Auckland · 2026 Edition
What We Find Behind the Walls, and What Counts as a Variation (2026)
A fixed-price renovation covers everything that can be seen and measured before work starts. A variation is a change to that: something you ask to add, or damage nobody could see until a wall or floor was opened. The common finds in Auckland homes are rot under showers and joinery, borer, old wiring and asbestos.
“Is it a fixed price contract? What kind of things make a variation?” is one of the first questions we hear. Hidden damage came up in 24 of 69 recent consultations, and quotes and variations in 29. One owner put it well: “It’s hard to know ahead of time when you don’t know what’s behind the wall.” This guide shows six things our site teams found this year, what happened next on each, and the rules we work to when it happens on your job.
The short answer
We quote a fixed price. That price holds for the work written in the scope. It changes only through a variation, and a variation goes ahead only after you have approved it in writing.
| What we work to | At Add Value Renovations |
|---|---|
| Type of quote | Fixed price |
| How a variation is priced | At cost plus a 20% margin |
| When variation work starts | After you approve it in writing |
| Contingency | Not in the total. Shown as an indicative allowance of about 10% of the trade subtotal |
| Defects period | 24 months |
| Guarantee | Master Build 10-Year Guarantee on residential contracts of $30,000 or more |
What a fixed price includes, and the two kinds of variation
A fixed price means you pay the agreed amount for the agreed scope, whatever it costs us to deliver it. The scope is the written list of what is being built, room by room and trade by trade. If we could see it and measure it before we priced the job, it belongs in the price. Our post on fixed price versus charge-up explains why we work this way.
A variation is a change to that scope. There are two kinds, and they feel very different when they happen.
| A change you choose | A hidden condition | |
|---|---|---|
| Where it comes from | You ask to add, remove or upgrade something after signing | Something is found once a wall, floor or ceiling is opened |
| Examples | A different tile, an extra window, more power points | Rot, borer, wet framing, asbestos, a damaged bearer |
| Could it be priced beforehand? | Yes, if it had been decided before signing | No. Nobody could see it |
| Who decides | You | You, once you have seen the photos and the price |
The first kind is in your hands. Decide as much as you can before you sign and there is little left to vary. The second kind is the one people worry about, so here is what it looks like on real jobs.
Six things we found this year
These come from our own site records for 2026. We have left out the suburbs and anything that would identify the homes. We have also left out prices: each fix is priced on what is found, and a figure from one house would mislead you about yours.
1. Water-damaged floorboards under joinery
During the strip-out on a full home renovation, the team uncovered water-damaged floorboards under the window and door joinery. Joinery here means the window and door units themselves. The boards were covered until the strip-out reached them, so there was nothing to see at the quote stage. Work on those boards stopped, and we needed the owner’s approval before any of them were removed.
2. Borer behind a living-room wall lining
On an extension and renovation, borer was found behind the living-room wall once the lining came off. Borer is a small beetle whose larvae tunnel through timber, and over many years it can weaken the wood. From inside the room the wall looked sound, because the damage was on the framing side of the lining. The timber was treated, and extra insulation went into the wall while it was open.
3. A damaged bearer picked up at a council inspection
A bearer is a heavy timber beam that sits on the piles under a house and carries the floor joists. On one job this year, the council inspector raised a damaged existing bearer during the framing stage. It was part of the old house, under the floor, where nobody sees it day to day. The earliest re-inspection slot was a week away, and the programme slipped by four working days.
4. Asbestos that put a job on hold
During demolition on a renovation, asbestos was found and the job was put on hold. Asbestos is a mineral fibre that was used in many building products, and homes built before 1 January 2000 may contain it. You cannot confirm it by looking; a suspect material has to be sampled and tested by a laboratory. Once it is found, the affected work stops and people are kept away until it has been assessed and dealt with by the right specialist. Our asbestos removal guide covers the full process.
5. Wet framing that had to dry before lining
Before the wall linings went on at one job, moisture readings on the framing were too high to close the walls in. Framing is the timber skeleton inside a wall, and its moisture can only be measured once the timber is exposed. Fans were run for several days, and the linings went on only after the readings had come down. Lining over wet timber traps the moisture inside the wall, so this is a step that cannot be hurried.
