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You almost certainly need an architect on a high-end custom home. The real question is whether you appoint that architect yourself and then tender the finished drawings, or appoint one firm to carry design and construction under a single agreement.
Choosing between an architect or design and build turns on four things: how constrained your site is, how settled your brief is, how much contract risk you want to hold, and whether the project's value sits in design ambition or delivery certainty.
ROMAAC builds under a design-and-build structure. The sections below name that model's genuine weaknesses alongside the genuine weaknesses of the separate-architect route.
Also called design-bid-build. You appoint an architect directly. They develop the brief, produce concept design, prepare any planning application, then complete the construction documentation.
The drawings then go to market. Two, three or four builders price the same documents, you select one, and you sign a building contract. Your architect is usually retained through construction to administer it, inspect progress and assess claims.
You hold two contracts and two relationships.
You appoint one firm. It carries the design, either with architects in-house or with an architect it engages and pays, then constructs the house.
You hold one contract. Design and buildability are resolved inside the same organisation, so the people detailing a junction are the people who will later build it. There is no tender period, because the builder is already appointed.
A middle route suits a lot of Melbourne projects. You engage an architect independently for design and planning, then bring a builder in early on a fee basis to advise on buildability and price while the documentation is still being drawn.
The architect stays independent and buildability advice arrives before the drawings harden, at the cost of higher fees.
For the case for architectural thinking early, see 8 Reasons to Hire an Architect Early. This piece assumes you accept it and are choosing how to organise the contracts.
This part decides what happens when the project gets difficult.
You hold a design contract and a building contract. Your architect owes you a professional duty and is registered with the Architects Registration Board of Victoria.
Your builder holds a separate registration with the Building and Plumbing Commission, which from 1 July 2025 took over the functions of the former Victorian Building Authority, Domestic Building Dispute Resolution Victoria and the domestic building insurance arm of the VMIA.
Your architect is an independent advocate. When the builder says a detail cannot be built as drawn, someone who is not the builder assesses the claim. When a progress claim arrives, someone who does not benefit from it certifies it.
The disadvantage is equally real: you sit in the gap.
If the documentation is incomplete and the builder prices what was drawn rather than what was intended, the cost of closing that gap lands on you. Neither party owns the interface between design intent and buildable detail.
Arguing about where a problem originated can take longer than fixing it.
Under design-and-build, one firm carries both obligations. There is no interface to fall through. If a detail does not work, the firm that drew it solves it at its own cost, within the contract sum.
Weigh that seriously. A single point of accountability also means no independent advocate. The party assessing whether something is a variation or a design correction is the party that would pay for the correction.
Good firms handle that honestly. Poor ones do not, and you have nobody independent in the room to tell the difference.
So either appoint an independent building consultant to review claims and inspect progress, or check the firm's track record with past clients at your level before you sign.
In Victoria, if the work involves more than one trade and is worth more than $10,000, a major domestic building contract is required before work starts. That is a legal threshold, not a formality, and it applies in both structures.
Design runs free of cost and buildability pressure early on. That is the point of it. The architect explores the site, tests options and pushes the brief without a builder in the room saying a form is expensive to construct.
On a difficult site or an original brief, that freedom generates value: a steeply falling block, a heritage overlay, a protected root zone, an awkward orientation.
The cost shows up later. A design developed without buildability input can carry details that are expensive, slow or awkward to construct, and you will not find out until the drawings are priced.
Buildability advice is present from the first sketch. Construction sequencing, trade availability, material lead times and structural implications are weighed as the design develops. Fewer surprises arrive at pricing, and fewer changes once construction starts.
The weakness is the mirror image. Design ambition is sometimes constrained by a preference for what the firm knows how to build. The effect is quiet and rarely deliberate.
A builder-led process gravitates towards details the team has executed before, because those are predictable to price and to construct. If your project depends on an unusual structural idea, an unfamiliar material or a risky spatial move, the team may talk you out of it for delivery comfort rather than because the house would be worse.
Ask the firm what it has built that it had never built before, and how that went. Our own approach is set out in Design-Led Construction: What It Means for Your Build.
Approvals sit in this stage and affect both routes equally, as our guide to building permits in Victoria sets out. Who carries them differs: your architect under the separate route, the firm under design-and-build.
Completed documentation goes to several builders, who price the same drawings and specification. You get competitive tension, independent views of what the project costs, and prices you can interrogate against each other.
If one builder's joinery number sits far above the others, that is useful information. Competitive tension on price is the single strongest argument for this route.
Three things temper it:
Under design-and-build there is no tender. Pricing develops with the design, as estimates that tighten as documentation firms up, converting to a contract sum at a defined point.
That is faster, and it lets you make cost decisions while they are cheap, when a change is a line on a drawing rather than work already priced.
