The new loans include a two-year 75 per cent loan to value (LTV) fixed rate residential mortgage at 1.94 per cent.
The building society has also launched a five-year fixed rate residential mortgage with 95 per cent LTV fixed at 3.94 per cent which is particularly aimed at first-time buyers.
Both new mortgages have no product or application fees, £500 cashback on completion and are available on new build properties, with a 28-day "application to offer" turnaround.
Ray Boulger, senior mortgage technical manager at John Charcol, said: "Although lower rates are available elsewhere once the overall package is taken into account both these products are competitive, particularly for smaller mortgages.
"The cash back will be particular welcome for 95 per cent LTV borrowers and Leek is one of the few lenders which makes its 95 per cent LTV mortgages available for new build properties."
Homebuyers can also make 10 per cent overpayments each year without incurring any penalties.