Many smaller housebuilders will be hit by the government's insistence that social housing be included on small estates, a seminar heard last week.
Speakers warned a Planning and Development Association meeting that small and medium-sized housebuilders would be badly affected by plans in the draft Planning Policy Statement 3 to make 15 dwellings the threshold for a social housing contribution.
Planning consultant Roger Humber said: "It's going to have a big impact on the viability of the small and medium-sized building sector."
Les West, Barton Willmore Planning Partnership director, echoed Humber's concerns. He said: "It puts an undue burden on small sites. It will kill off another delivery vehicle that will affect overall supply."
The association's draft response to PPS3, drawn up after last week's meeting, underlined the warnings expressed at the seminar.
PPS3 will kill off another delivery vehicle
Les West, Barton Willmore
It said: "The reduction in the threshold to 15, with the possibility of allowing councils to reduce it further, will inevitably put pressure on the viability of smaller sites.
"At a time when policy is seeking to identify more developable sites and still to maintain the brownfield first strategy, this seems perverse."
West also expressed concern that the government had reneged on previous commitments to stop councils telling housebuilders which registered social landlords they could work with.