Executive summary

Land amalgamation is an important tool in property development, enabling the ‘unpicking’ of existing property boundaries to create a larger combined site. This can potentially enable a far greater number of homes through using land more efficiently. Amalgamation, as defined in this study, is where two or more existing parcels or properties are combined and then redeveloped to a higher intensity.

Setback rules, fragmented ownership patterns and the small size of existing suburban properties act as barriers to higher-density redevelopment. Amalgamation can overcome these barriers and help achieve the quality compact approach to growth of the Auckland Unitary Plan (AUP) and the Future Development Strategy.  

This study of the Henderson-Massey Local Board area builds on the earlier research by Fredrickson et al. (2016), which analysed amalgamations in the Auckland region between 2004 and 2014. This was prior to when the AUP became operative. This study investigates amalgamation under the AUP.

To determine the quantity, location and characteristics of amalgamations, a spatial model was developed based on the methodology of Fredrickson et al. (2016). It identified where two or more existing properties were subdivided across their boundaries resulting in an increase in the number of parcels. The Henderson-Massey Local Board area was selected as the study area because it has the highest number of consented dwelling units, particularly intensive infill developments.

The study identified 96 amalgamations within the study area.

Using building consents to measure development, 1704 units were consented on the sites, an average of 18 units per site.

As a proportion of total residential development, amalgamated sites accounted for 14 per cent of units consented. Of these dwellings, 80 per cent were terrace units, 13 per cent were apartment units and the rest were detached houses. A high proportion of amalgamations occurred within the top two most intensive residential zones¹ .

Amalgamations which occurred on Kāinga Ora owned land accounted for 21 per cent of sites and 15 per cent of consented units.

Compared to the results of Fredrickson et al. (2016) in the Henderson-Massey Local Board area, the use of amalgamation moderately increased from 5.1 per cent of total development under legacy planning provisions to 14 per cent under the Auckland Unitary Plan.

A key research question posed by this study was whether amalgamations enable greater dwelling yield compared to a typical single parcel subdivision. Analysis found that development on amalgamated sites was only slightly denser compared to single parcel subdivision. This can be attributed to developers choosing to develop townhouses with parking areas rather than maximising dwelling yield with apartments. Therefore, all the potential theoretical gains in housing capacity were not taken up by developers who undertook amalgamation. This study does not examine the reasons why developers chose to develop at lower yields.

Overall, the study found that while making up a significant proportion of development, most development still occurred through single parcel subdivision. 

The findings of this study may provide useful insights for Plan Change 120 (notified in November 2025) and future plan changes. However, this study does not directly address the potential for amalgamation to drive increased apartment development in newly upzoned areas closer to the city centre.

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1. Terrace Housing and Apartment Building Zone and Mixed Housing Urban Zone.
 

Auckland Council, March 2026

See also

Residential property amalgamation and aggregation in Auckland, 2004-2014