8.31 National planning policy[1] provides an indicative minimum site size threshold for the provision of affordable housing of 15 dwellings, however it also accepts that local planning authorities can set lower minimum thresholds where viable and practicable i.e. such smaller sites will cumulatively deliver more affordable homes. The Strategic Housing Market Assessment indicates that, in light of the evidence gathered, a case can be made for a general threshold of 10 dwellings on supply and viability grounds in South Somerset. Any lower threshold would require further evidence of likely provision forthcoming from both market sites and viability of smaller sites before it could be justified.

8.32 Additional data analysis of past completions[2] and where those completions (on smaller sites) have occurred has been undertaken and the findings are set out in the tables below:

8.33 The analysis demonstrates that on average over the last 5 yrs over half of the dwellings completed each year in Rural Settlements have been delivered on sites of 1-4 dwellings. This evidence would therefore confirm that in order to maximise the delivery of affordable housing the threshold should be set as low as possible and that such low thresholds will indeed deliver cumulatively a significant number of affordable dwellings. However, whilst a low threshold can be justified numerically it also has to be viable, so additional viability assessment work has been undertaken.[3] The updated assessment builds on the work previously undertaken for the SHLVA by considering the viability of 8 smaller sites of between 3 and 12 dwellings and, in order to provide a basis for comparison, the 6 South Somerset SHLVA sites were updated to April 2010 market conditions. For consistency the same development assumptions were used as in the original SHLVA. The findings show that in current market conditions (April 2010) a threshold of 6 dwellings would be viable in general terms across the District.