Coventry Building Society increased its gross mortgage lending by 33% to £2.5bn in the first six months of this year.
Profit before tax increased by 17% to £52.8m and the mutual increased its mortgage assets by £1.8m to £21bn.
The third largest mutual increased its savings balances by £300m to a record £19.3bn and reported a Core tier 1 ratio of 21.9%.
The society said in H1, net interest income increased by £8.1m reflecting the benefits of recent growth. On impairments, at 30 June 2012, 0.80% of mortgage balances were 2.5% or more in arrears, and impairment charges totalled £4.3m from a loan book of £21bn.
The society said: "Throughout the financial crisis, we have sustained a consistent appetite for new mortgage lending and market conditions continue to favour our business model. Gross mortgage advances totalled £2.5bn, representing 3.8% of new mortgages in the UK and just over 18% of all mortgage lending undertaken by building societies and mutual banks."
David Stewart, chief executive, commented on the results: "Coventry continues to make strong progress, building on the excellent record established since the onset of the credit crisis. Coventry is now the only rated UK high street bank or building society not to have been downgraded by any rating agency in any of the last three years.
I remain confident that the Society is well positioned to continue to prosper in what is still an uncertain economic environment."
Coventry completed its first public residential backed securitisation in May 2012, which raised £800m of term funding, after successful issuances of long term unsecured bonds in 2009 and 2010, worth total £750m and covered bonds totalling over £1.2bn issued in 2011.
Coventry also bought a £0.5bn loan book comprising UK buy-to-let mortgages originated by Bank of Ireland's UK businesses.
Kevin Purvey, head of intermediary sales at Coventry said he expects more of the same for the rest of the year with buy-to-let playing a large part in its residential lending plans.
"It has certainly been one of the bright spots in the market as people choose to rent or are forced to delay purchase."