Restrictive monetary policy and the effective collapse of non-bank lending are making an impact on residential investment lending.RBA financial aggregates for March 2008 show the rate of growth in lending to investors fell to 9.5 per cent in March from 10.1 per cent in February, and from 10.5 per cent in January.Growth in investor lending remained in a band between 10.3 per cent and 10.5 per cent from July 2007 to January 2008, and is now beginning to nosedive.Owner-occupied housing growth rates remained relatively stable at 12 per cent.