Planning a renovation budget and choosing trades

Most renovations that go wrong do not fail because of one big mistake. They drift: the scope grows, a hidden problem turns up behind a wall, the tiler is booked before the plumber has finished, and the money runs out before the finishing touches. Good planning will not remove every surprise, but it will make surprises manageable.

This guide walks through the order we would suggest for planning a renovation in New Zealand: scope, budget, contingency, sequencing, the rules around licensed trades and contracts, and consents.

Start with scope, not finishes

It is tempting to start with the fun part: tiles, tapware, paint colours. Resist it for a little while. The single most important document in any renovation is a clear scope: a written list of what is being changed, what is staying, and what is out of bounds.

A useful scope answers questions like these:

• Which rooms are affected, and what is the end result for each?
• Are any walls being moved, removed or added?
• Is plumbing, drainage or wiring moving, or only being replaced in place?
• Are windows, doors, cladding or the roof involved?
• What must be finished by a certain date, if anything?
• What are you deliberately not touching this time?

Write it down, then share the same scope with everyone you ask to quote. If each trade prices a different version of the job, the quotes cannot be compared.

If each trade prices a different version of the job, the quotes cannot be compared.

Building the budget

Break the budget into categories rather than one big number. A typical split includes design and documentation, consent and council fees, demolition and disposal, structural and building work, plumbing and drainage, electrical, wet-area waterproofing, linings and stopping, joinery and cabinetry, fixtures and fittings, flooring, painting, and cleaning and making good.

Get at least rough figures for each line before you commit. Fixtures and finishes are where budgets most often creep, because each individual upgrade looks small. Decide early which items are fixed and which are "nice to have if money allows".

Contingency

Set aside a contingency, separate from the main budget, for things nobody could see at quoting time. As a general guide:

• 10-15% for a straightforward job in a newer house with good documentation.
• 15-20% for older houses, bathrooms and kitchens, where rot, leaks, old wiring or uneven floors are common discoveries.
• 20% or more for villas, bungalows and houses with a known history of weathertightness issues or past unconsented work.

Treat contingency as money for problems, not upgrades. If you reach the end with some of it unspent, that is the time to add the nicer tapware.

Sequencing the work

Renovation trades follow a fairly predictable order. Getting it wrong costs time and often money, because work has to be undone.

1. Design, scope and consent (if needed).
2. Demolition and strip-out, then a pause to look at what has been uncovered.
3. Structural and framing work, including any new openings or walls.
4. Rough-in services: plumbing, drainage, electrical and ventilation inside the walls.
5. Inspections, if consented, before anything is covered.
6. Insulation and linings, then stopping.
7. Waterproofing in wet areas, followed by tiling.
8. Joinery and cabinetry, benchtops and splashbacks.
9. Fit-off: plumbing and electrical fixtures.
10. Flooring, painting and finishing, then a final clean.

Build buffer time between stages, especially after demolition and before waterproofing. Long lead times on joinery, benchtops and imported fixtures can quietly set the whole schedule, so order early.

Licensed Building Practitioners and restricted building work

In New Zealand, some residential building work is classed as restricted building work. Broadly, it covers work that is critical to the structure and weathertightness of a home, such as foundations, framing, roofing and cladding, along with the design of fire safety systems in some small-to-medium apartment buildings. This work must be designed and carried out, or supervised, by a Licensed Building Practitioner (LBP) with the right licence class. Building.govt.nz explains what counts in its guide to restricted building work.

When restricted building work is done, the LBP who designed it provides a certificate of design work, and each LBP who carried out or supervised it provides a record of building work. Keep copies with your house records. Plumbing, gasfitting, drainlaying and electrical work have their own separate licensing systems, so check that those trades hold the right registration too.

Comparing local trades

When you are comparing local trades, ask at least two or three for written quotes against the same scope, and check that each quote spells out what is included, what is excluded and how variations will be priced. Look up builders and designers on the public Licensed Building Practitioners register to confirm their licence class is current, and check plumbers and electricians on their own registers. Ask for two or three references from recent jobs of a similar size, and if you can, talk to those homeowners about communication, tidiness and how problems were handled. Finally, insist on a written contract that sets out the price or pricing method, the timeline, payment stages and how disputes will be resolved, even for smaller jobs where it is not legally required.

Written contracts and the Building Act requirements

Under the Building Act, residential building work priced above a threshold set in regulations must have a written contract. For work at or above that threshold, the contractor must also give you a prescribed disclosure statement and a standard checklist before the contract is signed. The disclosure covers the contractor's details, experience and insurance, and the checklist explains your rights and the contract process. You can ask for the disclosure and checklist for smaller jobs too. Building.govt.nz sets out the current threshold and requirements in its page on why contracts are valuable. Check the figure there rather than relying on memory, as regulated amounts can change.

Regardless of price, the Act also gives homeowners implied warranties on residential building work and a defect repair period of 12 months after completion, during which the contractor must fix defects you notify in writing.

Consents

Many renovations need a building consent from your council before work starts, particularly anything that changes structure, adds or moves plumbing and drainage, or affects weathertightness. Some lower-risk work is exempt under Schedule 1 of the Building Act, but exempt work must still comply with the Building Code. If you are unsure, ask your council or a designer before you book trades. Resource consent under district plan rules is a separate question, and may apply to things like additions near boundaries or changes in heritage areas.

Allow time for consent processing in your schedule, and remember that a code compliance certificate is issued only after final inspections. Work done without a required consent can cause problems when you sell or insure the house.

In short

Write a clear scope, build a categorised budget with a separate contingency, sequence the trades carefully, confirm licences, insist on written contracts, and check your consent position early. None of it is glamorous, but it is what lets the tiles and tapware be the fun part.