6. A beam needed once a wall was opened
On a bungalow renovation, opening up during demolition showed that a beam was needed above a bedroom wall. What holds up a ceiling or roof is hidden above the linings, and old houses do not always match what anyone expects. The beam had to be worked out, priced and approved before work on that wall could carry on.
The pattern across the six is plain. Most hidden finds are timber problems: boards, bearers, framing and borer. None of them could be seen at the quote stage, and none of them meant the builder or the owner had done anything wrong.
How a variation is handled
When something like this turns up on one of our jobs, the steps are always the same.
- Work stops on that item. The rest of the job carries on where it can.
- It is photographed. You see what we see, even if you are not on site.
- It is priced. At cost plus a 20% margin.
- You approve it in writing. Nothing is done on a handshake or a phone call alone.
- Then the work is done. Not before.
Every variation carries a clear title and a reason for the change, so that months later you can read the list and know what each one was for. If a builder does the work first and sends the bill afterwards, you have lost your chance to say no. Our post on what a renovation contract should include sets out the variation clause to look for, and how we manage your renovation shows where this sits in the wider job.
Why we publish the margin
Variations are where trust is won or lost on a building job. A builder who quotes low and makes it back on variations has every reason to find them. We charge cost plus 20% on every variation, and we would rather you knew that before you sign than found out halfway through.
How to lower the risk before signing
You cannot remove the risk of hidden damage in an older house, but you can shrink it. These checks are worth doing before the price is set.
| Check | What it tells you |
|---|---|
| Asbestos test | Whether older vinyl flooring, textured ceilings or other suspect materials in the work area contain asbestos. A test only clears the material sampled. |
| A look under the floor | The condition of the piles, bearers and joists, and any signs of damp or borer, where there is room to get under. |
| The council property file | The plans and records the council holds for the house, which you can compare with what is there today. |
| A small inspection hole | Where a leak is suspected, a small opening in the lining shows the timber behind it before the price is fixed. |
For asbestos, our published guide gives indicative allowances of $80–$180 for each test sample and $400–$1,000 or more for a renovation survey. These are market allowances, not quotes; confirm with the provider what is included and whether GST is on top.
The other half of the job is yours: make your selections before you sign. A tile, a tap or an oven chosen after the contract is signed is a change you chose, and it is the kind of variation you can avoid altogether. Our post on why renovation budgets blow out goes through this in detail.
How much contingency to hold
Contingency is money set aside for things nobody could see. We do not price it into your total. We show it beside the quote as an indicative allowance of about 10% of the trade subtotal, which is the trade work in your quote added together.
That allowance is a guide for your own planning, not a charge. You pay only for variations you have approved, at what each one actually comes to. If nothing is found, none of it is spent. An older house carries more risk than a newer one, so if your home has had leaks or has never been opened up, plan to have more in reserve.
Hidden damage and variation FAQs
Only through a variation. The fixed price covers the written scope, so the total changes when you ask for something different or when hidden damage is found that nobody could see beforehand. On our jobs every variation is priced and approved by you in writing before the work is done.
Yes. Work stops on that item, we photograph it and price it, and nothing goes ahead until you have approved it in writing. Your contract should say this in plain words; if it does not, ask for it to be added before you sign.
Cost plus 20%. That applies to every variation, whether it is a change you asked for or hidden damage. Each one has a clear title and a reason so you can check it later.
We show an indicative allowance of about 10% of the trade subtotal. It is not part of your total and is charged only as variations you approve. Hold more in reserve for an older house or one with a history of leaks.
It depends on what the inspector has found. Damage in the existing house that nobody could see, like the bearer in our example, is handled as a variation in the usual way. A fault in our own work is ours to put right. Whether your job needs a consent at all is covered in our building consent guide.
Some of it can. An asbestos test, a look under the floor, the council property file and a small inspection hole where a leak is suspected all reduce the unknowns. They cannot show everything, because most of a house’s timber stays hidden until linings come off.
It can. On one job this year a damaged bearer raised at a council inspection moved the programme by four working days, because the earliest re-inspection was a week away. Ask what a variation does to the programme when you are given its price.
Our defects period is 24 months, so we come back and put right defects in our work that appear in that time. The usual period in New Zealand contracts is 12 months. Residential contracts of $30,000 or more also carry the Master Build 10-Year Guarantee.
Planning a renovation and worried about surprises?
A 30-minute phone call with us covers what to check before you sign anything.
Book a free phone consultation →
