’s appropriate for a structural engineer to take a detailed look at the property. These include:
1. Significant Structural Cracking
Not all cracks are cause for alarm—some are just cosmetic. But cracks that are wide, diagonal, or appear in key structural areas like load-bearing walls or slabs could be a sign of movement. A structural engineer can determine whether the cause is settlement, poor soil conditions, or inadequate construction.
The Australian Standard AS 2870 provides classification guidance for slab movement and is commonly used by engineers to assess severity and risk.
2. Slab Movement or Uneven Floors
Generally pre-purchase structural inspections by building inspectors involve visual inspections, thus footings and slabs which are below ground and not able to visible are not part of the inspection . If you suspect that your property is affected by slab heave, subsidence, or differential settlement, it is important to contact a structural engineer to assess the condition of the slab and foundations, and advise whether remedial action is required.
3. Roof Modifications or Visible Deflection
Roof structures that show signs of deflection, sagging, or alteration (for example, DIY renovations where bracing has been removed) should be reviewed by a structural engineer. These components are critical to the home’s integrity, and unauthorised changes can create safety hazards.
4. Retaining Walls or Failing External Structures
Structural engineers are often needed to assess retaining walls—especially if they are over a metre high or show signs of movement or failure. According to the Master Builders Association WA, many councils areas across WA require engineering sign-off for retaining walls over a certain height.
5. Termite Damage to Load-Bearing Timbers
If termite damage is detected in structural timbers such as wall studs, beams or roof frames, the extent of the damage may need to be reviewed by a structural engineer. They can determine if the timber can be repaired or whether structural replacement is required.
What Happens During a Structural Engineer Inspection?
Once referred, a structural engineer will carry out a site visit and perform a detailed assessment of the affected area(s). The process usually includes:
Visual inspection of structural components
Taking measurements and evaluating materials
Applying load analysis and stress calculations
Comparing findings to Australian Standards and the NCC
Providing a formal written report with findings and recommendations
Supplying certification, if required for council or legal purposes
This kind of inspection is especially useful when preparing for dispute resolution, building approvals, insurance claims, or planning rectification works.
What Does a Structural Engineer Inspection Cost?
In Perth and throughout WA, structural engineer inspection cost can vary based on the complexity of the issue and the size of the property. As a general guide:
Basic structural inspection (one issue or location): $500–$900
Full structural report (multi-point inspection or design): $1,000–$1,800
Urgent or court-ready reports: May attract higher fees depending on turnaround time and documentation required
Costs can also depend on site access, need for supporting calculations, and whether certification or design solutions are involved.
Be cautious of anyone offering structural advice without proper engineering credentials—only structural engineers registered with the Building Services Board can provide certified assessments under WA legislation.
Why Building Inspectors Refer Instead of Diagnosing
It’s important to understand that a building inspector’s role is to observe and report defects via visual appraisal (AS 4349.1 )—not to speculate or offer design advice beyond the scope of their inspection or beyond the scope of their licensing.
In Western Australia, only registered engineers can legally provide structural certifications or design assessments. This is backed by both the WA Building Services Board and Engineers Australia, who promote better clarity around engineering responsibilities through initiatives like the National Registration Framework.
If your building inspector refers you to a structural engineer, it’s not a brush-off—it’s the right thing to do to protect your safety and investment.
What to Do If You’ve Been Referred to a Structural Engineer
If your building inspector suggests further investigation, take it seriously. Prompt assessment can prevent costly long-term issues, particularly with structural movement or construction faults.
Before engaging an engineer, ensure they are:
Registered in WA (check via WA Department of Mines, Industry Regulation and Safety)
Experienced with residential properties
Able to provide a clear, written scope of work and costs
If you’re already working with Broad Building Inspections, we can help guide you to reputable, independent engineers who understand the local landscape and compliance requirements.
Final Thoughts: When to Call in a Structural Engineer
There’s a lot at stake when it comes to your property’s structural integrity. A qualified building inspector can help uncover issues early—but when something needs a deeper technical analysis, a structural engineer should be consulted.
Their expertise goes beyond identification—it provides solutions, clarity, and peace of mind. And while the structural engineer inspection cost might be an extra step in your property journey, it’s often a small price to pay for long-term protection.
If you’re in the process of building, buying, or managing a property and need a clear, unbiased building inspection—start with the basics. And if the situation calls for it, we’ll make sure you’re connected to the right experts.
Book your inspection with Broad Building Inspections today and to take the next step .