Approvals of Knock-Down Rebuilds

A knock-down rebuild is the process of completely demolishing an existing dwelling and replacing it with a new dwelling (or dwellings). This is distinct from a partial demolition of a dwelling, which is categorised as an alteration and addition. There are several reasons why owners may desire to undertake a knock-down rebuild, including to resolve structural issues with an existing building, to subdivide a block of land, or when it is a more cost-effective option compared to undertaking a larger renovation involving structural layout changes. Comprehensive statistics on knock-down rebuilds are limited, and such projects are often masked within existing official housing statistics.

Knock-down rebuild projects are broadly split into two phases: the demolition and the new construction. The approvals for these two phases are both captured separately within the Building Approvals, Australia publication, but are not linked. This makes information on knock-down rebuilds not readily accessible within existing statistics. This article presents statistics on knock-down rebuilds through an experimental approach to linking existing data collected within the Building Approvals publication. For limitations on the data linking method used to produce the estimates and an explanation of the quality of the administrative data used, see the Methodology section below.

The Building Approvals, Australia publication has published data on the number of dwellings approved to be demolished across Australia extending back to the 2016/17 financial year, when 23,031 dwellings were approved to be demolished. Dwellings approved to be demolished has fallen since then to a level of 20,768 dwellings in the 2024/25 financial year.

The Australian Government has set a target to build 1.2 million well located dwellings between July 2024 and June 2029. The measure used to track this target is the gross number of new dwelling completions as captured in the Building Activity Survey. One method of development being employed to create more dwellings involves demolishing existing dwellings and rebuilding new dwellings on the same land. This article provides insight into these ‘knock-down rebuilds’ (KDR) by linking dwelling and demolition approvals that are already collected as a part of the Building Approvals, Australia publication.

For the purposes of this article, a knock-down rebuild (or knock-down rebuild project) is defined as an approval for demolition of an existing dwelling that is linked with an approval for construction of a new dwelling/s on the same property, within a three-year period. For example, if a house was demolished at a single address, the address was then subdivided into two address and new houses were approved to be built on this land within three years, this would be captured as one dwelling being demolished with two being rebuilt in its place (a two-for-one project). This is distinct from other types of development, such as greenfield development where buildings are developed on land on which buildings had not previously existed. For a full understanding of the methods applied and definitions, see the Methodology section. For this article, the 'date' of a knock-down rebuild is defined as the date on the building approval form that has been linked with a demolition approval.

Between July 2019 and June 2025:

• 19.2% (214,483) of the total dwellings approved across Australia were knock-down rebuild projects.  
• 58.3% of knock-down rebuild projects were one-for-one replacement (where the rebuild dwellings was the same number as dwellings demolished).
• On average, 2.1 dwellings were approved in to be built in place of every dwelling demolished
• Knock-down rebuilds largely occurred in SA2s that were close to city centres
• The average approval value for detached houses in knock-down rebuilds was $729,121, more than double the average for all other detached houses ($355,478)
• The average time  between demolition and building approval was 5.7 months, with this lag declining to a low in 2021/22 of 5.24 months.

Between July 2019 and June 2025, there were 1,120,139 new residential dwellings approved to be built across Australia, with 19.2% of these approved on the same site as a dwelling demolition approval that occurred within the three years prior. This equates to 35,914 dwellings per year approved in KDRs, replacing an annual average of 16,753 dwellings approved to be demolished for a rebuild. As such, the net gain from KDRs has been an average of 19,161 dwellings per year.

Over the six-year span, the ratio of dwellings approved to be built in a knock-down rebuild to dwellings demolished in a knock-down rebuild was 2.1. That is, on average for every demolished dwelling, there is 2.1 built on the same site. This is sometimes referred to as the 'rebuild rate'. Breaking this rate down further based on what is built on the site of a knock-down rebuild highlights the sort of knock-down projects being undertaken. Where detached housing replaced demolished dwellings, the rebuild rate was 1.3, representing both one-for-one knock-down rebuilds and land subdivision following a demolition. In contrast, apartments had a higher rebuild rate of 9.5, representing projects in which all types of dwellings (detached housing, townhouses, or apartments) were replaced with an apartment building. The rebuild rate for approved townhouses was 3.0 dwellings per KDR. Unsurprisingly, this is more than twice the number of dwellings approved to be rebuilt than when detached housing was approved.  

By state, NSW approved the most dwellings in knock-down rebuild projects, approving 77,279 dwellings in these projects between July 2019 and June 2025. The second most popular state was Victoria, approving 70,570 dwellings in knock-down rebuild projects. Knock-down rebuilds aren’t as common in other states with Queensland (34,030 dwellings), Western Australia (15,813), and South Australia (13,884 dwellings) recording significantly less of these projects. While the differences amongst the states could be attributed to the total volume of dwellings approved in each state, it may also reflect differences in the types of builds and access to greenfield areas. 

One-for-one knock-down rebuilds represent a project where one detached house is demolished and replaced with one detached house build in its place. Despite a total rebuild rate of 2.1, most knock-down rebuild projects were one-for one projects (58.4%). This highlights the fact that most knock-down rebuilds are not adding to overall housing stock, but instead are used as a means of significantly upgrading an exiting detached dwelling.  

