§ Paragraph 28 of PPG3 requires local and unitary development plans to identify sites for housing and buildings for conversion and re-use sufficient to meet housing requirements, after making an allowance for windfalls, and manage the release of land over the plan period. The duration of a plan should be for a period of 10 years from the plan's forecast adoption date. This means plans should make provision for at least ten years' potential supply of housing.
§ Paragraph 34 of PPG3 requires sufficient sites to be shown on the plan's proposal map to accommodate at least the first five years (or the first two phases) of housing development proposed in the plan. This does not mean plans should only have a 5-year time horizon nor is it guidance directed at the determination of planning applications. The purpose is to safeguard against unrealistic windfall allowances. Identifying sites on the proposals map allows allocations to be drawn on expeditiously if the monitoring required by PPG3 demonstrates that windfalls are not being realised as anticipated. If windfalls are being realised as anticipated not all of the sites allocated on the proposals map (which in aggregate provide sufficient capacity to accommodate the first five years or so of housing development) will be needed during the plan's first five years. Managing their release through phasing allows the timely release of sites in support of sustainable development. The aim is to avoid disruption to housing supply, without undermining a plan-led approach to implementing the site search and allocation sequence set out in PPG3.