National policy supports making effective use of land, but retains tests protecting access, character and living conditions. [1]
What the different descriptions mean in practice
For a backland proposal, begin with the route between the street and the new homes. Test emergency access, refuse collection and the effect of entrances and windows on the surrounding gardens. A generous building area is of limited use if these routes cannot be made workable. [2] [3] [4]
For an infill proposal, compare the gap with the buildings on either side. Sections showing heights, window positions and levels can reveal constraints that a plan alone conceals. The design should explain its relationship to the street rather than assume that any gap should be filled completely. [4]
For a corner proposal, test both street frontages. Policy L2 in the NPPF published on 17 August 2026 recognises that street corners can offer opportunities for higher buildings, but does not remove the need to assess character, safe access and amenity. [1]
For a garage or other previously used site, establish its physical condition and previous activities. Under policy P2, contamination and ground stability must be addressed where relevant. A cleared surface does not itself demonstrate that land is suitable for a home. [5]
Test the things that can change the layout
Prepare an initial constraints plan before choosing a unit count. It should bring together:
- the building envelope, neighbouring windows and usable external space;
- existing trees, potential habitat and any necessary ecological investigation;
- entrances, accessible routes, emergency access and collection arrangements;
- water and drainage connection points and the routes needed to reach them. [4] [6] [2] [3] [7]
Then test furnished floor plans. Minimum room and dwelling areas are not interchangeable: a flat can have an adequate total area but a bedroom that is too narrow, or a layout that does not work for its intended occupants. [8]
Check delivery, not just the planning drawing
A drainage proposal should identify the actual connection point, pipe sizes and levels. Thames Water asks for this information when considering sewer connections. Where a connection crosses someone else's land, its process also requires the relevant permissions; a planning layout should not simply assume that route is available. [7]
Compare options that address the same constraints differently. For example, test whether reducing height, changing window orientation or altering the number of homes produces a more credible layout. [4]
Current policy and forthcoming guidance
London's approach is design-led: site capacity should emerge from context and housing quality. The draft London Small Site Design Code, under consultation until 4 December 2026, may provide further guidance but was not adopted on 2 October 2026. Its proposals should therefore be identified separately from the rules used to support an application today. [4] [9]