Affordable Housing Supplementary Planning Document 2012-2027

Purbeck’s affordable housing Supplementary Planning Document (SPD) was adopted on 9 April 2013. Please also see:

The SPD builds upon and provides further detailed advice and guidance on housing policies in the Purbeck Local Plan Part 1 (2012) including policies AH (Affordable Housing), AHFT (Affordable Housing Tenure) and RES (Rural Exception Sites). The SPD also includes guidance relating to self-build rural exception sites.

On 18 July 2024 Dorset Council adopted the Purbeck Local Plan (2018-2034) which formally replaces the Purbeck Local Plan Part 1 (2012) for this part of Dorset Council area. Following adoption of the new local plan, the Purbeck Local Plan Part 1 (2012) no longer forms part of the development plan for this part of Dorset.

The new local plan includes policies relating to affordable housing (Policy H11) and rural exception sites (Policy H12). Paragraph 193 of the new local plan specifically relates to Policy H11 and states:

‘The Council's method for calculating commuted sums for affordable housing takes account of the housing sub-market area, the number of affordable homes that are being sought and the size of the smallest market homes in the development that will be built if the Council grants planning permission. The amount of a commuted sum depends on the number of bedrooms in a property. For the avoidance of doubt, the Council will consider rooms that have the potential to be a bedroom (e.g. playroom or study) to constitute a bedroom for the purposes of the commuted sum calculation. The Council's website provides full step-by-step guidance on how to undertake this calculation.’

We are working on new step-by-step guidance for commuted sum calculations across Dorset which can also be applied in Purbeck for Policy H11 and will consider whether separate detailed advice and guidance is still needed in respect to Policy H12 and self-build rural exception sites.

Pending publication of the new guidance we will be relying upon the existing affordable housing contribution values for the Purbeck area set out in How to calculate the contribution for affordable housing as part of a planning application (dorsetcouncil.gov.uk) when calculating commuted sums as part of the application of Policy H11. (Commuted sums will be calculated using the most up to date step by step guidance in force at the time a decision is taken to grant permission subject to a s106. Sums will not be recalculated to take account of new guidance other than at the applicants’ request prior to the completion of the s106).

Under policy H11 of the Purbeck Local Plan the process for identifying affordable housing commuted sum contributions is as follows:

Table showing the process for calculating a commuted financial sum for affordable housing referencing both Policy AH from the Purbeck Local Plan Part 1 (2012) and Policy H11 from the Purbeck Local Plan (2018-2034)
Steps set out in guidance note dated 2 April 2013 for policy AH: Steps to be followed under policy H11:
  2-9 homes
(does not apply to sites in Lytchett Minster, Upton and Wareham Town Council areas) 		 10+ homes
Applies to all development in the Purbeck Area
 
1 - Identify the housing sub-market 1 - Identify the housing sub-market using Map 1 (page 2 of 2013 guidance)
Unlike Policy AH in the Purbeck Local Plan Part 1, this no longer influences the percentage requirements which are set out in emerging policy H11, but will influence contribution values used. 
2 - Calculate the number of affordable homes Policy H11 requires 20% for 2-9 homes For 10+ homes policy H11 requires
40% on greenfield sites
30% on brownfield sites (definition of brownfield provided by the NPPF)
3 - Choose the dwelling size 3 - Choose the dwelling size 
Choose the house size in Table 1 on page 4 that corresponds to the smallest market home that will be built if planning permission is granted. Rooms that have the potential to be a bedroom should be included.
4 - Choose the correct table 4 - Use Table 1 and follow the instructions at Step 4a (page 4 of the 2013 guidance)
Please note that the figures in Table 1 relate to 0.1 of a unit. So, if there was a net increase of 6 dwellings then 20% would require 1.2units and 12 x figure given in the table.
5 - Agreement with the Council 5 - Enter into agreement with the Council to secure the affordable housing contribution (legal costs for the drafting of the s106 will need to be paid by the applicant). Or 
Provide a viability assessment to demonstrate that the contribution would make the scheme unviable. The Council will undertake an independent assessment of your development scheme using the District Valuer who charges a fee which will be passed to the applicant.