Heather Cheesbrough, director of planning and strategic transport at the London Borough of Croydon, said the delivery of affordable housing was "a real issue" in her borough, as a substantial part of its supply would be from windfall developments on small sites, such as back garden development.
"Ninety-one per cent of our need is for affordable housing," she told a seminar on densification.
"If we are delivering lots and lots of small sites, the National Planning Policy Framework provides some quite unhelpful guidance saying that you can’t go looking for contributions from sites of between one and nine homes," she said.
"We are very pleased that the London Plan has challenged this and said you should look at your local context."
"This is really important because if we are going to take a higher housing target from the London Plan, approximately 50 per cent of our housing growth will come from windfall suburban site situations," Cheesbrough said.
"We will not be able to deliver affordable housing need if we cannot have contributions from smaller sites."
Cheesbrough added that the requirement for significantly higher housing targets from the new London Plan could make it difficult for London boroughs to meet the housing delivery test. The test measures new homes delivered against the local housing requirement, with penalties for councils failing to meet certain thresholds.
Meanwhile, Andy von Bradsky, architectural and built environment advisor at the Ministry of Housing, Communities and Local Government, told the seminar that the government was currently in the process of rewriting the design sections of its Planning Practice Guidance.
"We will be developing this over the next few months, and will be launching the new guidance in the spring," von Bradsky said.
Key challenges for councils in pushing for greater densification would include applying such policies to rural contexts and securing community support for densification, von Bradsky said.