Engineering For A Complying Development Certificate In NSW

A complying development certificate, or CDC, is a planning approval and a building approval in one. So in NSW the structural and civil engineering has to be finished before the certificate is issued. That is the big difference from a development application, where the detailed engineering comes later, at construction certificate stage.

A CDC is faster when the project fits. The time it saves on approval is spent earlier, on finished drawings.

What a CDC is

A CDC is issued by the council or a registered certifier under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008. The policy has codes for housing, for alterations, and for commercial and industrial buildings, each with fixed development standards.

There is no merit assessment. If the proposal complies with every standard in the relevant code, the certificate can be issued. If it misses one, it cannot. The project then becomes a development application.

Why the engineering comes first

The CDC is also the building approval. So before it is issued, the certifier has to be satisfied that the work complies with the National Construction Code.

That means the certifier needs the structural drawings and a design certificate. It needs the stormwater design, done to the council's rules, and a geotechnical report where the footings depend on one. There is no later stage for the engineering to catch up in. Drawings marked for DA are of no use to a CDC.

Where projects fall out of complying development

Land constraints. Complying development is not available on some land, including land with a heritage item and certain environmentally sensitive land, and flood and bushfire constraints limit it on other land.

Earthworks. The codes limit how deep the cut and fill can go and how close to a boundary it can sit. A sloping site that needs deep cuts or tall retaining walls can fall outside them for that reason alone.

One missed standard. A setback, a height or a site coverage figure even slightly over the limit sends the whole proposal to a development application.

Sydney Water. Where the work is near or over a Sydney Water asset, the building plan approval and any engineering assessment have to be resolved before the certificate is issued, as explained in [building over sewer mains in Sydney](/blog/building-over-sewer-mains-sydney-engineering-pathways).

Industrial and commercial work

On industrial and commercial work, CDCs are used for new industrial buildings and additions, warehouse alterations and internal fit-outs, wherever the site and the design fit the codes.

The engineering is the same engineering a DA project needs, just earlier. A new warehouse needs its frame, slab and footings designed, along the lines set out in [steel portal frames for warehouses](/blog/steel-portal-frames-for-warehouses). A new mezzanine needs the existing slab and footings checked for the new loads, as covered in [mezzanine floors in existing warehouses](/blog/mezzanine-floors-in-existing-warehouses). Racking, forklift loads and new openings in existing walls all need to be resolved on paper before the certificate exists.

What the certifier asks the engineer for

Before the CDC, the certifier wants drawings a builder can build from. It also wants a certificate saying the design complies with the National Construction Code, with the loads worked out under AS 1170 and the concrete and steel designed to AS 3600 and AS 4100.

During construction, the same inspections and certificates apply as on any other project. Footings, reinforcement and steel connections are inspected before they are covered, and the engineer certifies the work at the end, as described in [structural certification and inspection certificates in NSW](/blog/structural-certification-and-inspection-certificates-nsw).

How we approach it

The first question we ask on an industrial or alteration project is whether it is going down the CDC or the DA path, because it changes when the engineering is needed. For a CDC, we issue construction-ready drawings to the certifier at the start, not a concept set.

We also check the earthworks, retaining and boundary details against the code limits early. Finding out at the end that a retaining wall pushes the project out of complying development costs more time than the CDC was meant to save.

ACSES provides structural engineering for industrial and commercial projects across Sydney. Talk to us about a project.

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