It is not the materials. The data on that is not ambiguous.

No, and the data is unusually clear about it. Over ten years the producer price of paints and varnishes rose +24.5% in nominal terms while consumer prices rose +36.8% — so in real terms paint materials are -9.0%, cheaper than they were. Over the same kind of window, what residential building firms charge for their output is up +21.3% in real terms and the cost of a residential building as a capital asset is up +25.0% in real terms. Materials fell; the job got dearer. It is labour, compliance, finance and time.

The series change with general consumer inflation removed over the identical window: the series change after removing consumer inflation, (1+nominal)/(1+cpi)-1. The deflator is CPI all groups, New Zealand. Real change is computed against the CPI value at the same quarter as the series, so March-quarter series are never deflated by a June CPI. So a series that rose 40% while CPI rose 38% has barely moved in real terms, and one that rose 66% while CPI rose 37% has genuinely got more expensive.

Because an index number on its own means nothing. "1980" is not a price — it is a level relative to a base. Residential building construction (producer price) is based on Dec 2010 quarter = 1000; Residential buildings (capital goods price) is based on Sep 2022 quarter = 1000. Their levels are therefore not comparable to each other at all, only their changes are. Any site that shows you two index levels side by side without their bases is showing you a number it does not understand.

They are a large and measurable part of it. Construction ordinary-time hourly earnings reached $41.41 in the Mar 2026 quarter, up +50.0% in ten years and +9.6% in real terms. That is a real increase, but it is smaller than the +21.3% real rise in what building firms charge — so wage rates alone do not explain the gap. The rest sits in productivity, compliance and consent time, insurance, finance costs, and the cost of supervision and documentation that did not exist at the same intensity a decade ago. Those are not published as a single series, so this site does not pretend to have decomposed them.

The data does not support a timing recommendation and this site will not make one. What it does show is that the last twelve months look different from the decade: residential building construction is -1.6% in real terms over the past year, against +21.3% over ten. A cooling in one year is not a trend, and a renovation decision driven by an index forecast is a bet. Decide on the house, then price it properly.

They measure different things. Property maintenance services is what households pay tradespeople, and it is up +5.5% in real terms over ten years — much less than the +21.3% real rise in what residential building firms charge for their output. Maintenance is a competitive, small-ticket market where price resistance is immediate. Whole-job construction carries the compliance, consent, insurance and supervision load. Renovation sits between the two, which is part of why renovation prices feel unpredictable.