Planning policy monitoring

Assessment of housing land supply

Introduction

The National Planning Policy Framework (NPPF) says that local planning authorities should illustrate the expected rate of housing delivery through a housing trajectory for the plan period and set out how they will maintain delivery of a five-year supply of housing land to meet their housing target.

All local authorities are required to identify and update annually a supply of specific deliverable sites sufficient to provide a minimum five years’ worth of housing against their housing requirements set out in adopted strategic policies or against their local housing need where the strategic policies are more than five years old. The NPPF states that where planning authorities cannot demonstrate a five-year supply, the relevant policies for the supply of housing should not be considered up-to-date and the ‘presumption in favour of sustainable development’ should apply. This means granting consent unless the application of policies in the framework that protect areas or assets of particular importance provides a clear reason for refusing the development proposed or the adverse impacts of doing so would ‘significantly and demonstrably’ outweigh the benefits when assessed against the policies in the framework taken as a whole. The ability to identify a five year supply of deliverable housing is therefore significant in dealing with planning applications for housing.

Local planning authorities should also identify a supply of specific developable sites or broad locations for growth for years 6 to 10 and where possible, for years 11 to 15 of the plan.

This sets out the deliverable and developable housing land supply for North Northamptonshire up to 2031 and identifies the current five-year land supply position. The full picture for the North Northamptonshire area is provided within the Authority’s Monitoring Report (AMR).

Housing requirement

The North Northamptonshire Joint Core Strategy (JCS) was adopted in July 2016. It sets out the housing requirements for the area. Policy 28 of the JCS sets out the following housing requirements across North Northamptonshire:

Table 1: Share of objectively assessed needs in the housing market area

The distribution of housing in the JCS is urban focused, with the four growth towns being defined as the most sustainable locations for development. The Sustainable Urban Extensions in the urban areas are the key building blocks for North Northamptonshire for the plan period and beyond. The plan also supports development to meet local needs and aspirations in the rural area.

The housing requirements set out in Policy 28 of the Joint Core Strategy (JCS) applied until July 2021, when the plan became 5 years old. National policy (NPPF, paragraph 78) states that where strategic policies are more than five years old the supply should be assessed against Local Housing Need (LHN) calculated using the Government’s standard method.

Table 2: Local housing need for North Northamptonshire from the new standard method

The approach to reporting housing land supply on a North Northamptonshire-wide basis rather than staying with the former local planning authority areas (as some other new unitary councils in the UK do) was agreed at the North Northamptonshire Planning Policy Executive Advisory Panel in June 2021.

Identifying the supply of deliverable and developable sites

Existing planning consents do not represent the only source of housing land supply when identifying deliverable or developable sites. As referred to above, the local authority is required to identify five years’ worth of deliverable sites and 6 -15 years’ worth of developable sites.

The NPPF defines what is meant by deliverable in the glossary at Annex 2:

To be considered deliverable, sites for housing should be available now, offer a suitable location for development now, and be achievable with a realistic prospect that housing will be delivered on the site within five years. In particular:

a) sites which do not involve major development and have planning permission, and all sites with detailed planning permission, should be considered deliverable until permission expires, unless there is clear evidence that homes will not be delivered within five years (for example because they are no longer viable, there is no longer a demand for the type of units or sites have long term phasing plans).

b) where a site has outline planning permission for major development, has been allocated in a development plan, has a grant of permission in principle, or is identified on a brownfield register, it should only be considered deliverable where there is clear evidence that housing completions will begin on site within five years.

The latest National Planning Practice Guidance (NPPG) (Paragraph: 007 Reference ID: 68-007-20190722) further advises that:

In order to demonstrate 5 years’ worth of deliverable housing sites, robust, up to date evidence needs to be available to support the preparation of strategic policies and planning decisions. Annex 2 of the National Planning Policy Framework defines a deliverable site. As well as sites which are considered to be deliverable in principle, this definition also sets out the sites which would require further evidence to be considered deliverable, namely those which:

• have outline planning permission for major development
• are allocated in a development plan
• have a grant of permission in principle
• are identified on a brownfield register

Such evidence, to demonstrate deliverability, may include:

• current planning status – for example, on larger scale sites with outline or hybrid permission how much progress has been made towards approving reserved matters, or whether these link to a planning performance agreement that sets out the timescale for approval of reserved matters applications and discharge of conditions
• firm progress being made towards the submission of an application - for example, a written agreement between the local planning authority and the site developer(s) which confirms the developers’ delivery intentions and anticipated start and build-out rates
• firm progress with site assessment work
• clear relevant information about site viability, ownership constraints or infrastructure provision, such as successful participation in bids for large-scale infrastructure funding or other similar projects

The NPPF also defines what is meant by developable:

‘To be considered developable, sites should be in a suitable location for housing development with a reasonable prospect that they will be available and could be viably developed at the point envisaged.’

