Paragon Mortgages, which specialises in lending to professional property investors, has identified the "overwhelming change" in buy-to-let investor behaviour recently.
The lender said a significant proportion of its remortgage business in the last year has been landlords taking mortgages out on previously unmortgaged properties. Before the financial crisis it said remortgage business was primarily the refinancing of existing loans onto new rates.
John Heron, managing director of Paragon, said: "The primary driver of remortgage pre-crisis was churn and the majority of refinancing was moving the loan on to get the client the next best deal.
"The overwhelming change that we have seen since the financial crisis is that a significant proportion of loan applications coming to us today are where the property is currently unencumbered. There is no loan outstanding on the property at all."
Heron said landlords were effectively dipping into their savings in order to release equity for new purchases and gearing up.
And he added: "Or they may well be properties where landlords have used their own cash reserves to effectively bridge their own investment through refurbishment for example, and they now wish to move them onto a mortgage."
Heron said the shift indicated investor confidence in residential property at a time when consumer appetite to borrow was depressed.
"The landlord is a different kettle of fish from consumers and particularly the professional landlord," Heron said.
"Whilst they remain cautious they're still very interested in building up their portfolios, particularly in a property market that is now dominated by very high levels of tenant demand. Selective adding to their portfolios is very much going on."
Remortgaging is around 50% of Paragon's business, which Heron said is similar to the buy-to-let industry as a whole.
