Kensington Mortgages has pledged to help borrowers with complex circumstances meet the demanding timeframes in the new-build market.
Launching an expanded new-build service, the lender offered clients a day one valuation instruction, new case underwriting within 48 hours and offers within 21 days.
A Kensington spokesman said the self-employed, contractors and borrowers with impaired credit often fell outside the requirements of standard lending criteria when buying new-build property.
Steve Griffiths, sales and distribution director at Kensington, said new build should not be limited to customers who met the standard lending criteria.
He said: "We have worked hard with our key new build distributors since entering the Help to Buy market in 2017 to understand where customers are underserved within the current market.
"Our recent enhancements to our new build proposition ensure that as well as offering great value and criteria, intermediaries can feel confident of the speed of service and consistent lending process that the market requires."
Kensington recently increased its new build loan-to-values on both houses and flats to 90 per cent.
Craig Hall, head of broker relationships and propositions at Legal & General Mortgage Club said getting onto the property ladder could be particularly difficult for customers with complex borrowing needs.
He said: "This is a great step from Kensington, demonstrating its commitment in helping intermediaries find the right solutions for their clients and get the financial support they need."
Earlier this month the Secretary for State for housing, communities and local government created a New Homes Ombudsman to "champion homebuyers" and address quality issues in new homes.