The following sources of housing land supply have been examined to identify sites which are deliverable or developable:

• Existing commitments (sites currently under construction and sites with valid planning consent)
• Sites with a resolution to grant consent subject to S106 agreements
• Site where pre-application discussions are well advanced
• Sites in adopted Development Plans
• Additional capacity within the Sustainable Urban Extensions (SUEs)
• The North Northamptonshire Brownfield Land Register
• Housing for older people, including residential institutions in Use Class C2
• Communal accommodation
• Housing delivered through permitted development rights or prior notification such as flats above shops or office conversions
• Windfall sites (see below)

Windfall allowance

The NPPF defines windfall sites as those which have not specifically been identified in the development plan. They normally comprise previously developed sites that become unexpectedly available. Local planning authorities can make a windfall allowance in the five year supply if they have compelling evidence that such sites have consistently become available and will continue to provide a reliable source of supply.

Evidence of past windfall delivery is provided in Appendix 1. The data has been collected slightly differently across the previous authority areas. It does however clearly demonstrate that these have made a significant contribution to the supply of housing in the area. The total amount of windfall completions has been gradually falling over recent years as completions on sites allocated within the local plan continue to rise. The contribution of small sites is however fairly consistent. It is therefore reasonable to assume this source of supply will continue at a similar rate. An allowance of the average of these years on sites below 10 dwellings can be applied to the anticipated housing supply. A separate windfall allowance is applied for each of the previous areas as this takes account of the slight differences in the nature of these areas, for example the Corby area has traditionally had less windfall as it is a largely reliant on large new allocations and has fewer settlements. In addition, separating the windfall total provides greater clarity for infrastructure providers of the location of anticipated supply e.g. for transport modelling. In order to avoid double counting of smaller sites with an extant planning permission, this element of supply is only included from year 3 onwards in the 5-year assessment period.

Lapse rate

It is reasonable to assume that not all planning permissions granted will be implemented, particularly on the small sites. In order to ensure a robust approach, there is a need to make an allowance for non-implementation (or lapse rate) of a proportion of the permissions. An assessment of the actual lapses in the area has been undertaken. The results are shown in Appendix 2.

Based on the local evidence it is reasonable to apply a 9% lapse rate to sites with permission for less than 10 dwellings within the Kettering and Wellingborough areas, an 8% lapse rate in Corby and a 4% rate within the East Northants area. Not all of the sites with more than 10 dwellings will all be completed within the plan period; this particularly applies to the SUEs and other strategic sites. Delivery rates on these sites are however dealt with in the trajectory, rather than through application of a lapse rate.

Communal accommodation

It is reasonable to include communal accommodation as part of the supply where this could be considered as part of the dwelling stock. This includes student accommodation, houses in multiple occupation and housing for older people including residential institutions in Use Class C2. Total net change for communal accommodation is as reported in the Housing Flows Return and as used for the Housing Delivery Test. Calculated as number of bedrooms adjusted by the communal net change national ratio of 1.9. The ratios for both net student and net other communal accommodation are found in the Housing Delivery Test measurement rule book.

Housing trajectory

Those sites from the sources listed above which have been considered as deliverable or developable are in Appendix 3. For each site an assessment has been made as to when the site can commence and the likely build out rates, this takes account of information from the site’s developers where this is available. On the smaller sites (sites of less than 10 dwellings) it has been assumed that they will be delivered before the consent expires (unless there is evidence to the contrary) then a lapse rate has been applied to the total. Dwellings under construction as at 31 March 2025 are assumed to be completed by 31 March 2026 unless there is specific local knowledge that this is not likely to be the case. For other sites, evidence from site promoters has been taken into account where available alongside information on past delivery rates. Delivery questionnaires were sent to site promoters of all major sites and site allocations.

A significant amount of literature is published exploring the delivery of major residential development. Inevitably, each example is unique and specific to the local circumstances. For this reason delivery information from the site promoters, as they know the specific details of the site, is taken into account together with evidence of past delivery. Certain trends can however be identified. Whilst there will be many influences on a forecast housing trajectory from a strategic site, it will essentially be dictated by the rate of sales that the site’s developers want and are able to achieve in light of site conditions, business strategies and wider market demand. A large site would typically involve multiple developers who would be active at any one time. The precise number of active sales outlets at any one time could vary, but would typically start with a few (especially when creating a new ‘place’) and increase over time to a steady state. How many active outlets exist on one site will vary depending on the specific circumstances. For well-established sites in strong areas this could get as high as 10 to 15 outlets. Some of the larger national builders can even operate more than one outlet off a single site, and run these as entirely separate construction and sales outlets under different brands or aimed at different market segments. As the number of separate sales outlets grow, the overall build rate will increase. Evidence suggests that completions from a single outlet can range from around 30 to 50 units per annum.

