Structural Engineer Versus Building Designer: Who Does What in WA

Western Australia’s building system asks two different professionals to solve two different problems. A building designer shapes how a home looks and functions. A structural engineer proves that the structure will stand up safely to loads, soil conditions and wind. Both roles are essential on most projects, and they interact closely with the National Construction Code and your local permit authority.

Roles at a glance

Area	Building designer	Structural engineer
Core purpose	Space planning, layouts, elevations, materials palette, documentation for permits	Structural design for footings, slabs, framing, stability and durability
Typical outputs	Concept sketches, developed plans, sections, schedules, specifications	Calculations, footing and framing plans, connection details, certification
Standards lens	Coordinates the design so it can meet the NCC and local policies	Demonstrates structural compliance with the NCC and referenced standards
Who signs what	Contributes drawings and specs that sit under the Certificate of Design Compliance	Issues structural certification often requested by councils before a permit is granted

In the WA approvals system, a registered building surveyor assesses the complete set of documents and issues the BA3 Certificate of Design Compliance, which then accompanies a BA1 certified building permit application. Engineers and designers supply the technical content needed for that certificate.

What a building designer does

A building designer is your lead for layouts, room relationships, facades, light, storage and circulation. They translate your brief into plans that respond to site orientation, setbacks, privacy and energy goals, while coordinating consultants and materials specifications.

Good designers also help clients visualise outcomes. Many provide realistic imagery alongside plans, which is especially useful when comparing façade treatments or kitchen layouts. Practices offering architectural rendering services can help you evaluate choices early, saving redraws later.

For locals, working with building designers Mandurah brings practical knowledge of canal blocks, sea breezes and corrosion-resistant material selections. Designers then liaise with your engineer so spans, wall thicknesses and footing depths line up with budget and buildability.

What a structural engineer does

The structural engineer analyses loads, soil data and wind classifications to design a structure that complies with the NCC’s performance requirements. On a typical home, that covers slab design, footings, beams and lintels, bracing, tie-downs and connections. Engineers produce calculations and drawings and often issue a certificate that assures the permit authority the structural design meets the Building Code of Australia’s deemed-to-satisfy provisions. Some councils call this a Certificate of Structural Sufficiency.

WA has also introduced mandatory registration for building engineers in stages. From 1 July 2024, building engineers are being brought under the Building Services Board with experience and qualification thresholds set for each engineering category.

How the two plug into WA’s approvals path

Most residential projects proceed as a certified application. Your designer and engineer prepare coordinated documents. A registered building surveyor then reviews that package against the NCC and issues a BA3 Certificate of Design Compliance. You or your builder lodge the BA1 with all listed plans and certificates. The permit authority relies on those documents to issue the building permit.

When you need which professional

• New builds and large alterations: Engage both early. The designer leads planning and documentation while the engineer designs the structure. This avoids late rework when spans or window openings don’t match structural realities.

• Smaller internal changes: A designer can plan and document, then bring in an engineer only where load-bearing walls, new openings or foundations are affected.

• Site-specific risks: Clay sites, reactive soils, bushfire overlays and coastal wind zones call for early structural input, even at concept stage, because they influence footing strategy and costs.

  
  

Either way, aim for a single coordinated set of drawings and specifications that the building surveyor can certify without queries. The BA3 requires that listed documents be the ones reviewed for compliance, so keep versions tidy.

Deliverables to expect

From the designer: concept and developed designs, selection schedules, notes and the full drawing set for permits. Many firms add visual tools when it comes to new home design like 3d house design Mandurah previews to help homeowners judge massing and sunlight. From the engineer: calculation packs, structural plans and details, plus a certificate tied to the issued drawings. Together, these documents ensure compliance with the NCC and give your builder clear instructions.

Bringing it together

The best outcomes come from early, steady collaboration. Let the building designer from drafting services Mandurah translate your brief into a workable plan that suits the block and lifestyle. Let the structural engineer set the bones so the home is safe, durable and efficient to build. Tie the documents together under a BA3 Certificate of Design Compliance and submit a clean BA1 pack to your council. It sounds procedural because it is, yet it is also the surest way to move from ideas to a permit without detours. If you want to see options side by side before you commit, many studios can produce photoreal visuals as part of their service mix, which is where architectural rendering services shine.