At least 505,500 homes need to built in the east of England by 2021, according to a government report.
The report, published on Thursday, calls for the expansion of Colchester, Ipswich, Norwich and Thetford.
It also calls for the growth of Hemel Hempstead, Welwyn Garden City and Hatfield, which council bosses have described as "not logical".
The number of extra homes in the region called for has increased by 27,500, from the 478,000 in a draft plan.
It includes proposals to expand Chelmsford and green belt reviews carried out in Stevenage and Harlow.
The Government Office for the Eastern Region report will be considered by the government, which will publish a finalised plan next year.
Following the report's publication, the East of England Regional Assembly (EERA) called on the government to recognise the limits of housing growth and provide the funding for infrastructure necessary to support it.
The 27,500 increase includes an extra 4,600 homes for Bedfordshire, 9,000 for Cambridgeshire, 1,100 for Essex, 3,600 for Hertfordshire, 6,100 for Norfolk and 3,100 for Suffolk.
John Reynolds, chair of EERA's regional planning panel, said: "The region has a significant housing shortage and we need to increase provision over the next 15 years to ensure that present and future generations have the opportunity to own a home."
The government panel report concludes: "The spectre of 'concreting over' the countryside is a gross exaggeration which has no place in serious debate.
"As anyone who knows the region or who explores it as we have done will be aware, the East of England has very extensive tracts of country.
"Far and away the majority of its physical area, which is beautiful, productive and under no threat of urban development either now or in the future."
Hertfordshire County Council criticised the increase in the number homes planned for the county from 79,600 to 83,200.
Council leader David Beatty said: "We just don't understand the logic of this extra increase.
"We have repeatedly voiced our concerns about the impact large-scale development will have on our services and the infrastructure of the county, but not only have those concerns been ignored they have been walked over.
"No provision at all has been made for the extra pressure on roads and transport, education, health and water services, and it rides roughshod over our greenbelt."