Renovation Budget: How To Avoid Common Budget Blow-Outs
Building and renovating your dream home is exciting, but DEFINITELY not without its challenges... especially when you don't have a clear project roadmap.
Unexpected hiccups can throw even the most carefully laid plans off track. From surprise reno costs to supplier delays, some common building and renovation pitfalls you can avoid, and some you cannot. I'm delving into both — and most importantly, giving you practical tips on what to plan for and how to sidestep budget blow-outs when building or renovating. Ready? Let's dive into some of the home truths of #renolife…
Zephyr and Stone • Building and Renovation Tools
What To Set Aside In Your Renovation Budget
Before anything else, here's the number most people get wrong. A renovation budget isn't just the cost of the work — it's the cost of the work plus a contingency, because something will always come up. For a new build, set aside 10%. For a renovation of an older home, 15–20%.
| Project type | Contingency to set aside |
|---|---|
| New build | 10% |
| Renovation — home under 20 years old | 15% |
| Renovation — older or original home | 20% |
| Heritage or unknown condition | 20%+ |
Z+S Tip • You don't have to spend your contingency. Having it there from the outset is what sets your project up for success and helps you avoid nasty surprises. A good contingency also cushions the blow of changes or mistakes that happen during construction.
Demolition Costs
Whether you're doing a small renovation or knocking down an old home to build from scratch, demolition costs are inevitable. Set aside enough for labour, waste removal and skip hire, or you'll hit a cost overrun before the project has even started.
What you pay will vary significantly depending on the scope of works and how much debris comes out, so factor it in from the get-go and don't miss any of these:
Demolition
Rubbish removal
Skip hire
Asbestos removal
Electrical, plumbing, gas + other safety measures related to demolition
Temporary power
Tile Cloud • Bathroom Renovation Budget Costs
Orton Haus • Kitchen Renovation Budget Costs
Unavoidable Renovation Costs
Especially when renovating, you're often faced with surprises you can't do anything about… outdated wiring, hidden water damage. These are exactly what your contingency is for, and why an older home needs 20% rather than 10% — you never really know what you'll uncover, especially once you start stripping back that funky 60's wallpaper.
Here are a few of the more common surprises hiding in a home:
Structural damage: cracks in the slab, water damage, sunken footings
Termites or pest infestation
Dated or dodgy electrical wiring
Building elements that don't meet current codes and need updating to comply
Sarah Yarrow Interiors • Kitchen Renovation Budget Tips
Mandala Beach House • Building Project Budget Tips
Budget Blow-Outs Caused By Delays
It's a hard truth, but a project generally takes longer and costs more than expected #aintthatthetruth. Your budget takes a massive hit every time the timeline is pushed out, so cover each of these before you start:
Trade and product availability • Lock in tradespeople, secure start dates, and hold stock with deposits. This is critical heading into Christmas or summer, when some businesses shut their books for new orders months out.
Weather • Wet weather or extreme heat can cause delays, while severe weather events can cause structural damage and unexpected repairs. It can also mean extending your lease if the project isn't finished on time. Building insurance, or a contract with contingencies, helps in extreme cases.
Changing your mind • Changes to your design or finishes will hold things up, especially if something has to be moved or reworked on site. It frustrates your builder too, because it causes stop-starts and delays. You avoid it by having your design and specifications thoroughly planned with detailed drawings from the get-go. Engaging an interior designer for cabinetry plans, colours, samples and detailed drawings often costs less than the changes and mistakes do.
Budgeting before you begin • Guesstimating is not a budgeting plan. You might feel like you can wing it, but trust me, costs differ greatly between projects — depending on your finish specification and room designs. An accurate budget plan doesn't just prevent delays, it reduces stress. It's exactly why I built my Renovation Cost Calculator and Budget Tracker — every line item, your contingency built in, and a running total that updates as the quotes come in. You'll know what you can afford and how everything affects your bottom-line in an instant.
