What Do Site Costs Actually Include?
One of the biggest shocks for home buyers is discovering thousands of dollars in extra site costs after signing. Learn what site costs usually include, what provisional allowances mean, and what to ask before signing your contract.
Cost estimates only: Any building or upgrade figures in this guide are indicative, not fixed prices or quotes. Costs and inclusions vary by project, supplier, location and time. Confirm current written prices and specifications directly with your builder, suppliers and relevant trades.
What Are Site Costs?
Site costs are the preparation costs required to make your block of land ready for construction to begin. They are charged separately from the house price itself and cover a wide range of earthworks, engineering, and utility connection tasks.
Unlike the house price — which is relatively predictable — site costs are highly variable. Two identical houses on different blocks can have dramatically different site costs based on soil conditions, slope, proximity to services, and council requirements.
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What Do Site Costs Typically Include?
Typical Site Cost Ranges
While every site is different, here are indicative ranges commonly seen in South East Queensland:
| Scenario | Typical Range |
|---|---|
| Flat block, standard soil, close to services | $8,000 – $18,000 |
| Slightly sloped, standard soil | $15,000 – $30,000 |
| Steep or complex block | $25,000 – $55,000+ |
| Rocky ground or reactive soil (H/E class) | $20,000 – $60,000+ |
| Remote or difficult site access | $15,000 – $40,000+ |
Indicative ranges only. Always request a written site cost estimate before signing any contract.
Why "Fixed Price" Doesn't Always Mean Fixed
Many builders advertise "fixed price" builds, which can give buyers confidence that the price won't change. However, fixed price typically refers to the house itself — site costs are frequently handled separately through provisional allowances.
A provisional allowance (PA) is a budget estimate in your contract for a cost that can't be confirmed until the block is assessed or construction begins. Common provisional allowances include:
Rock Removal
Often provisioned at a capped amount — excess rock removal is charged per cubic metre above the allowance
Site Works / Earthworks
Estimate based on assumed soil class — can increase if soil conditions are worse than expected
Retaining Walls
On sloped blocks, retaining may be provisioned or excluded entirely — often one of the largest variable costs
Note
Soil Classifications Explained
Soil classification is one of the biggest drivers of site costs. Before building, a geotechnical engineer tests your soil and assigns a classification — which determines what type of slab and footing system your home requires.
Higher reactive soil classes require more reinforcement, deeper footings, and in some cases specially engineered slab designs — all of which add cost.
| Soil Class | Description |
|---|---|
| Class A | Sand or rock with negligible movement |
| Class S | Slightly reactive clay |
| Class M | Moderately reactive clay |
| Class H1 | Highly reactive clay (< 40mm movement) |
| Class H2 | Highly reactive clay (40–60mm movement) |
| Class E | Extremely reactive or abnormal soil |
Tip
Compare builders and how they handle site costs
Some builders offer fixed site cost packages — compare them side-by-side at no cost.
Questions To Ask Builders Before Signing
Use this checklist when reviewing your building contract or having pre-sign discussions with a builder. The goal is to ensure you have written clarity on what's included and what could change.
Hidden Costs Buyers Often Miss
Beyond the standard site cost items, there are several costs that frequently catch buyers off guard — either because they're listed as provisional allowances, excluded from the contract, or simply not discussed until construction begins.
Retaining walls
Often provisional or excluded on sloped blocks — can add $10k–$60k+
Stormwater management
Council requirements vary — some areas require retention tanks
Sewer connection
Distance from mains can add significant cost if connection point is far
Upgraded slab
H1/H2 or E class soils require engineered slabs at extra cost
BAL (Bushfire Attack Level) requirements
Applies in designated bush fire zones — affects materials and construction
Acoustic requirements
Properties near roads, train lines, or flight paths may need acoustic upgrades
Driveway and crossover
Not always included — council crossovers can be a separate cost
Rock removal
Often capped at a provisional allowance — excess rock is charged separately
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Frequently Asked Questions
All information is independently compiled as a general guide only. Site costs and soil conditions vary significantly between properties and states. Always obtain a written site cost estimate and soil test before signing any building contract.
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