PRICING · THREE HAT BUILDINGS
Consultants & Specialist Trades²
Rates last reviewed Match 2026
Most people budget for the build. Fewer budget for what makes the build possible. Consultants and specialist trades typically add 3–5% to the total cost of a custom home — and most of them are not optional.
TYPICAL CONSULTANT COSTS
3% - 5%
of estimated construction cost
EXAMPLE: $1.0m HOME (BUILD ONLY)
$30k – $50k
Consultant & specialist cost range
What mistakes do homeowners make early in a renovation or build?
Most homeowners do not under-budget consultants because they are careless. They under-budget because nobody explains which ones are required, when they get engaged, and what happens if they are left too late.
1
Not budgeting for consultants at all The construction quote covers the build. It does not cover the structural engineer, the building surveyor, the energy assessor, or the soil test — all of which are required before a permit is issued. These are separate engagements that need to be in the budget from the start.
3
Treating project-specific consultants as optional extras
A bushfire consultant is not optional if the site is in a BAL zone. A traffic engineer is not optional if the council requires one. Understanding which consultants your specific site and brief require — before design begins — is part of what keeps a budget honest.
2
Engaging consultants too late A soil test commissioned after concept design can reveal conditions that require the structure to be redesigned. A planning overlay discovered late can change what is approvable entirely. Early engagement is almost always cheaper than late discovery.
4
Assuming the architect handles everything A good architect coordinates consultant input into a coherent design. But most consultants are still separately engaged and invoiced. Understanding who appoints whom, and when, avoids gaps later.
The decisions that create the most downstream cost are usually the ones made or skipped, before the design has started. Consultants are where that shows up most clearly.
Required consultants
These are engaged on almost every project regardless of site or brief. Many are required before a building permit can be issued. Skipping or delaying any of them typically creates problems at permit stage, during construction, or both.
| Consultant | What it covers | Typical cost |
|---|---|---|
| Property InformationTitle, overlays, planning controls | Confirms what the site is subject to — overlays, easements, planning controls. Should be one of the first things ordered. Discoveries here shape everything that follows. | $500 – $1,000 |
| Land Feature SurveyExisting site conditions | An accurate survey of boundaries, levels, existing structures, trees, and services. The architect cannot design properly without it. | $2,500 – $4,500 |
| Title Re-establishmentBoundary confirmation | Confirms where the legal boundaries actually sit on the ground. Particularly important on older properties or sites with unclear fencing. | $1,000 – $2,500 |
| Arborist ReportTree assessment | Required on most sites with established trees. Identifies protected species, construction exclusion zones, and what can or cannot be removed. | $500 – $2,000 |
| Geotechnical ReportSoil test | Determines soil type and bearing capacity. Directly informs the structural engineer's footing design. Commissioned after concept design, it can require the structure to be redesigned. | $500 – $2,500 |
| Structural EngineeringDesign specific | Required for building permit. Covers footings, framing, beams, and non-standard structural elements. The more complex the design, the more engineering time is involved. | $5,000 – $20,000 |
| Energy AssessorNatHERS rating | Required by the building code. Assesses the thermal performance of the design. Engaging early allows adjustments to be made to the design rather than retrofitted around it. | $500 – $2,500 |
| Building SurveyorPermit & inspections | Issues the building permit and conducts mandatory inspections during construction. Fee depends on design complexity and the number of inspections required. | Design specific |
| Cost EstimatorIndependent estimate | Provides an independent construction cost estimate against the documented design. Useful before going to tender or when a builder's quote needs to be sense-checked. | $2,000 per report |
Costs last reviewed May 2026. Individual quotes will vary based on site, scope, and consultant. Always obtain your own quotes.
Most projects do not require every consultant listed below. The goal is not to engage more people than necessary — it is to understand which decisions require specialist input before those decisions become difficult to reverse.
Project-specific consultants
These are engaged depending on the site, the brief, or requirements identified during design. Some become mandatory once certain thresholds are triggered — a BAL rating, a planning overlay, a council condition. Others are genuinely discretionary.
Items listed as "incl. in construction cost" are quoted by the relevant trade as part of their scope. They are listed here because they are commonly mistaken for additional consultant costs on top of the build.
Costs last reviewed May 2026. Individual quotes will vary based on site, scope, and consultant. Always obtain your own quotes.
Most projects do not require every consultant listed below. The goal is not to engage more people than necessary — it is to understand which decisions require specialist input before those decisions become difficult to reverse.
What does a complete project budget actually look like?
A complete project budget has three components. Most early budgets only include one of them.
| Construction cost | The builder's contract price for the physical work |
| Architecture & design fees | Typically 8–15% of construction cost |
| Consultants & specialist trades | Typically 3–5% of construction cost |
| Add contingency | 10–15% across the total |