The fall was more pronounced in England which dropped 4% as public housing start suffered the jitters amid Government policy changes.
Across the UK private sector home registrations remained largely flat at -1% (28,527; 28,906 in 2014), while the public sector dropped 4% (7,692; 8,049 in 2014).
Experts in the housing industry blamed the drop in public new home to many housing associations holding back on developments in light of welfare reforms and the cap on rental increases.
Overall year-to-date figures up to the end of September show that the number of homes registered with NHBC was 9% higher than the same time last year (117,525; 108,118 in 2014).
The new statistics also show that London bounced back with a 25% rise in the number of new homes registered during Q3 (7,289; 5,812 in Q3 2014).
But Yorkshire & the Humber and the West Midlands suffered big falls, down a third and a quarter respectively.
NHBC Chief Executive Mike Quinton said: “Despite the marginal drop in housing registrations this quarter, 2015 is still promising to be a strong year for new housing growth in the UK.
“The industry remains upbeat and is working hard to build the number of homes our country so desperately needs, despite the pressures associated with rapid growth.”