What is a Structural Engineer (for Structural/Beam Design, Floor Joist Design and Form 15)?

A Structural Engineer is a qualified professional responsible for designing the structural load-bearing elements of your home — including beams, joists, posts, lintels, bracing, and tie-downs. In this task, they will also provide a Form 15 (design compliance certificate) required for approval in most states before construction begins.



This design work occurs early in your project, usually after architectural drawings are finalised and before you order frames, trusses, or begin floor construction.

What does a Structural Engineer do?

Your Structural Engineer will complete works according to your agreed scope of works. Typically, they will:

  • Review your architectural drawings and site conditions
  • Design beams, posts, floor joists, bracing walls, and load paths
  • Nominate structural materials and connection details (e.g., LVL, steel)
  • Provide span tables, layout diagrams, and tie-down requirements
  • Issue a signed Form 15 (QLD) or equivalent compliance certificate
  • Liaise with your builder, frame supplier, or certifier for adjustments


They ensure your home complies with Australian structural design standards and withstands relevant live and dead loads.

Barry's Toolbox

Lock in your window and door sizes, floor levels, and roof pitch before your engineer starts — every change affects load points and span design.


And don’t forget your slab or soil report — if it’s missing, the engineer can’t accurately design your floor structure or bracing!

What Makes a Good Structural Engineer?

Look for someone who:

  • Is registered with your state authority (e.g., RPEQ, CPEng, NER)
  • Has residential experience — not just commercial work
  • Provides clear and practical beam and joist details your builder can follow
  • Communicates directly with your frame or truss supplier if needed
  • Offers quick turnaround on minor plan changes or RFIs


Bonus points if they’ve worked with your builder or designer before — familiarity = smoother collaboration.

Before You Begin: What You’ll Need Ready

To get quotes from Structural Engineers, you’ll need:

  • Finalised architectural drawings (floor plan, elevations, sections)
  • Soil report or site classification (for footing and floor design)
  • Roof pitch, window and door sizes, wall heights
  • Preferred framing materials (timber, LVL, steel, I-joist, etc.)
  • Project address and preferred delivery timeline
  • Any known constraints or site-specific loading (e.g., heavy stone benchtops, rooftop units)

Average Timeframe

For this task, Pros typically provide quotes within 3–5 business days.

When Can I Expect Quotes?

Timeframes often vary based on demand and the type of Pro you're engaging (e.g. a plumber). If additional communication or clarification is needed is needed, the quoting process may take longer.

 

Don't be alarmed if you don't receive quotes or communication from any Build Buddy Pros straight away. Some work is more complex and the Pro may need time to comprehend your documents or scope of work. Depending on the job, there may even be some work required by the Pro before they are able to quote (e.g. a site visit might be required).

 

If the average timeframe indicated here has passed, and you have not received any messages or quotes, please feel free to contact the Build Buddy Expert Guidance and Support team for an update on quoting for this task.

Frequently Asked Questions

  • What is Form 15?

    Form 15 – Compliance Certificate for Building Design or Specification is provided by a structural engineer (or other qualified designer) to certify that the design or specification of a building element complies with the relevant building standards.


    It’s often required for:

    • Structural components like slabs, footings, steel, timber framing, roof trusses
    • Bracing layouts and tie-down schedules
    • Prefabricated components designed off-site
    • Retaining walls, balconies, or load-bearing alterations

  • Do I need a Form 15 or similar for every structural element?

    No — one Form 15 typically covers the whole structural design package for that stage of works. Your certifier will guide what’s needed.

  • Can my builder do the structural design instead?

    No — only a registered engineer can legally design and certify structural elements under building codes.

How to Complete this Task?

STEP 1

Review and Adjust the Scope of Works

Timeframes may vary based on demand and the type of Pro you're engaging (e.g., a plumber). If additional communication or clarification is needed, the quoting process may take longer.

STEP 2

Confirm Required Documents Are Uploaded

Check that the following required document(s) are uploaded for this task. These are essential to proceed:

STEP 3

Update the Quality Assurance Checklist

Go to the Quality Assurance tab in this task and review the checklist. Edit any details to suit your project requirements. Being clear and upfront helps set expectations with the Pro. Updating the checklist before requesting quotes ensures everyone is aligned.

STEP 4

Request Quotes

Click the orange ‘Request Quotes’ button to start the quoting process.

STEP 5

Review the Quotes

Once you receive quotes:

  • Review each one carefully, including the payment schedule and any special terms
  • Download attached quote documents for detailed review
  • Check each Pro’s profile and read past client reviews

STEP 6

Communicate with the Pro

If needed, message or call the Pro to clarify details or negotiate terms.

STEP 7

Accept a Quote

Choose the quote that best suits your needs. Once you accept a quote, any other pending quotes will be automatically declined. An agreement will automatically be generated.

STEP 8

Complete the Tasks In Your App

New tasks will appear to guide you through this job — follow each step carefully. Make sure to use the Quality Assurance Checklist, and refer to your contract and final Scope of Works whenever needed.

NEED HELP?

Reach Out to Your Build Buddy Pro

If you have any questions or need a hand, your Build Buddy Pro is your best first contact. They’re a licensed expert in their field and can understand the ins and outs of your project. You can message them via the platform, or you can call them directly.


If you have already contacted your Build Buddy Pro and still need further assistance, the Build Buddy Expert Guidance and Support team are here to help. They will be able to guide you on your next steps or help you find answers to any questions you may have.