The rise in house prices is making it more and more difficult for first time buyers to get onto the property ladder.
Buying a first home is now 33% less affordable than it was 10 years ago, according to new research.
By the end of 2004 that figure could increase to 46%, says the research published in Shelter's Roof magazine.
The number of first-time buyers has fallen dramatically over the past two years, indicating the booming housing market could be weakening.
First-time buyers represented only 29% of all buyers last year, compared with 38% in 2002 and 50% in 2001.
Traditionally the disappearance of first-time buyers is a signal house prices are about to slow down.
However, the market has shown fresh signs of growth in the last two months.
The research by Roof suggests the number of buy-to-let investors in the market has bolstered prices.
Yet buy-to-let is the "big unknown factor" and a "volatile dynamic".
"If buy-to-let investors cut and run this could be the catalyst for a severe slowdown," said Roof.
"On the other hand, if existing homeowners continue to see buying another home to rent out as the best investment bet for the future, the gap between housing's haves and have-nots could continue to widen".