First-time buyers are remortgaging earlier in order to upgrade or extend their properties as soon as they can afford it, a study by IFG Mortgages has found.

"Fledgling" homeowners are leading the trend for early top-up mortgages, according to the brokers.

Over the past year, the average age for purchasing property has not changed, remaining at 34 - including first-time buyers and people trading up.

However, the average age at which people remortgage their property has dropped from 40 to 37, according to a survey of IFG customers.

As house prices have shot up over the past decade, first-time buyers are buying a "basic shell" house then borrowing more as soon as rising property values or their incomes allow them to do so.

The size of the average mortgage top-up loan has also increased from €146,700 in the first half of 2005 to €202,200 in the first half of 2006, a "staggering" rise of 38 per cent, according to IFG, which said the figures suggested that renovation costs have also increased.

"Many other borrowers are feeling the pinch with rising interest rates stretching their ability to service their multiple personal loans, credit cards and mortgage repayments and this is further fuelling demand for remortgages and top-ups," said Shane Connole, head of sales at IFG Mortgages.

"These people are identifying their mortgage as a tool in their financial armoury, which when used carefully can reduce the overall cost of their debt."

Mortgage terms are getting longer as borrowers apply for larger sums to upgrade their properties and roll their short-term personal debts into their mortgage, IFG said.

Growth in first-time buyer business has slowed down, the broker said, as more people are struggling to afford property.