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What is the cost to knock down and rebuild? In this blog, we’ll explain how to calculate a knockdown rebuild cost if you’re building a new home in Sydney and NSW.


With property prices in Sydney and NSW soaring like never before, many home owners are trawling the internet to find an accurate knockdown rebuild cost for their existing property.

Though information on building a new home is accessible in merely seconds, it’s not quite the same when it comes to calculating the cost of a knockdown rebuild.

The best way to explain the cost to knock down and rebuild is to imagine you’re buying a new car. What is the cost of a new car?

Well, that depends on many things.

Firstly, what’s your budget? What can you afford?

Is it a 2.0 litre engine or a 4.5 litre engine?

Will you have cloth or leather seats?

How many inch alloys do your tyres have?

Do you drive an auto or manual?

Is the car powered by petrol, diesel or electric?

Listed are only few of thousands of potential options – and that’s just for a car!

Building a new home involves significantly more variations than buying a new car. With so many factors such as land size, site conditions, council requirements and what you choose to put in your house at play, there’s no straight-forward answer on the cost.

It probably feels frustrating to not get immediate answers, however, there is a way to calculate the price if you extend yourself to more detailed research.


A guide to your knock down rebuild cost calculator

Just like cars, all houses are different.

Houses come in different shapes and sizes. Floor plans vary, generally starting from three bedroom all the way up to six bedrooms and more.

What is important to note is the house design will depend entirely on land size, width and depth. Therefore, there’s no way to pick out your design without first getting an understanding of your block.

Furthermore, new homes are largely regulated by local council. In addition, environmental factors such as soil, rock, slope, flooding and bushfire risk can also determine how much work is needed to prepare your site for building.

Just like cars, you can pick and choose what’s included in your new home. Each thing you add onto your home that isn’t a standard inclusion will bump up the overall price of your knockdown rebuild, making it impossible to land on a single figure in a matter of seconds.

So, let’s circle back to the main question. What is the cost to knock down and rebuild? The short answer can be calculated as follows:

Knockdown rebuild cost = drafting and design + demolition + site costs + building + inclusions

Knockdown Rebuild | Worthington Homes


Knockdown Rebuild | Worthington Homes



How we present your cost to knock down and rebuild

In order for you to budget, plan and obtain finance from a lender, you need to know the entire knockdown rebuild cost upfront.

Therefore, before we submit the final tender and before you sign a contract, the estimated cost of the build project from start to finish is firstly presented to you.


1. Drafting and design

Drawing up house plans is included if you pick a design from our range. We offer standard house plans or we can draft a custom home design.

Most builders will advertise a house design at a base price – excluding demolition, site costs and inclusions. If you see a bargain price on a home (such as anything under $200K), then it’s probably too good to be true.

We operate quite differently.

Our costs cover everything – so there are no surprises along the way. If there’s something not included, such as a variation to your house specification then we’ll let you know upfront.

Make sure you advise us of your specific needs, so we can include it in the quote.


1. Demolition costs

The cost to demolish your house can vary, depending on what needs to be demolished and other things such as hazardous material, trees, fencing and neighbouring structures.

Do you own a home containing asbestos? Then you’ll require safe removal and disposal. If your home was originally built prior to or before 1980, it’s very likely to contain asbestos.

Are there established trees in your property? An arborist will need to remove the trees and you may also require a permit from council for removal.

As a guide, demolition costs can start at $15,000 and go up to $50,000 on very complex jobs.

Until we look at your land, we won’t be able to quote accurately, which is why it pays to talk to us directly for an estimate on demolition.


2. Site costs

Like demolition costs, site costs vary greatly depending on the condition of your site.

Do you live in a bushland area with old trees? There may be costs for stump and root removal.

Are you on a block containing bedrock? The ground may require additional excavation services to break up and cut the rock.

Is your block sloping? Site access may be tricky and you may require traffic control services.

Are you neighbouring a national park or reserve? If yes, some house materials will need to be bushfire proof. Reports will be required to assess the bushfire risk of your house.

Is your suburb prone to flooding? We may need to tweak the design of the house to meet flood zoning requirements.

Since there are so many variables for each build, there’s no such thing as a ‘one size fits all’ price. The best way to get an accurate cost is to forward any site, soil and contour plans for assessment by a qualified builder. All things above plus much more are all part of the service we provide.


4. Building costs

This is where you get the most variation in price. Considering over 4000 elements come together when building a new home, you’re looking at over 100,000 possible variations.

The cost to knock down and rebuild is going to depend on what you choose to put into your home.

Everything from your ceiling height to the thickness of the kitchen stone benchtop, your choice of carpet, tiles or laminate flooring – as well as thousands of other options.

While we have two levels of inclusions that are included in the tender price, you can also choose to upgrade. For example, you may want larger kitchen appliances or you might like to install an outdoor kitchen in the alfresco area.

More luxurious light fittings, security features, premium tapware and an upgraded façade can all drive up the knockdown rebuild cost – but only as you define it.


In summary, a knock down rebuild ‘cost calculator’ doesn’t really exist because human input is required to assess and estimate all the different variables.

If you’d like an obligation-free estimate to get a ballpark knockdown rebuild cost, simply submit your site plans and requirements in a house design.

We offer a free first initial consultation at our Showroom in Castle Hill or at our Display Home in Schofields if you’d like to come in for a chat.

We hope you found this article helpful and if there’s any questions you’d like to ask, feel free to contact us by calling 1300 30 11 38 or completing the enquiry form.


You read all about our knockdown rebuild project in Baulkham Hills here.

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