House Extension Services in Brisbane

Building under a raised house is a significant project, but here’s how to tackle it step by step:

Start with a budget. Be realistic and stick to it. Let your builder know upfront so they can confirm whether your project is feasible – because let’s be honest, none of my clients have suddenly won the lotto mid-build! Prices/m2 can vary, but as a guide you should allow $4000-$5000/m2. The bigger the build, the lower the rate per square metre can be. 

Get everyone on the same page. Decide what’s non-negotiable and what’s flexible. Be sure that everyone living in the home agrees on the plan before the design process starts.

Now it’s time to speak to a building designer. We’re more cost-effective than architects and still deliver thoughtful, creative designs – just without the unnecessary frills.

The order of professionals that you require are as follows:

1. Surveyor – to map your site
2. Building designer – We’re more cost-effective than architects and deliver thoughtful, creative designs without unnecessary frills
3. Town planner – if council approval is required
4. Engineer – for structural calculations
5. Certifier – for building approvals
6. Additional consultants – for site-specific reports if needed
7. Builder – needs to see completed plans before providing quotes

Some building designers, like myself, can coordinate all these consultants for you to keep the project running smoothly. But if you’re confident and have contacts, you’re welcome to manage this part yourself.

I hope this helps! For more info, check out my answers to other FAQS.  

A building certifier is required if any part of your proposed design involves engineering. Their role is to assess and approve the plans before construction begins and then confirm, once the build is complete, that it was constructed in line with the approved proposal. The proposal includes the following:

• Site plan
• Existing and demolition floor plans
• Proposed floor plans
• Existing and demolition elevation plans
• Proposed elevation plans
• Engineering specifications and details
• Any additional site-specific reports

The certifier may also assist with or request:

• Relaxations – Required if the proposed design sits closer to a boundary than the allowable setback.
• Site coverage assessment – Needed if the dwelling exceeds the allowable site coverage percentage.
• BOS (Build Over Services) – An application to the asset owner (e.g. Brisbane City Council or Urban Utilities) if building over sewer or water infrastructure.
• BAL (Bushfire Attack Level) rating – Required for sites in bushfire-prone areas.
• Energy efficiency reports – Ensures compliance with minimum sustainability standards.

A home extension will always require engineering, as it involves making the house larger and typically affects the structure.

Internal renovations, however—where you’re not increasing the overall footprint but are instead adding or removing internal walls or windows—can be a little trickier to assess.

Generally, adding a wall won’t require an engineer, as it’s usually non-structural. But if you’re removing a wall, it’s important to confirm whether it’s load-bearing. A load-bearing wall supports the weight of the roof, ceiling, or upper floor. In that case, you’ll need an engineer to design a beam or structural solution to safely redistribute the load before the wall can be removed.

Often a builder can help identify whether a wall is load-bearing, but it’s always safest to check with an engineer.  Queenslander homes are often easier to determine whether the walls are load bearing, as where the roof changes pitch/angle there will be a wall underneath for the roof to rest on.

Once you have decided to proceed with your project it’s time to start talking to a building designer. Speaking it out with a professional can help confirm that your ideas are feasible. As a building designer, I will take note of your ideas and offer suggestions to help you achieve your goals given your site conditions, council requirements, and available budget.

Generally, no. You can add an additional bathroom or ensuite within the existing footprint of your house without the need for certification, only a plumbing permit is required. However there are exceptions to this based on site specifications. You will need to discuss these with your plumber. If you are moving any walls you will need to confirm with your builder that those walls are not load bearing. If they are load bearing and an engineer is required, that will be what triggers certification.

A pool is required to be a minimum 1.0m from the boundary.