It was also found that Londoners have the highest expectations of cost, with 24 per cent believing the work would cost over £25,000 to carry out.
Forty per cent of people in the north-east said they thought it would cost between £5,000 and £10,000 to carry out.
Mark Boyle, personal loans manager at Alliance & Leicester, said: "Homeowners may want to consider taking out a personal loan to fund loft conversions and other home improvements to add long-term value to their property."
He added that homeowners should ensure they shop around for the best deal they can find.
Meanwhile, the National Energy Saving Trust has recommended cavity and loft insulation as one of the best ways to cut down on energy bills and save money.
The trust estimates that around 50 per cent of a house's warmth is lost through its walls and roof.
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