What seems simple on paper can turn into a headache once walls come down and foundations get poured. Home extensions promise more space, better layout, and fresh value, but they can easily slide into long delays and budget shocks if you’re not prepared.
Getting it right starts long before builders show up. It’s about knowing how homes actually work, what councils really care about, and where costs quietly climb when you’re not looking.
Here’s how to approach a home extension like someone who’s done it before.
Get Familiar With the Structure You Already Have
Every home has limits, and ignoring them is where many extensions go wrong. Before drawing up designs, you need a full understanding of the existing structure. That means more than just knowing where the walls are.
You should look at the type of construction, the foundation depth, roofline complexity, and any quirks from past renovations. For example, older homes may look solid but hide patchy framing or outdated wiring. Others may have been built with materials or methods that don’t pair well with modern additions.
You also want to look at orientation. Where does the sun hit during the day? Will a new build at the back block natural light in the original rooms? Will a second storey cast a shadow over your neighbour’s yard and trigger objections? These things matter, and ignoring them can mean paying twice to fix problems that never should have been there.
Access is another one that people skip over. If you’re on a tight block or your home backs onto a laneway, getting materials in and out could become a logistical puzzle that costs extra time and money.
Choose Materials That Do More Than Look Good
There’s no shortage of inspiration when it comes to external finishes, but the best material for your extension isn’t just about what looks nice on Instagram. It’s about how it weathers, how it performs, how much it costs to maintain, and how it blends with what’s already there.
Weatherboards remain a common choice for a reason. They’re lightweight, versatile, and suit a range of styles. One option that stands out is HardiePlank Perth, a fibre cement weatherboard that delivers a classic timber look without the downsides of rotting or repainting every few years. It’s a smart middle ground: durable, low-fuss, and visually timeless.
When choosing materials, think long-term. Will it need sealing every few years? Is it prone to warping? Does it come with decent insulation, or will you be stuck adding layers to meet code? These questions often go unasked until it’s too late.
Planning Approval Isn’t Just a Box to Tick
Many people assume they’ll get council approval just because they’ve seen similar builds nearby. That’s rarely how it works. Local rules can be surprisingly specific, and even slight design choices might trigger a knockback.
Some councils are strict about boundary setbacks. Others care more about overshadowing or privacy for neighbouring properties. And if your home is in a heritage zone, even the colour of the external cladding could be up for debate.
You’ll need a detailed look at planning overlays, restrictions on height or floor area, and possibly even impact reports. Don’t rely on generic advice or outdated information — rules can change, and councils often interpret them differently depending on the site.
Even if you’re using a designer or builder, make sure they’re familiar with your specific council. A well-drawn plan that fails planning is just a waste of time.
Ground or Up? Choose the Right Extension Type for the Property
The idea of “adding more space” usually falls into one of two categories — extending out, or building up. Both come with pros and cons, but not every home is suited to both.
Ground-level extensions work well on larger blocks. They’re often cheaper to build, easier to access, and allow for a smooth flow between new and old areas. You can open up living zones, create better backyard access, or finally get that north-facing kitchen. But they do take up garden space, and depending on the block slope or drainage, groundwork might be more complex than expected.
Second-storey additions are more common when space is tight. They’re ideal for keeping the yard intact and separating bedrooms from living areas. But building up isn’t just stacking rooms on top. You need to think about load-bearing walls, stair placement, and structural reinforcement. These all add cost. Plus, you’re likely to face tougher scrutiny from the council and neighbours.
The best choice depends entirely on your block, your lifestyle, and what kind of changes make the most difference to how you live.
Think About Flow, Not Just Floor Area
A bigger house isn’t automatically a better house. Where many extensions fall short is in the layout: rooms that don’t connect, living spaces that feel cut off, and dark corridors that make the new part feel like an afterthought.
Good design is about movement. When someone walks from the original hallway into the new space, does it feel like the same house? Are the floors level? Are ceiling heights consistent? Does light carry through naturally?
These aren’t details you fix with a throw rug and some paint. They come from planning.
Architectural features like skylights, highlight windows, wide internal openings, and consistent flooring choices all help with flow. But they need to be built into the design from the start, not treated as quick fixes at the end.
Build It Right, Live in It Better
A great extension is about more than size or surface finishes. It’s about improving how your home works and how it feels to live in. That means asking the right questions early, making smart material choices, planning for the messy parts, and staying flexible when things shift!