You have found unconsented work. Now what?

It usually surfaces one of two ways. A builder opens a wall and finds framing that matches nothing on the property file, or a lawyer reading a LIM before a sale asks a question nobody can answer. Either way, the conclusion is the same: at some point in this house's life, someone did building work that never went through council.

First, breathe. This is common. A large share of the older homes we open up have something in them that was never consented: an enclosed porch, a moved wall, a bathroom that migrated in the eighties. Common does not mean harmless, but it does mean the paths forward are well worn. The options are narrower than people hope and wider than they fear.

First, establish what you actually have

Before choosing a path, you need three facts. What exactly was done. Whether it was done adequately. And whether it needed consent at all when it was done, because some work is legitimately exempt under Schedule 1 of the Building Act and the fix there is documentation, not council.

This usually means getting the property file from council and comparing it with the physical house, then having someone experienced look at the work itself. The file is cheap to order and often surprisingly complete, and it sets the baseline: everything in the house the file cannot explain goes on your list to understand. Sometimes that involves opening things up, which is exactly the kind of paid investigation we do before pricing any renovation, and it earns its keep double here: the same look that scopes your renovation also scopes your unconsented-work problem. Well-built unconsented work and badly built unconsented work are entirely different situations, and you cannot tell which you have from the paperwork alone.

The Certificate of Acceptance route

The formal mechanism for unconsented work is the Certificate of Acceptance, or COA. It is council's way of retrospectively recognising work that should have had a consent, by stating that, so far as council can reasonably ascertain, the work complies with the Building Code.

That phrase 'so far as council can reasonably ascertain' carries the whole difficulty. Council was not there when the work was done. It never inspected the foundations before the pour or the framing before the linings went on. So a COA process runs on evidence: what can be seen, what can be opened up for viewing, what reports from engineers and other professionals can establish. Where the evidence cannot be produced, council can exclude elements from the certificate or decline it.

• A COA is slower than a consent for equivalent work, because the process runs backwards. You are reconstructing a story council would normally watch unfold, and every gap in the story needs filling with reports, openings or both.
• It is not guaranteed. Council can decline, or can issue a certificate with elements carved out, and a COA with exclusions on it answers some of a future buyer's questions but not all of them.
• It is rarely just paperwork. Expect some opening up so work can be viewed, and expect to fix anything found wanting along the way. The COA often becomes a small remediation project with a certificate at the end.
• It is still usually worth doing. A house with a COA is a house with an answered question. A house with known unconsented work and no paper trail carries that question into every future sale, loan and insurance conversation.

Go into a COA application knowing what feeds it. Council will want whatever makes the invisible visible: photographs from when the work was done if any exist, invoices and product records, reports from a structural engineer or other specialists, and physical opening up so an inspector can view framing, fixings or waterproofing that would normally have been inspected in sequence. The stronger that bundle, the shorter the argument. The applications that go well are the ones treated as evidence-gathering exercises from the start, not as a form to lodge.

Set expectations on time and cost accordingly, in relative terms. A COA generally costs more in fees than the original consent would have, takes longer, and carries the cost of the reports and the opening up on top. That arithmetic belongs in front of you when choosing between a COA, a rebuild under consent, or renegotiating a purchase, because the right answer differs job by job and the arithmetic drives it.

The other paths, honestly

A COA is not always the right answer. If the work is poor, the honest fix is sometimes to remove or rebuild it properly, under a consent this time, which gives you a normal consent and CCC at the end instead of a qualified certificate. If the work turns out to have been exempt under Schedule 1 all along, the fix is a well-documented file establishing that, and council need not be involved. And if you are buying rather than owning, the existence of unconsented work is a negotiation fact: it affects value, and it is far cheaper to resolve before settlement, with the vendor's participation, than after.

Buyers hold one more card owners never do: conditions. If a building report or LIM turns up unconsented work before you go unconditional, you can make the contract conditional on the vendor sorting it, price the risk into your offer, or walk away entirely. All three are stronger positions than any owner ever holds, which is why the best moment to deal with unconsented work is, ideally, while it is still someone else's.

The path people hope exists, quietly ignoring it, is the one we would talk you out of. Vendor disclosure obligations, sharp-eyed building inspectors and LIM reports mean unconsented work almost always surfaces eventually, and it surfaces at the worst time: mid-sale, with a deadline, when every fix costs more and every option is narrower.

The pattern across all of it: unconsented work is a problem that shrinks when you walk toward it. Establish what you have, get honest advice on which path fits, and start the process at a time you chose rather than one a sale forced on you. Almost every version of this story ends fine. The expensive versions are the ones that started late.