Most renovation problems are decided long before anyone picks up a tool. Budget blowouts, delays and compliance trouble nearly always trace back to choices made in the first few weeks, which is also when they are cheapest to avoid.
The seven to watch
- Budgeting the quote rather than the project
- Rushing the design stage
- Choosing on price alone
- Not understanding what permits apply
- Ignoring what the existing structure can carry
- Missing the chance to improve efficiency while walls are open
- Leaving expectations unwritten
1. Underestimating the true cost
Initial quotes cover base construction and exclude a lot that still has to be paid for. Fixtures, finishes, appliances and landscaping are the usual gaps. A kitchen quote might include cabinetry installation while listing tapware, benchtops and splashbacks as provisional sums.
Variations arrive when site conditions differ from the initial assessment, or when the design changes mid-build. Older homes regularly turn up outdated wiring, asbestos or structural weakness that has to be dealt with before work continues.
A working rule
Set aside 10 to 15% of the total budget as contingency. It covers the unforeseen without forcing you to downgrade finishes late in the project, which is where most of the disappointment comes from.
2. Rushing the design stage
Thin design work produces layout problems that only become obvious once construction starts. Moving a doorway or relocating plumbing mid-build means demolishing finished work, ordering new materials and extending the program. The same change costs a fraction of that at the drawing stage.
Proper design works out how rooms connect, where light enters and how the space takes furniture and movement. It also looks ahead, at ageing in place or at another person living in the house.
3. Choosing the cheapest quote
The lowest quote usually gets there through cheaper materials, fewer inclusions, or a compressed program that shows up in the workmanship. Builders also exclude items others include, which makes a straight price comparison misleading until you read what each one covers.
Some underquote to win the job and recover it through variations on items the owner assumed were included. Others move fast to get to the next job, which produces work that has to be put right later.
Compare scope documents, not headline numbers. A quote should specify materials, brands, installation methods, timelines, fixture allowances, and what sits with the builder versus what you supply.
If one quote is well below the others, the useful question is not why it is cheap. It is what the other quotes include that this one does not.
4. Not understanding permits and council requirements
Melbourne’s planning rules vary by suburb, zone and property type. Extensions need a building permit, and many also need a planning permit depending on setbacks, heritage overlays and the scale of the work. Starting without the right approvals risks stop-work orders, fines and in some cases an order to undo finished work.
Building permits cover structural standards, energy requirements and safety. Planning permits deal with how the work affects neighbours, streetscape and local policy. Heritage overlays add restrictions on external changes, including materials and colours.
A builder who works with these councils regularly handles submissions, responds to requests for further information and deals with planning officers directly, which avoids the delays that come from incomplete applications.
5. Ignoring the existing structure
Older homes were built to standards that differ from current ones. Foundations designed for a single storey will not carry a second one without reinforcement. A load-bearing wall you want removed may need steel and additional support. Timber frames in pre-1980s homes often lack the bracing current codes require.
A structural assessment finds this before demolition. An engineer checks foundation capacity, inspects framing and determines what reinforcement the new loads need. Dealing with it during planning avoids the mid-construction version, where work stops while a solution is designed and materials are ordered.
The expensive version of this mistake
Structural problems found during demolition stop the job for weeks while they are assessed and remediated. Occasionally they make the planned renovation unviable without reinforcement that costs more than the work it was meant to support.
6. Missing the efficiency and future-needs window
A renovation is the cheapest opportunity you will get to upgrade insulation, glazing and services, because the walls and ceilings are already open. Focusing only on layout and finishes means paying full price for that work later, as a separate project.
The same applies to infrastructure. Roof orientation and electrical capacity for solar, prewiring for an EV charger, extra circuits for a home office and data cabling are all far simpler to build in now.
Accessibility belongs in the same category. Wide doorways, step-free entries and a bathroom with room for mobility aids cost very little during construction and a great deal to retrofit. They suit ageing owners and widen the pool of buyers later.
7. Leaving expectations unwritten
Unclear expectations about timelines, inclusions and process create most construction disputes. Owners who assume a finish or a method without confirming it are disappointed when something else arrives. Builders who do not flag delays or variations leave owners guessing about status and cost.
Change requests need documenting with their cost and timeline impact. Verbal agreements turn into arguments about what was approved and at what price. Written variations setting out the change, the additional cost and the schedule effect prevent that entirely.
How to avoid all seven
- Choose a builder with documented experience on projects of similar scope, and go and look at finished work
- Invest in design and site assessment before construction starts
- Confirm which approvals apply and build the application timelines into your schedule
- Compare scope documents rather than headline prices
- Get a structural assessment before demolition, not during it
- Hold 10 to 15% contingency
- Put every variation in writing
How much contingency should I allow for a renovation?
10 to 15% of the total budget is the usual range. Older homes sit at the higher end, because wiring, asbestos and structural issues are more likely to surface once work begins.
What is a provisional sum in a building quote?
An allowance for an item that has not been chosen yet, such as tapware or tiles. If your selection costs more than the allowance, you pay the difference. Provisional sums are legitimate, but a quote carrying a lot of them is less firm than it looks.
Do I need a planning permit as well as a building permit?
Often, but not always. Building permits apply to essentially all structural work. Planning permits depend on setbacks, overlays, height and the scale of the project. Your builder or designer should confirm which apply before design work gets underway.
Can I make changes once construction has started?
Yes, but the cost rises sharply once work is in place. Anything that touches plumbing, electrical or structure is the expensive kind. Get those decisions settled during design, where changing your mind costs a redrawn plan.
Why work with JTD
JTD Carpentry & Joinery has completed renovations and extensions across Melbourne on everything from heritage homes to modern builds. That range is what makes it possible to spot the likely problems during planning rather than during demolition.
Quotes set out what is included, what is provisional and what you supply separately, with scopes that specify materials, brands and installation methods. The team manages the project from design through to completion, including council approvals and trade coordination.
A registered builder (CDB-U 64740) with 20+ years of experience across Melbourne’s eastern suburbs and the Yarra Valley.
Planning a renovation?
Talk to us before you commit to a scope. The cheapest time to find a problem is while it is still on paper.
Request a consultationor call 0411 788 018