Consents to build new houses fell 12.2 percent in September and, for once, it could not be blamed on volatile numbers of consents to build apartments.
Excluding apartments, consents were down 10.4 percent, adjusting for seasonal variations.
The Government Statistician, Liz MacPherson, said the trend in consents was now easing but was still about 10 percent higher than a year ago.
Westpac economist Michael Gordon said it was possible people were deferring decisions about building in the lead-up to the general election.
"I suspect this is more issues with timing rather than telling us anything fundamental about what's going on in the building industry."