How to Buy Land to Build On: 10 Things to Check Before You Offer

Buying land to build on demands a different kind of scrutiny to buying an established home — problems are buried in soil reports, council databases, and title documents rather than visible at an open inspection, and discovering them after exchange can reshape your budget entirely.

Land due diligence is non-negotiable

Unlike a house purchase where a building inspector can walk through the property, a vacant block reveals almost nothing on the day you inspect it. The real risks — contaminated fill, reactive clay, heritage overlays, flood affectations — sit in files, registers, and underground. A thorough pre-offer investigation typically costs a few thousand dollars; missing a single issue can cost tens of thousands in remediation, redesign, or aborted approvals.

1. Confirm the zoning and permissible uses

Zoning controls what you can build and how many dwellings. Residential low-density zones in most NSW, VIC, and QLD councils permit a dwelling and, in many cases, a secondary dwelling (granny flat). Some zones allow dual occupancy, multi-dwelling housing, or subdivision — each requiring different approval pathways and triggering different cost profiles. Check the council's planning portal directly and verify your intended use is permissible. Do not rely on the selling agent's summary; agents are not planners.

2. Review easements and covenants on title

An easement grants another party a right over part of your land — typically for stormwater drainage, sewer lines, overhead powerlines, or access. Building over or too close to an easement is generally prohibited, which can shrink the effective buildable area considerably. A covenant is a private restriction registered on title that can mandate minimum floor areas, require specific external materials, or prohibit certain uses entirely. Both instruments appear on the Certificate of Title. Engage a solicitor or conveyancer to review the title before making any offer.

3. Investigate flood and bushfire overlays

Check the council's flood maps and the relevant state authority's bushfire prone land mapping — the NSW Rural Fire Service, VIC's DELWP mapping, or QLD's state planning portal, depending on where the block sits. Flood-affected land may require finished floor levels to be raised above a defined flood planning level, adding cost to the slab and subfloor structure. Bushfire-prone land attracts a Bushfire Attack Level (BAL) rating under the NCC; BAL-29 or above can add indicative costs of $15,000–$50,000 or more to a standard build through upgraded glazing, ember guards, non-combustible cladding, and structural changes.

4. Assess the slope with a contour survey

Site preparation costs vary dramatically with fall. A near-level block typically requires indicative earthworks of $8,000–$15,000. A moderately sloped block requiring cut-and-fill and a concrete retaining wall can push that figure to $40,000–$80,000; a steep or complex block can exceed $100,000 when engineered retaining, pier-and-beam foundations, and access works are included. Timber retaining walls run at an indicative $380 per lineal metre; concrete or block walls cost more. Commission a contour survey — not just a verbal description from the agent — before you form a view on value.

5. Commission a soil test

Soil classification under AS 2870 determines your slab design and cost. Class A (stable, sandy soils) supports a standard slab at the lower end of the cost range. Class M or H (moderately to highly reactive clay) requires a stiffened raft or waffle-pod slab with deeper beams. Class P (problematic — soft, filled, or subject to collapse) can require piered or suspended slabs and specialist geotechnical engineering. A soil test costs an indicative $500–$1,000. Discovering you have Class H or P soil after signing a fixed-price building contract is a costly renegotiation.

6. Verify service connections

Confirm the block is connected — or readily and affordably connectable — to mains water, sewer, electricity, and telecommunications. Infill blocks in established suburbs almost always have services at the boundary. New release estates typically include developer-funded connections as part of the lot price, but verify this in writing. Rural and semi-rural blocks may have no access to mains sewer, requiring an on-site wastewater system (septic or ATU), which adds indicative costs of $10,000–$25,000 and imposes ongoing maintenance obligations. Check NBN or fibre availability separately if working from home is a consideration.

7. Obtain and read the Section 10.7 Planning Certificate (NSW)

In NSW, a Section 10.7 Planning Certificate — issued by the council — is a formal disclosure of all planning instruments and policies affecting the land, including flood, bushfire, heritage, biodiversity, acid sulfate soil, and contamination overlays. Equivalent certificates exist in VIC (Planning Certificate) and QLD (Property Search). Obtain one before exchange, or at minimum include a condition in your offer allowing you to review it. The full version (10.7(2) and (5)) costs slightly more but reveals informal constraints that the standard certificate does not.

8. Research council DA requirements and design controls

Beyond permissible uses, councils apply site-specific development controls: building envelope planes, setback requirements, maximum wall heights, BASIX energy and water targets, landscaping area ratios, and neighbourhood character guidelines. Some heritage conservation areas impose street-facing design controls that significantly constrain contemporary designs. Contact the council's duty planner or use their online DA portal to map these before engaging an architect or designer. A pre-DA meeting, available at most NSW and VIC councils, is a cost-effective way to get early guidance on a complex site.

9. Check for site contamination

Prior industrial, agricultural, or commercial land use — on the block itself or on adjoining land — can result in soil or groundwater contamination. Check council records, the NSW EPA's Contaminated Land Management register (or the relevant state equivalent), and ask the vendor directly via a Section 32 or equivalent disclosure statement. Remediation of contaminated land is expensive and can render a block unviable for residential construction without specialist works.

10. Scrutinise developer contracts for new release land

If you are buying in a new land release, review the plan of subdivision carefully for lot boundaries, easements, shared facilities, and any body corporate or owners corporation obligations. Pay particular attention to the sunset clause — the date by which the developer must register the plan of subdivision. Delays beyond sunset can give either party rights to rescind, which has caused significant disputes in tight markets. Check the developer's track record on delivering previous stages and confirm all infrastructure (roads, drainage, parks) that was represented at sale.

Quick-reference: key due diligence checks and who to engage

Check	Who to engage	Typical cost (indicative)
Title and easement review	Solicitor or conveyancer	$800–$2,000
Section 10.7 / Planning Certificate	Council (online)	$50–$150
Contour and feature survey	Licensed surveyor	$1,000–$2,500
Soil test	Geotechnical engineer	$500–$1,000
Flood and bushfire overlay check	Council portal / RFS / state authority	Free–$50
Contamination search	EPA register + council records	Free–$200

Once you have completed these checks and shortlisted a viable block, use DesignBuildSource's cost calculator to model indicative build costs for your site conditions, or search the professional directory to find a local surveyor, geotechnical engineer, or town planner who can assist with the more complex items before you commit.