Residential Structural Drawings Melbourne: When They Are Required and What They Cover

Residential structural drawings are the engineering documents that tell your builder, building surveyor, and council exactly how the structure of your home is to be built. Without them, your building permit application is incomplete and cannot be assessed. This post explains when they are required in Victoria, what they must show, and who can produce and certify them.

When residential structural drawings are required in Victoria

In Victoria, structural drawings are required as part of a building permit application whenever the work involves structural elements. This covers a broader range of residential projects than most homeowners realise.

• New house construction (Class 1 building)
• Rear or side extensions to an existing house
• Second storey additions
• Removal of load bearing walls with beam installation
• Carport or garage construction attached to the house (Class 10a)
• Deck or pergola above a certain height or area threshold
• Retaining walls above 1 metre in height
• Any alteration that affects the structural elements of the building

What residential structural drawings must show

A standard set of residential structural drawings for a new house or major extension includes:

• Footing plan: footing type, layout, dimensions, depth below finished ground level, and reinforcement details
• Floor framing plan: joist or bearer sizes, spans, spacing, and connection to footings or walls
• Wall framing plan: stud size, spacing, bracing wall locations, and tie-down details
• Roof framing plan: rafter sizes, ridge support, ceiling joist design, and bracing layout
• Sections: cut-through views showing the connection between footing, wall, and roof elements
• Connection details: specific details for critical junctions such as beam-to-post, post-to-footing, and wall-to-roof connections
• Specification: document covering materials (concrete strength, timber grade, steel grade), construction standards (AS 2870, AS 1684, AS 4055), and inspection requirements

For projects involving steel beams (such as load bearing wall removal), the drawings also include beam sizing calculations and connection details to AS 4100 (Steel Structures).

Structural drawings vs architectural drawings

The distinction matters for the building permit process.

The building surveyor reviews both sets of drawings as part of the permit assessment. The structural drawings are checked against the relevant Australian Standards and the NCC. A permit cannot be issued without a complete structural engineering set certified by a registered engineer.

Who can produce and certify residential structural drawings

Residential structural drawings must be prepared and certified by a registered structural engineer. In Victoria, that means a Chartered Professional Engineer (CPEng) registered with Engineers Australia, or a person holding National Engineering Registration (NER) for structural engineering, or a person holding Registered Professional Engineer of Queensland (RPEQ) status where nationally recognised.

A draftsperson, building designer, or builder cannot certify structural drawings. They can produce the drafting from the engineer's calculations and specifications, but the certification on the drawings must come from a qualified structural engineer. PBE's principal engineer holds CPEng, NER, RPEQ, and RPEV registration.

NCC Class 1 and Class 10 buildings in Victoria

The National Construction Code (NCC) classifies buildings by use and occupancy. For residential structural drawings, two classes are relevant:

Class 1a covers detached houses, and Class 1b covers boarding houses and similar multi-unit dwellings. The structural requirements are set by Part 3 of the NCC and the referenced Australian Standards. Class 1 buildings are the most common residential permit category in Victoria.

Class 10 covers structures associated with a Class 1 building but not used as a dwelling: garages, carports, sheds, decks, and similar. Class 10a covers non-habitable structures. Class 10b covers fences, signs, and retaining walls. Some Class 10 structures can use standard prescriptive solutions without engineering drawings, but once the structure exceeds the thresholds in the NCC or the building regulations, engineering input is required.

Fees for residential structural drawings in Melbourne

These fees include calculations, drawings, and the engineer's certification. They exclude the building permit fee charged by the building surveyor, the soil report, and any construction work.

Timeline from architectural plans confirmed to drawings delivered

Once the architectural plans are confirmed and a soil report is available, residential structural drawings for a standard project take 5 to 15 business days to prepare and certify. Complex projects, unusual soil conditions, or projects requiring a site visit may take longer.

The structural drawings are usually the last engineering input before the permit application is submitted. Starting the engineering process as soon as the architectural plans are close to final avoids bottlenecks in the permit timeline.

Frequently asked questions

Do I need structural drawings for a small house extension?

Yes, if the extension involves structural elements. A building permit is required for most house extensions in Victoria, and a building permit for structural work requires structural drawings certified by a registered structural engineer. The size of the extension does not exempt the project from this requirement.

Can my architect produce the structural drawings?

No. Structural drawings must be prepared and certified by a registered structural engineer. An architect can produce the architectural drawings and can coordinate with the structural engineer, but the structural drawings require an engineer's certification. These are separate professional scopes requiring different registrations.

What is a structural specification and is it always required?

A structural specification is a document that accompanies the structural drawings. It specifies the materials (concrete compressive strength, timber grade, steel grade), the Australian Standards that govern the design, and any special construction requirements. It is required for any building permit that includes structural work. Without it, the building surveyor cannot verify that the materials used will match the design assumptions.

How do I know if the soil report is required before structural drawings can be produced?

For any project with a concrete slab or strip footings, a soil report that determines the site classification under AS 2870 is required before the engineer can design the footing system. Without the site classification, the engineer cannot determine the correct footing depth, width, and reinforcement. Some engineers can work with a preliminary site classification based on local knowledge and observable site conditions, but a formal soil report is the safer approach and is typically required by the building surveyor anyway.

Can I use the same structural drawings for a future extension or renovation?

Structural drawings are project-specific. They are prepared for a specific site, specific soil conditions, and a specific building configuration. If you modify the project scope after the drawings are prepared, the engineer needs to review whether the drawings need updating. For a completely new project on the same property, new drawings are required.