Of the £319.4m, £197.8m was categorised as bridging loans – a 19.6% increase from the previous quarter.
The three months also saw ASTL members exceeding £1bn in completions for the first time, with annual completions in bridging lending passing £3.5bn last year.
The trade body said the figures highlighted a growing trend for property developers to rely on short term lending.
Benson Hersch, chief executive officer of the ASTL said: “The housing crisis continues to be high on the government’s agenda and Sajid Javid highlighted last year that he wanted to do more to support SME building firms. Increasingly these small developers are relying on short term funding solutions, because traditional forms of finance are often not available to them.
“Such a trend demonstrates how alternative forms of finance are providing the solutions where the government and the banking industry should be and could be bridging the gap.
“These figures are taken from the responses from ASTL members, which include most of the key lenders in the bridging market.”