The National Housing and Planning Advice Unit is advising the Government that at least 2.96 million new homes should be built and as many as 3.48 million may need to be added to the current housing stock.
The group also called on planners and decision makers not to focus on the current short-term downturn in the property market, which is seeing house price falls, but to continue to think about long-term housing needs.
NHPAU chairman Stephen Nickell said: "This is about acting now in advance of the next upturn. It is about ensuring that plans for new homes to be finalised by 2011 cater effectively for people's legitimate expectations and aspirations."
Unsurprisingly, it is southern regions where the NHPAU thinks the greatest number of new homes needs to be built, with it advising that between 486,200 and 622,500 additional properties should be added to the South-east by 2020, as well as between 428,500 and 529,100 in London and up to 486,300 in the East.
The North-east needs the fewest new homes to be built in order for property to become more affordable at between 87,800 and 97,300, while NHPAU advises that up to 283,700 properties should be built in the West Midlands.
The Communities and Local Government team will consider the recommendations when it finalises its own formal guidance to regional planning authorities in its Regional Spatial Strategy reviews, which are due to be completed by 2011.