If you're building, renovating or developing in Queensland, sooner or later your building certifier will ask for a "Form 15" or a "Form 16" — and it's easy to get them confused. To make things trickier, the old Form 16 was split into several forms a few years ago, so a lot of the advice online is now out of date.
Here's a plain-English guide from an RPEQ-registered engineering team to what each certificate actually is, who can sign it, and when your project will need one.
| Form 15 | Form 16 | Form 12 | |
|---|---|---|---|
| What it certifies | A design or specification will comply if built as stated | A stage of building work is complete and compliant | An aspect of building work is complete and compliant |
| Stage | Design (before/at approval) | During/after construction | During/after construction |
| Who signs it | An appointed competent person (e.g. an RPEQ for structural design) | The building certifier | An appointed competent person (e.g. an RPEQ inspecting an aspect) |
| Typical example | Certifying your footing, slab or beam design | Certifying a whole stage passed inspection | An engineer certifying steel reinforcement before a pour |
The key thing most people miss: when your engineer inspects something on site and certifies it, that's usually a Form 12 — not a Form 16. The Form 16 is signed by your building certifier. More on that below.
A Form 15 — Compliance Certificate for Building Design or Specification certifies that a particular design or specification will comply with the building rules if it's built as described. It sits at the design stage and is given to your building certifier to rely on when they assess your building approval.
Under Queensland law (section 10 of the Building Act 1975 and sections 73 and 77 of the Building Regulation 2021), a Form 15 is completed by an "appointed competent person" — the specialist whose design is outside the certifier's own expertise. For structural work, that means a Registered Professional Engineer of Queensland (RPEQ) with structural registration.
You'll commonly need a Form 15 to certify designs such as:
Without the required Form 15, your approval can be delayed and construction may not be able to start.
A Form 16 — Inspection Certificate certifies that a stage of building work has been inspected and complies with your building development approval. It applies during and after construction.
The important distinction: under section 53 of the Building Regulation 2021, the Form 16 is completed and signed by your building certifier (a stage is made up of several "aspects"). For a single detached house (class 1a) or a class 10 structure, only the building certifier can sign the Form 16 for the final stage.
So if someone tells you "the engineer will give you a Form 16," that's usually not quite right — read the next section.
When the Building Regulation was updated in 2021, the old Form 16 was effectively split into three:
In practice, this means your structural engineer typically provides a Form 15 (for the design) and a Form 12 (for aspects they inspect on site) — and your building certifier issues the Form 16 for the stage, relying in part on those certificates.
A building certifier must formally appoint someone as a "competent person" before that person can give design or inspection help. For structural certification, that competent person is an RPEQ registered in the structural area of practice — not every engineer, and not every RPEQ, is eligible to certify structural adequacy.
Before you engage anyone, you can verify their registration on the Board of Professional Engineers of Queensland (BPEQ) register. And note: it is an offence for a competent person to knowingly give a building certifier a false or misleading certificate — these are legal documents, not formalities.
Some common residential scenarios:
Your building certifier decides exactly which certificates your specific job needs, so it's always worth confirming early — before you're mid-build and waiting on paperwork.
QED Engineers is an RPEQ-registered structural and civil engineering practice. We provide Form 15 design compliance certificates and Form 12 aspect inspection certificates for residential and commercial projects across Brisbane and South-East Queensland — designed correctly the first time, so your approval keeps moving.
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This article is general information only and reflects Queensland building requirements at the time of writing. Forms and requirements can change — always confirm exactly what your project needs with your building certifier or the Queensland Government. QED Engineers does not issue Form 16 stage certificates; these are signed by your building certifier.
Is a Form 15 mandatory in Queensland? Where a building certifier relies on a competent person's certificate for a design or specification, it must be given in the approved form (Form 15). Whether one is required depends on your project — some designs are within the certifier's own expertise and don't need a separate Form 15. Your certifier will confirm.
Can my structural engineer sign my Form 16? Generally no. The Form 16 stage inspection certificate is signed by your building certifier. Your engineer typically provides the Form 15 (design) and, where they inspect an aspect on site, a Form 12 (aspect inspection certificate).
What's the difference between Form 12 and Form 16? A Form 12 certifies a single completed aspect of work and is signed by an appointed competent person (like an RPEQ). A Form 16 certifies a whole stage and is signed by the building certifier, who may rely on Form 12 aspect certificates.
Who can issue a structural Form 15? An RPEQ registered in the structural area of practice, appointed by your building certifier as a competent person. You can verify registration on the BPEQ register.
Do I need a Form 15 for a retaining wall? Often yes, once a wall is over your council's trigger height or supports a structure. Your certifier will advise, and your engineer certifies the design via a Form 15.
