Inspector Roy Foster said he had "severe concerns" about the soundness of Uttlesford District Council’s local plan and advised the authority to start preparing a new document.
Uttlesford District Council’s local plan, which underwent examination earlier in the year, proposes 10,460 new homes up to 2031, or 523 new homes a year.
In a note summarising his conclusions following a hearing session on 3 December, Foster suggested a higher target of 580 homes per year would be more accurate to meet the district’s housing need.
Firstly, he said the plan’s objectively-assessed housing need figure, a key requirement of the National Planning Policy Framework, was not fully compliant with the government’s latest planning guidance.
The Planning Practice Guidance (PPG), according to Foster, states that factors such as affordable housing needs, employment issues and market signals "may require some adjustment" to housing need figures based solely on household projections.
As a result, Foster states that he thinks "an uplift of at least 10 per cent would be a reasonable and proportionate increase in the circumstances of Uttlesford, say to about 580 [homes per annum]".
Foster also criticised a "strategic allocation" in the plan for a new 2,100-home settlement near the village of Elsenham.
It was "not clear", he said, that other "‘new settlement’ options" were considered in a transparent way, while the transport evidence behind the proposal was "inconsistent with the PPG".
Foster stated: "I have severe concerns about the justification for this proposal and thus the soundness of the plan as a whole."
According to the inspector, the scale of work required to address the matters raised would take longer than the maximum six-month period of a suspended examination.
A "revised plan needs to be prepared as soon as possible," he added.
A council spokesman said: "The inspector has indicated that there should be an even higher number of houses than is currently in the plan.
"This is something the council will have to consider, along with the concerns expressed about Elsenham."
The inspector's letter can be found here.
NOTE: This story was amended after publication to make clear that the inspector had not formally found the plan unsound, but had raised concerns about the potential soundness of the document in a note summarising his conclusions.