The purpose of the housing land supply report is not to predict what will be built, but to identify land supply that is deliverable. The council can influence land supply, but it can have limited impact on the wider economic and financial climate that may affect house building and sales.

Five year supply of deliverable sites

Appropriate buffer

When identifying a five year supply, the NPPF requires the addition of a 5% buffer to the housing requirement to add choice and competition in the market. This rises to a 20% buffer where there has been significant under delivery over the previous three years. There is also an option for a 10% buffer on production of an annual position statement agreed by the Secretary of State.

The NPPF (paragraph 78) says that significant under delivery will be measured against the Housing Delivery Test and will be defined as delivery below 85% of the housing requirement.

The 2023 Housing Delivery Test published in December 2024 remains the most up-to-date published version and covers the period 2020/21, 2021/22 and 2022/23.

Housing Delivery Test (%) = Total net homes delivered over three year period / Total number of homes required over three year period

Details of how the homes required is calculated is provided in a technical note. It is based on projections of household growth and affordability. In order to reflect the national disruption caused to housing delivery by the pandemic to starts and completions, construction, and monitoring of completions, the period for measuring the homes required in 2020 and 2021 year has been reduced by 4 months.

The homes delivered figure is based on the net additional dwellings calculated by local authorities with an adjustment for communal accommodation. The following table sets out the results for North Northamptonshire.

Table 3: Housing delivery test - 2023 Measurement

It can be seen that delivery does not constitute significant under delivery as defined in the NPPF. It is therefore appropriate to continue to use a 5% buffer.

Treatment of past under-provision

When measuring five year supply against development plan targets the Planning Practice Guidance states that ‘The level of deficit or shortfall will need to be calculated from the base date of the adopted plan and should be added to the plan requirements for the next 5 year period (the Sedgefield approach) then the appropriate buffer should be applied. If a strategic policy-making authority wishes to deal with past under delivery over a longer period, then a case may be made as part of the plan-making and examination process rather than on a case by case basis on appeal’ (Paragraph: 031 Reference ID: 68-031-20190722).

Where the standard method for assessing local housing need is used as the starting point in forming the planned requirement for housing, the Planning Practice Guidance states that ‘Step 2 of the standard method factors in past under-delivery as part of the affordability ratio, so there is no requirement to specifically address under-delivery separately when establishing the minimum annual local housing need figure’ (Paragraph: 031 Reference ID: 68-031-20190722).

As the JCS is over five years old, the JCS requirements are now superseded by local housing need using the standard methodology. On the basis of the above guidance there is no longer a need to take account of any shortfall against the JCS when calculating the 5 year housing land supply.

Five year supply requirement

The five year supply requirement is calculated below based on local housing need and the application of the 5% buffer.

Table 4: Five year supply requirement

Deliverable sites

Appendix 3 sets out the summary of the source of supply of deliverable and developable sites. It also takes account of the lapse rate and includes the windfall allowance. The schedule of sites provides a total supply of 11,017 dwellings within the five year period. The source of supply is summarised below.

Table 5: Source of housing supply 2025/26 - 2029/30

* Includes prior approval, certificate of lawful use and reserved matters.

Five year supply assessment measured against local housing need

The five year supply assessment for the area based on the information above is as set out below.

Table 6: Five Year Supply of Deliverable Housing Land

Appendix 1: Windfall

Wellingborough and Kettering

Corby and East Northamptonshire

Notes:

Windfall completions for Kettering 2011/2 - 2022/3 include large sites including Hanwood Park SUE

Appendix 2: Lapse Rates

Wellingborough Lapse Rates:

Notes:

The 120 dwellings that lapsed in 2017/18 were from a single planning application.

The 4081 dwellings that lapsed in 2022/23 were from 3 applications from the SUEs, there are a number of pending Reserved Matters Applications relating to these.

The 163 that lapsed in 2023/4 were from two applications.

Kettering Lapse Rates:

2011/2012 to 2017/2018

2018/2019 to 2024/2025

Notes:

Figures not available for 2023/24 due to a change in monitoring systems.

East Northants Lapse rates:

Corby Lapse Rates:

2013/2014 to 2018/2019

2019/2020 to 2024/2025

2011/2012 to 2017/2018

2018/2019 to 2024/2025

Appendix 3: Housing trajectory

The housing trajectory for the 5 year period.

Last updated 27 October 2025