The product is part of its F1 range and priced at 3.39 per cent. It is available up to 75 per cent loan to value (LTV) and comes with one free standard valuation. It is available for purchases and remortgages.
Individual and limited company portfolio landlords are eligible for the mortgage and the maximum loan size is £750,000.
The rental cover requirement is calculated at payrate and stress tested at 125 per cent for limited companies, and 145 per cent for other borrowers.
There is no limit to the portfolio size, but it is subject to a maximum value of £5m with Foundation.
The lender said borrowers were likely to face fewer checks if they gave details of all properties in their portfolio from the outset of the application process.
George Gee, commercial director at Foundation Home Loans, said: “When it comes to portfolio landlords, whether they are refinancing existing properties or adding additional ones, a major consideration is keeping their upfront costs to a minimum.
“Our recent research, in partnership with BVA BDRC, revealed that even with the passing of the stamp duty holiday, a sizeable number of landlord borrowers still intend to add to their portfolios over the coming year, with the average number of properties they intend to buy close to two.
He added: “Portfolio landlord borrowers are also more inclined to use limited company vehicles, and it’s therefore important we continue to offer a range of products which cater for these needs.”