Kate Lawrence Interiors • Building and Renovating Project Budget Tips
Noa By The Beach • Building and Renovating Project Budget Tips
Renovation Furniture Budget
When you're envisioning your dream home, it's common to overlook furniture completely amidst all the excitement of choosing paint colours and carpet. Picture this: a spacious media room with a grand modular couch, exactly as it looks on your floor plan. What comes as a surprise is the price tag — around $4k–$10k. And if you're upgrading a 6-seater dining table to a 12-seat setting, that won't come cheap either.
Building a furniture allocation into your budget is how you stay in control. Furniture planning belongs in the design phase, not after handover.
Planning exact pieces can be tricky, since you might want to experience the space firsthand before choosing. But allocating for the furniture you know you'll need means the money is there for the pieces you have your heart set on come move-in day. If you have storage, take advantage of EOFY or Black Friday sales. Alternatively, moving in with your existing furniture may not be as satisfying, but it buys you time to choose pieces that align with your style and budget.
Z+S Tip • Don't forget delivery costs, especially when buying direct from suppliers. They accumulate quickly and can knock a real hole in your budget.
DNA of Design • Renovation Project Furniture Budget Tips
DNA of Design • Renovation Project Furniture Budget Tips
Landscaping And Finishing Touches
Landscaping and finishing touches like window furnishings take any design to the next level, and everything you've put into the project falls flat if you're looking out onto a bare fence and turf from every window.
It's tempting to leave landscaping and details like curtains until the tail end. Here's a friendly word of advice: don't. Landscaping takes time to mature and settle in, so starting early is what gives you a lush, inviting outdoor space by the time you move in. And curtains aren't just about how a room looks — they control light, privacy and even energy efficiency, and leaving them out of the budget sets you up for an overrun.
Deal with these sooner rather than later and the finish is far more seamless. You'll also thank yourself for costing them in from the start, because quality landscaping and window furnishings are more expensive than most people think.
Linda Scott • Exterior Landscaping Renovation Budget
Inflation And Price Rises
Anyone who built through the last few years knows how fast a budget can move. Between 2020 and 2024, the cost of building a house in Australia rose 40.8%. Plenty of people didn't finish what they started.
Things have settled, but they haven't stopped. Forecasts for 2026 sit at 5.5% on the Gold Coast, 5% in Brisbane and 4% in Sydney and Melbourne. On a $600,000 build, 5% is $30,000 — and if your project runs eighteen months, you're wearing more than one year of it.
Trade quotes are usually valid for one month. Lock in contracts, place orders and pay deposits early — a price held is money saved
Read the escalation clause in your contract. Fixed price doesn't always mean fixed, and that's where people get caught
Flooring, fittings, fixtures and furniture creep up too, so a tight timeline keeps you on track
Z+S Tip • Build a rise-and-fall allowance separately from your contingency. Your contingency is for surprises. This is for the one you can already see coming.
Blue Lagoon Residence • Exterior Facade Building Budget
Not Hiring The Right Contractor
If you've done your due diligence choosing a builder, you'll have at least three quotes — and you might be left wondering why they're all so different. A blow-out I see over and over is when contracts aren't read carefully, inclusions are missed, and a cheap or inexperienced contractor gets the job. To avoid surprises:
Make sure your contract allows for a level of finish that meets your expectations. A full schedule of finishes is what lets your builder quote accurately
Ask to see recent work, or to speak to a past client. An experienced contractor is worth every cent and often costs you less in the long run
Read your contract carefully and always ask for a detailed quote so you know exactly what's included. Check your builder is licensed, insured, and can provide the completion certificates that prove the work meets code.
The Budget Blow-Out Nobody Talks About
The blow-outs above are all costs you didn't see coming. This one is a cost you chose — extra rooms you'll hardly ever use.
A spare bedroom or a formal dining room still needs a slab, a roof, walls, windows and air conditioning. That's tens of thousands of dollars — and it's the money that would have paid for your walk-in robe, your scullery, and the appliances you really wanted.
If you're working with a tight footprint, my small house design ideas will show you how to get more out of fewer rooms.
