The number of tenants in the UK renting a property with a spare room has nearly halved from 60% in 2010 to just 35% today, the lowest proportion on record according to Countrywide’s latest monthly lettings index.

Also, the extra cost of renting a property with a spare room is now £295 a month, an increase of 14% over the past five years.

“As affordability pressures have risen, for many tenants, extra space has become a luxury,” says its Head of Research Johnny Morris (pictured).

“Sacrificing extra bedrooms and sharing has helped renters to absorb higher prices. But those living in the South are close to a point where there’s not much more room to squeeze, meaning rental growth is likely to be capped by tenants’ incomes for some time.”

The squeeze on affordability in most British cities is also revealed by the research, which says that on average only a quarter of tenants in many urban areas of the south have a spare room including Bristol (24%), Oxford (28%) and Cambridge (27%).

Those tenants living further north are more able to rent a spare room, the research shows, and for example in Liverpool the figure is nearly double at 40% and in Newcastle, 41%.

But the pressures on the rental market may be about to ease in some places. Across England and Wales rents have risen by only 1% over the past 12 months and fell in the South East by 3%. But rents in the Midlands, North and Scotland increased by 2%.