NZ Building Act 2004 — what you actually have to do about variations.
Plain English. NZ specific. What the Building Act requires for residential building work, when written records are mandatory, and what “in writing” actually means in practice — including whether a voice-capture record like Tydra’s holds up. (Many builders know this as “the CCA”, but the $30k written-contract rule is actually the Building Act — the Construction Contracts Act 2002 is the separate law covering payments and disputes.)
The bits that matter.
The $30,000 threshold
For residential building work where the contract value is $30,000 or more (incl. GST), the Building Act 2004 (Part 4A) requires a written contract that explicitly sets out how variations are dealt with.
Under $30,000
A written contract isn't legally required, but the parties can still be held to whatever was agreed verbally — and disputes over verbal-only variations are where most tradie-customer rows end up.
Commercial work
The Building Act's $30k written-contract rule is residential only. On commercial jobs it's the Construction Contracts Act 2002 that governs payments and disputes — but the variation-record principles below carry over either way.
How a variation has to be recorded.
The Building Act doesn’t prescribe a particular form, but a compliant residential contract (at or above the $30k threshold) has to set out how variations are agreed — and in practice that means each change is recorded in writing, clearly identifying the change, who agreed to it, when, and the cost — or the basis on which the cost will be calculated.
In practice, the parties need a contemporaneous record — meaning the record needs to be made at or near the time the variation is agreed, not three weeks later from memory. This is where most builders trip up: the conversation happens on site, gets verbally agreed, and never makes it into writing until the final invoice.
What a fit-for-purpose record contains.
- A clear description of the change (what work, why, where)
- Who agreed to it (customer name; their representative if a company)
- When the agreement happened (date, ideally time)
- The cost — either a fixed price or a clear basis (e.g. $X/hour + materials)
- Any impact on programme (will it push the completion date)
- Optional but recommended: photo of the variation site (before / after)
Where Tydra fits.
Tydra isn’t a contract template — you still need a proper building contract for residential work over $30,000. But the per-variation PDFs Tydra generates include every element a fit-for-purpose record needs: description, who agreed, when, the cost, optional photos, and (when the customer accepts the bill) their signed acceptance.
That makes it exactly the kind of contemporaneous, in-writing record the Building Act 2004 expects for variations — without anyone having to remember to fill out a form. You talk; Tydra writes it down.
See how Tydra works for buildersCapture every variation, in writing, in the moment.
Voice in, signed PDF out. Stay compliant. Stop arguing at invoice time.