Short answer
Site costs cover the work needed to prepare your land and connect the home to its surroundings: surveying, soil testing, demolition, excavation, footings, retaining walls, stormwater, service connections and making good afterwards. They are shaped by what sits below the surface and how the block sits in its street, which is why two blocks in the same suburb can differ substantially. A site assessment before the budget is fixed is the only reliable way to size them.
What site costs actually cover
Site costs are the work needed to prepare the land and connect the home to its surroundings. They can include surveying, soil testing, demolition, excavation, footings, retaining walls, stormwater, service connections, temporary site facilities, protection of neighbouring property and the repair of areas affected by construction.
Some of these items can be priced accurately once the design and site information are complete. Others remain allowances until the ground is opened or existing conditions are exposed. The aim is not to pretend that every unknown can be removed. It is to investigate the block properly, identify the likely risks and make the allowances clear.
Ground conditions below the surface
A contour survey and soil classification give the designer, engineer and builder essential information about the land. They help establish levels, boundaries and the footing system that may be required. Even with this information, excavation can reveal rock, uncontrolled fill, buried material or localised ground conditions that were not visible beforehand.
Rock excavation and changes to the footing design can have a meaningful effect on cost. If the full extent cannot be known when the contract is prepared, the relevant allowance should be realistic and easy to identify, rather than hidden inside a broad site works figure.
Slope, retaining and drainage
Canberra blocks range from relatively level sites to steep established properties. A sloping block can require deeper excavation, stepped floor levels, additional structural design, retaining walls and more complex movement of machinery and materials. The position of the home on the site can reduce or increase these demands.
Stormwater also needs to be resolved early. The design may need to manage falls across the land, lawful discharge, driveway levels, surface water and the relationship with neighbouring properties. Retaining walls, drainage and landscaping should be considered together because a decision in one area often affects the others.
Demolition, asbestos and existing services
For a knockdown rebuild, the budget needs to include more than the demolition contractor. Appropriate asbestos assessment, utility disconnections, permits, fencing, waste removal and the treatment of old footings, tanks or other structures may also be required. Mature trees and neighbouring structures can affect how the work is approached.
Existing water, sewer, electricity, gas and communications infrastructure also needs to be located and assessed. A new design may require services to be upgraded, relocated, protected or connected along a different route. On a townhouse project, separate connections and shared service arrangements can become a significant part of the civil design and cost.
Access and the surrounding site
Narrow frontages, established trees, overhead lines, busy roads and limited areas for storing materials can all affect construction. Restricted access may require smaller machinery, additional handling, cranes or carefully staged deliveries. These costs are easy to overlook when attention is focused only on the house.
The practical way to build a more reliable allowance is to walk the site early, obtain the right investigations and price the work against a developed design. Ask for site inclusions, exclusions and allowances to be shown clearly. Our guide to what affects building costs in the ACT explains how site conditions fit into the broader project budget. For new home projects in Canberra, the custom home builder in Canberra page explains how Ottimo Homes handles site assessment as part of the early project conversation.
Planning a project in Canberra? Start a conversation with Ottimo Homes.
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