Site Costs Explained for Australian Home Buyers

17th July 2023

Finance & Budgeting Pre-Construction Legal & Contracts First Home Buyer Investor Upsizing & Downsizing

Learn what site costs cover when building a home in Australia, what can increase them and how to compare fixed site costs, allowances and exclusions.

Site costs explained - what to check before building a home in Australia

Two builders can quote very different site costs for the same block. One might include retaining walls and deeper footings, while the other might leave those items out or list them as estimates. Until you see what each figure covers, it’s hard to tell which quote will cost you more.

In the Home Building Hub episode Site Costs Explained, hosts Colin Bischof and Darren Brennan explain how builders estimate site costs, what can change after testing and what to ask before buying land or comparing quotes.

What are site costs when building a house?

Site costs cover work needed to prepare your block and adapt the foundations and drainage to its conditions. Your builder may include some of this work in the base house price and list the rest separately.

A site costs quote may include:

• Earthworks

  • excavating or levelling part of the block and removing excess soil.

• Foundation upgrades

  • changes to the slab, extra reinforcing steel or piers where the engineer specifies them.

• Retaining walls

  • holding soil in place where ground levels change.

• Drainage

  • managing stormwater and, where needed, water moving through the soil.

Ask for an itemised quote that shows which of these works the builder has priced and where each item appears.

What can increase site costs on your block?

Slope and fill

Builders use fall to describe the difference in height between two points on a block. A block can look flat from the street and still need excavation or retaining. Ask the builder to show you the proposed house and garage levels against the street and backyard. That makes it easier to see how steep the driveway will be and how you’ll get from the house to the yard.

Fill is material added to raise or level the ground. A lot that looks level may contain deep fill. Depending on its depth, condition and compaction, the engineer may specify piers to support the foundations.

Soil, rock and nearby structures

A soil test helps the engineer assess the ground and design suitable foundations. The builder’s standard slab may need extra reinforcement or piers for your block. The engineer may also consider nearby trees, easements and neighbouring footings when designing the foundations.

Ask how the builder has treated rock excavation in the quote. A soil test samples parts of the block, so some conditions may only become apparent once excavation starts.

Stormwater and drainage

The level of the stormwater outlet can affect how the site drains. If water can’t flow by gravity to the connection point, the drainage design may call for a pit and pump. Depending on the block, the engineer may also specify subsurface drains to intercept water moving towards the house.

Fixed site costs vs site cost allowances

Colin and Darren give rock removal and a change from bored piers to screw piles as examples of items worth asking about. Check the written scope even when the quote uses the word “fixed”.

What to check before buying land or choosing a builder

1. Ask the builder to review the block with your preferred floor plan.

   The plan of subdivision shows lot dimensions and may show easements. In a new estate, the civil engineering plans can help the builder make an early assessment of levels and fill.

2. Find out what the builder has confirmed.

   Ask whether the price is based on estate plans or on a soil test and level survey for your lot. Ask when the engineer’s slab design will be available and which figures it could change.

3. Check how you’ll use the finished site.

   Ask where retaining walls are proposed and how you’ll access the garage, front door and backyard once the final ground levels are set.

4. Compare the total build price for the same scope.

   One builder may include a slab specification in its base price that another lists as an upgrade. Line up the base prices, inclusions, allowances and exclusions before comparing the totals.

Glossary of site cost terms

• Site cut

  • excavation to create the required building level.

• Level survey

  • a survey that records ground heights across the block.

• Site classification

  • an assessment of ground conditions used to inform the foundation design.

• Piers

  • foundation supports that transfer loads deeper into the ground.

• Easement

  • an area of land set aside for a specific use, such as drainage or utility access.

Frequently asked questions

How much are site costs when building a house?

The cost depends on the block, the house design and what the builder already includes in the base price. Ask for an itemised estimate for your lot and confirm when site testing and engineering can refine it.

Can a flat block have high site costs?

Yes. Deep fill, rock, reactive soil or a difficult stormwater connection can add work even when the block appears level.

When will my builder know the final site costs?

A soil test, level survey and engineer’s foundation design give the builder more information to price the work. Some items may still be listed as provisional or excluded, so check what remains open when you review the contract.

Key Takeaways

• Check slope, fill, soil and drainage early, ideally before committing to a block.
• Ask what the builder has included in the base price and which site works appear as separate charges.
• Get fixed items, allowances and exclusions in writing, with a clear timeline for confirming estimates.
• Compare the total build price across builders using the same scope of work.

Watch or listen to Site Costs Explained with Colin Bischof and Darren Brennan on YouTube

About the Home Building Hub Podcast

The Home Building Hub podcast, hosted by industry experts Colin Bischof and Darren Brennan, is Australia’s premier resource for new home buyers. With weekly episodes featuring special guests, the podcast provides objective, high-quality insights into the home building process - completely free and without sales pitches. From understanding financing options to navigating the complexities of building a new home, each episode is packed with actionable advice and tips. Explore more episodes at http://www.homebuildinghub.com.au and join our growing community of informed home buyers.

Disclaimer

This article was generated by AI based on a transcript of our podcast episode and may contain inaccuracies or omissions. Whilst we’re all about providing value to you, this article should not be considered as legal or financial advice. It contains general information only and is based on the content discussed during the podcast episode. This information is relevant to the episode’s release date and may not be applicable at the time of reading. Always seek independent professional advice tailored to your personal situation before making any legal or financial decisions.

Quote itemWhat it means for your buildFixed site costsThe builder has priced a defined scope. Ask which works and site conditions the fixed figure covers and which are excluded.Site cost allowanceThe builder has estimated a cost using the information available. Ask which assumptions it relies on and when the amount can be refined.Provisional sumThe contract includes an estimate for a particular item of work. Ask how the builder will calculate any adjustment once the scope or actual cost is known.ExclusionThe quoted amount leaves out an item or condition. Ask who will organise and pay for the work if it’s needed.