Site costs explained

When building an Arden home, we will always be up front and transparent about your site costs. Here we explain what site costs are, why they vary and provide insight to how they're calculated.

What are site costs?

To prepare a site for construction, there are two key areas of preparation that attribute to overall site costs:

1. Site infrastructure

These are mandatory items we require in order to commence work on your site. These include but are not limited to; building permit and fees, contour and soil test reports, builder's construction and warranty insurance and temporary security fencing. A full list of these costs are provided in our initial quote.

2. Site works

These costs are incurred as a result of actual works needed to prepare your site for construction. Costs can vary and will be determined after various tests are conducted on your site. For example, cost variations can occur due to:

  • A slab upgrade as a result of soil conditions, fall (or slope) and fill
  • A requirement for retaining walls
  • Additional fill
  • Excess soil removal
  • Rock removal
  • Instalment of services if needed (eg gas, water)
  • New estate covenants

Why do site costs vary?

Site costs can vary depending on the type of soil, extent of engineered fill and slope on your block. They type of soil and slope determine how your house must be built. For example, the key reason for soil testing is to establish how likely it is that the soil will move, expand and contract with different levels of moisture content.

We organise for an engineer to conduct a soil and contour test to establish the best type of foundation to suit the soil and fall of the block.

How are site costs calculated?

Your site costs will be calculated based on the specific attributes of your block. For example, the more problematic the soil and greater the slope, the more this will add costs due to increased levels of site preparation required.

As a guide, here is a list of soil classifications according to Australian Standard AS 2870/2011 – Residential slabs and footings.

Site classifications and movement based on soil reactivity

Class Foundation
A Stable, non-reactive. Most sand and rock sites with little or no ground movement likely from moisture changes.
S Slightly reactive clay sites with only slight ground movement from moisture changes.
M Moderately reactive clay or silt sites, which can experience moderate ground movements from moisture changes.
H Highly reactive clay sites, which can experience high ground movement from moisture changes.
E Extremely reactive site, which may experience extreme amounts of ground movement from moisture changes.
P Problem sites which include soft soils, such as soft clay or silt or loose sands; landslip; mine subsidence; collapsing soils; soils subject to erosion; reactive sites subject to abnormal moisture conditions or sites which cannot be classified otherwise. The ability of the soil to evenly bear a load is very poor and ground movement from moisture changes may be very severe.

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To learn more about some of the terms used in this article, head over to our Glossary of building terminology page.