The weakness is equally clear. You lose competitive tension. You are relying on one firm's pricing being fair, with no second number to test it against. Three ways to manage that:
If a firm resists all three, treat that as information.
On a complex custom build, the question is not whether an unexpected condition appears but how quickly it gets resolved and who pays.
Under the separate-architect route, a problem runs builder to architect to owner and back. The architect assesses whether it is a design issue, a site condition or a construction issue, and advises you.
That assessment is independent, which is valuable. It is also slower, and where the answer is contested the two contracts pull in opposite directions. The builder has a commercial interest in calling it a design issue, the architect a professional interest in calling it a construction issue. You are between them.
Under design-and-build, resolution is usually faster because the decision sits inside one organisation and nobody argues about whose problem it is. The trade-off is the one named earlier: nobody independent is checking whether the solution is right or the cost fair.
In Victoria, most variations to a domestic building contract require a variation notice signed by both parties. The exemption is narrow. It applies only where the owner requested the change and the builder reasonably believes it will not require a permit change, will not cause delay, and will add no more than 2 per cent to the original contract price.
Every other change is a documented, signed, priced event. That forces changes into the open, which works in your favour. It also means incomplete documentation converts directly into a stream of variation notices, each a negotiation and a delay.
Neither route guarantees complete documentation. A well-run separate-architect process produces excellent drawings. A rushed design-and-build that starts on site half resolved produces poor ones. The discipline matters more than the structure.
Under the separate-architect route you get an early estimate, then a real number only when tenders come back. It arrives late, after months and a meaningful sum in design fees, and often above expectations.
You then choose between cutting scope from a design you have grown attached to and raising your budget.
Under design-and-build, cost feedback is continuous but the number stays soft for longer. You know roughly where you are early, which allows cheap adjustments. What you do not get is an independently tested number.
Two mechanisms are where cost certainty is quietly lost.
Prime cost items are items not specified or priced at contract time, such as tapware, tiles or appliances. An allowance sits in the contract and the real cost is reconciled later.
Provisional sums are estimates for work whose cost cannot be determined at contract time. The Building and Plumbing Commission's guidance is blunt: "Provisional sums should be avoided where possible as they can lead to unexpected costs."
A contract with a long list of both is not a fixed price. It is an estimate wearing a contract's clothing.
Compare the length of those lists as carefully as the headline number. It is the most useful check a non-expert client can make on cost certainty.
In Victoria, cost escalation or rise and fall clauses are prohibited unless the contract price is more than $500,000 and the Director of Consumer Affairs Victoria approves the clause. Consumer Affairs Victoria states plainly: "The director has not yet approved any cost escalation clauses."
The contract price is therefore effectively fixed and the builder carries material and labour cost movement. That applies under both routes, and it explains why builders price contingency in.
From 1 July 2026, Home Warranty insurance is required for eligible domestic building work valued over $20,000, with maximum cover of $400,000 per home. That applies in either structure.
Work through these honestly rather than choosing the structure that sounds more comfortable.
Your site is complex enough to want independent design leadership, but you also want buildability and cost tested before the documentation hardens. It costs more in fees and suits larger projects.
Demolition, service disconnection and site-condition questions sit outside the design contract, and how they are handled differs by route. Our knockdown rebuild process guide sets out that sequence.
The best test of any firm or architect is how they answer an uncomfortable question. Ask a design-and-build firm what it is worse at than an independent architect. Ask an architect what happens to your budget if tenders come back high.
Usually yes, though the architect is engaged and paid by the firm rather than by you. Some firms employ registered architects in-house, others contract an external practice. Ask who holds the registration on your project, whether they stay involved through construction, and whether you can speak to them.
Yes, and the hybrid is common in Melbourne. You retain the architect under your own contract for design and planning, then engage a builder early on a fee basis to test buildability and pricing before documentation is finalised. Fees are higher, but you keep your independent advocate.
Design-and-build is usually quicker to a contract sum, because it removes the tender period. Planning approval timelines, though, depend on your council and your site rather than your procurement route. Where a heritage overlay applies, that stage dominates the programme either way.
Under design-and-build, the firm that drew the detail carries the cost of fixing it, because design and construction sit in one contract. Under the separate-architect route, responsibility must be established first: the architect may hold liability for a documentation error, the builder for workmanship.
Search the Architects Registration Board of Victoria register for architects, and the Building and Plumbing Commission register for builders. Confirm the registration class covers domestic building work at your scale, then check the registered name matches the entity signing your contract, not the trading name on the proposal.
Pick the structure that matches your site and your appetite for risk, not the one that sounds more reassuring. A constrained site and a design-led brief usually reward an independent architect. A settled brief, a tight programme and one accountable party point towards design-and-build, provided you arrange independent review yourself.
To talk through which fits your block, ROMAAC's team will walk you through both options honestly, including the cases where a separately appointed architect would serve you better.
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