An extension can fix a home that no longer works for you. More space, better light, a layout that fits the way you live.
It can also go wrong in expensive ways. Most of the mistakes happen early, before anyone has picked up a hammer.
Here are seven to avoid.
1. Starting with a design, not a brief
Many people begin by collecting pictures. They find an extension they love, hand it to a designer, and say “something like this”.
The problem is that a photo shows you what something looks like, not whether it suits your home or your life.
Start with the problem you’re trying to solve. Do you need a bigger kitchen? Another bedroom? A room for working from home? Then think about how you use the house now, and how that will change.
A designer works best with a clear brief. Write down how many people live there, what’s not working, and what you’d like to be able to do that you can’t now.
What to do instead: Write a one-page brief before you speak to anyone. Include your must-haves and a budget range.
2. Leaving the planning rules until late
Every block has rules. How close you can build to the boundary. How tall the building can be. How much of the land you can cover. Whether there are overlays for heritage or flooding.
Many people don’t look at these until they have a design. Then they learn it can’t be built as drawn.
In Victoria, some projects need a planning permit before you can apply for a building permit. That adds time. If your plan breaks a rule, you may need to redesign it or apply for a variation.
What to do instead: Check your council’s planning rules before you draw anything. Ask whether your project is likely to need a planning permit. It’s a short conversation that can save months.
3. Ignoring the existing house
An extension isn’t a separate building. It has to connect to what’s already there.
That means thinking about:
• how the floor levels will line up
• whether the existing structure can support the new work
• where the old and new rooflines meet
• how plumbing, drainage and electrical work will connect
• what happens to the rooms next to the new space
A common problem is a new room that blocks light from an existing one. Another is a back door that opens into a bedroom, because nobody thought about the flow.
What to do instead: Walk through the house with your designer and talk about how the new and existing spaces will work together. Look at every room the extension touches, including the new one.
4. Skipping the site survey
You might think you know where your boundaries are. But fences are often not on the boundary, and services don’t always run where you’d expect.
Without a survey, you risk building too close to a boundary, over a sewer or drain, or on an easement. Fixing that after the fact can mean demolition.
Some services may need approval from the water authority before you build near them. Others affect where you can put footings.
What to do instead: Get a proper site survey from a licensed surveyor. It shows boundaries, levels, existing structures and services. It’s a small cost compared with fixing a mistake.
5. Budgeting only for the build
The builder’s quote isn’t the total cost. A realistic budget also includes:
• design and drawing fees
• engineering and surveyor fees
• council and permit costs
• connection and upgrade of services
• new flooring, paint, lighting and fittings
• landscaping and repairs to areas damaged during the build
• a contingency for the unexpected
Many people forget the extras and blow the budget when they appear. Others spend everything on the build and have nothing left for the finishing touches.
What to do instead: Add up every cost, including the extras. Then add a contingency of around 10 to 15 per cent. If the total is more than you can afford, reduce the scope early, not halfway through.
6. Choosing on price alone
The lowest quote is tempting. But it’s often low because something’s missing.
A cheap quote may exclude items, use low allowances for fittings, or assume a simpler job than the plans show. Then variations appear and the final cost ends up higher than a fair quote would have been.
Compare quotes line by line. Check what’s included, what’s excluded, and how changes are handled. Ask about experience with projects like yours.
Also consider how well you communicate. You’ll deal with this person for months.
What to do instead: Get at least three quotes based on the same set of plans. Ask each builder to explain the differences. Choose the best value, not the lowest number.
7. Forgetting about light, orientation and flow
A good extension feels natural. Light moves through it, rooms connect, and you don’t think about the layout.
A bad one feels awkward. Dark in the middle. Hot in summer. A long corridor to get anywhere.
Think about the sun. Where does it rise and set in relation to your house? Which rooms get morning light? Which get afternoon heat? Put the spaces you use most in the best spots.
Think about how people move through the home. Where will they walk? Is the new area easy to reach? Does it open to the garden?
What to do instead: Visit the site at different times of day. Notice where the sun falls. Share what you see with your designer.
How long it all takes
Extensions rarely move as fast as people hope. Design takes time. A planning permit, if you need one, adds more. Then come the engineering, the building permit and the wait for a builder’s start date.
Plan on months before the first day on site, not weeks. If you’re hoping to be finished by a certain date, such as Christmas or a baby’s arrival, work backwards from it and add a generous margin. Rushing the early stages is how most of the mistakes above get made.
Getting it right from the start
Most of these mistakes come down to the same cause. Decisions were made too early or too fast, without enough information.
Slow down at the planning stage. It’s the cheapest time to change your mind.
A good draftsman Melbourne homeowners can rely on will ask about your brief, check the planning rules and visit the site before drawing a line. Those questions might feel like delays, but they’re what make the plans work.
An extension is a big investment. Spend the time to get the plan right, and the build becomes much simpler.
Sources
• Building permit process – Frankston City Council
• How do I apply for a building permit? – Yarra Ranges Council