The lack of new homes being built is predicted to send rents soaring by up to 48% across parts of the South West by 2020, leaving thousands forced to rely on housing benefits, a new report warns.
The cost of renting an average home is expected to surge to £1,064 in some areas, a rise of £347 a month, according to the National Housing Federation.
It says years of not building enough homes has created an unsustainable housing market which could see thousands more of the region's families relying on Government support to pay their rent in the next few years.
Home Truths 2012 found that the future of the housing market is looking even bleaker than was thought, with both private rents and house prices set to move further out reach of ordinary families.
Jenny Allen, South West lead manager for the NHF, said successive governments had failed to tackle the under-supply of housing and time was now running out.
Ben Bradshaw, former Labour cabinet member and MP for Exeter, where average monthly rents are set to rise £347 a month to £1,064, blamed the Coalition. He said the findings would "horrify" a growing number who rent because they can't afford to buy.
"The building of new affordable housing for rent has collapsed under this Government," Mr Bradshaw added.
"We already have the biggest gap in Britain between wages and housing costs and this is set to get worse because of this Government's policies.
"It is a scandal that, in effect, the taxpayer will find themselves subsidising extortionate rents through housing benefit. It would be much better to spend that money building the new homes we so desperately need."
Across England, the cost of privately renting a home has already risen by 37% in the past five years, and is set to soar a further 35% over the next six. Levels are predicted to remain stable through next year, but could see steep increases from 2015 to 2018 of around 6% a year as interest rates rise and house prices increase.
Some 417,830 more working people, an 86% increase since 2009, are now reliant on housing benefit, a figure expected to climb as austerity bites harder and rents outstrip stagnating earnings.
The analysis puts the South West fourth in the country and ahead of the national average (47%). The steepest annual increase in the region (7.6%) is predicted to come in 2016.
A second study, by the Council of Mortgage Lenders, found sharp rises and falls in house sales.
Ivybridge saw a 43% increase, Redruth sales were up 40% but Truro dropped 20%.