Two-for-one KDR projects are typically situations where a detached dwelling is demolished, the land subdivided, and two dwellings built. This type of project, which adds one dwelling to net dwelling stock, represent 26.7% of all knock-down rebuild projects. 

While one-for-one knock-down rebuilds are by far the most common KDR project, there are differences notable between the states. On a state level, the Australian Capital Territory (74.9%), Queensland (74.4%), and Tasmania (71.2%) recorded the highest percentage of KDR jobs that were a one-for-one project. Accordingly, knock-down rebuilds in these states are less likely to add to existing dwelling stock. This rate was lower, but still overall quite high in other states: Western Australia (59.3%), Victoria (57.0%), the Northern Territory (53.5%), New South Wales (54.8%), and South Australia (49.9%). While these states are significantly lower than the ACT, Queensland or Tasmania, they remain around or over 50%, highlighting that knock-down rebuilds across all states are more often than not used to replace an existing dwelling, rather than to increase the density or supply of housing.

Most knock-down rebuilds occur in areas that are previously developed or established areas around each of a state's capital city. This is excluding the most populated, inner-city areas of capital cities that have already been developed. The maps below highlight the Statistical Area Level 2 (SA2) areas around Sydney and Melbourne that have the highest number of KDR projects. KDR in these areas are generally motivated by either a desire to replace an ageing property, or to increase the number of dwellings on a well-located piece of land.

KDR projects in Queensland however are different. While there are KDR projects in the developed areas around Brisbane, there is also a large number that stretch down the Queensland coast.  

The average approval value for a detached house built as part of a KDR project has consistently been higher than the average approval value for detached housing built not as part of a KDR project (such as houses built in greenfield areas). In fact, the gap in average approval values for houses as part of a KDR versus houses not as part of a KDR has continued to widen. In 2019/20, detached housing build through a KDR was 73% more expensive than detached housing build not through a KDR project. In the 2024/25 financial year, this gap increased to 132%. 

There are two primary reasons for this difference. Firstly, the value of detached houses not built through a KDR largely comes from cheaper forms of development such as greenfield expansion, which tend to have lower average approval values. In contrast, one-for-one knock-down rebuilds (especially those in inner suburbs of capital cities) are more likely to choose more expensive and luxury options for construction.

It should also be noted that the values in the below graph for KDRs is the building approval value only, and the cost of demolition is a separate cost on top of the numbers presented in the graph below.

In the 2024/25 financial year, the average time between the demolition approval and building approval was 5.60 months. The most recent numbers are low compared to the previous financial year (6.23 months in 2023/24) and the peak of 6.26 months in 2019/20. 

Breaking this down by the type of dwelling approved to be built highlights the challenge for building apartments though a knock-down rebuild. The average time between demolition and building approval for an apartment was only 6.7 months in 2019/20. This has significantly increased over time, reaching a high of 11.1 months in 2024/25. This means that new apartment buildings built as part of a KDR project take almost a year between the demolition approval and construction approval.

There are some minor variations in average time between demolition and building approval that can be seen in other dwelling types (detached and semi-detached housing).

The statistics in this article is sourced from linking demolition approvals and building approvals from the Building Approvals publication. Records are linked based on site address and/or Address Register ID (ARID). In order to link the records and provide useful statistics, the following definitions and restrictions were used:

• A knock-down rebuild is defined as an approval for demolition of an existing dwelling that is linked with an approval for construction of a new dwelling/s on the same property within a three-year period.
• Non-residential buildings are not considered in scope of this article. This means that both replacing a non-residential building with a dwelling (that is, a net addition to dwelling stock) and replacing a dwelling with a non-residential building are not included in this analysis. 

Data for demolition approvals was used from July 2016 to June 2025, while data for dwelling approvals were used from July 2019 to June 2025. This was done to ensure every dwelling approval had the opportunity to match to a demolition within the three-year period prior. Accordingly, this article excludes any potential knock-down rebuild projects in which the ABS has only received the demolition approval.

Building Approvals operate under the ABS-owned Functional Classification of Buildings (FCB) for classifying building jobs. 

For the purposes of this article, a one-for-one knock-down rebuild project represents a project in which one detached dwelling was demolished and replaced with one new dwelling. Subdividing land and building two new houses on the site of one demolished dwelling is defined as two-to-one.  

As mentioned earlier, the ABS has linked the demolition approval and building approval records using site address and/or ARID. From this process, 91.7% of all demolition approvals records from July 2019 and June 2025 were matched with a dwelling approval record (or records in the case of subdivisions) at the same site. In order to quality assure the estimates, the ABS selected a random sample of the unmatched demolition records and did an in-depth analysis of why the demolition approvals could not be matched to a building approval. Below are the results of this in-depth analysis, highlighting why the demolition approval was not matched to a building approval record:

• No subsequent building approval occurred on site after demolition approval: 40.9% of all unmatched demolition approvals
• No demolition ever occurred: 20.2% of all unmatched demolition approvals
• Insufficient address information was provided to link records: 11.6% of all unmatched demolition approvals
• Linked approval was out of scope of this article: 27.3%