Why guarantees matter when hiring a quantity surveyor
A quantity surveyor’s job is to help you control costs, budget accurately, and reduce the risk of surprises on a build or renovation. Because they are working with pricing, forecasting, progress claims, variations, and sometimes procurement advice, a mistake can quickly turn into real money.
That is why it is worth asking not just what the quantity surveyor will do, but what they stand behind. In New Zealand, a good service agreement should spell out:
- the scope of the quantity surveyor’s services - what parts of their work are guaranteed or warranted - what limits apply to their responsibility - how errors will be corrected - what insurance they carry - how disputes will be handled
A quantity surveyor is not the same as a builder, plumber, electrician, or engineer, so you should not expect the same type of workmanship warranty you would get from a tradesperson completing physical work on site. But you should still expect professional care, accurate documentation, and clear accountability.
What a quantity surveyor should guarantee
A quantity surveyor generally provides professional services rather than a physical product. So their “guarantee” is usually about the quality and reliability of their advice, estimates, reports, and calculations.
In a New Zealand context, a sensible service agreement should guarantee that the quantity surveyor will:
- perform the work with reasonable skill and care - prepare estimates and measurements using recognised industry methods - base figures on the information available at the time - disclose assumptions, exclusions, and risks clearly - notify you promptly if new information changes the cost outlook - keep records that can be checked later
If the quantity surveyor is offering a “fixed price” service, make sure that means the fee for their services, not a guarantee that the final building cost will never change. Build costs in NZ can move due to labour shortages, weather delays, material lead times, and seasonal demand.
Workmanship guarantees versus professional service warranties
The phrase “workmanship guarantee” is often used loosely in home improvement, but for a quantity surveyor it needs careful wording.
A quantity surveyor normally does not have “workmanship” in the same sense as a carpenter or tiler. Instead, the relevant promise is a professional service warranty. This should cover whether their work was prepared competently and accurately.
Here is the practical difference:
| Type of promise | Applies to | What it usually covers | |---|---|---| | Workmanship guarantee | Physical trades work, such as building, plumbing, tiling, painting | Defects in the installation or finish | | Product warranty | Materials, fixtures, appliances, software | Faults in the product itself under the supplier’s terms | | Professional service warranty | Quantity surveying, design, accounting, consulting | Errors in calculations, advice, reports, or procurement support |
For a quantity surveyor, a useful warranty might say they will correct genuine errors in measurements, cost plans, or progress claims at no extra charge if the mistake was theirs and the job is within the original brief.
Product warranties: what the quantity surveyor is and is not responsible for
A quantity surveyor may recommend products, compare specifications, or help you track allowances for fixtures and finishes. But they do not normally give the product warranty themselves.
The warranty usually comes from:
- the manufacturer - the importer - the supplier or retailer - the installer, if the item was fitted as part of their trade work
In New Zealand, this matters because a defective tap, heat pump, waterproofing membrane, or cabinetry hinge may involve more than one party. For example:
- a supplier may cover the faulty product - a plumber, electrician, or builder may cover the installation - the quantity surveyor may only be responsible if they incorrectly specified, costed, or documented the item
Ask the quantity surveyor to identify clearly who is responsible for what. That helps avoid finger-pointing later.
The Consumer Guarantees Act and quantity surveying services
For most homeowners, the Consumer Guarantees Act 1993 (CGA) is an important protection when hiring a quantity surveyor for personal, domestic, or household use.
Under the CGA, services supplied to consumers must, among other things:
- be carried out with reasonable care and skill - be fit for the purpose you told the supplier about - be completed within a reasonable time, if no timeframe was agreed - be provided for a reasonable price, if no price was set
If a quantity surveyor gives you a cost estimate or prepares a variation assessment that is careless or significantly wrong, the CGA may be relevant. The remedy will depend on the seriousness of the issue and whether the mistake can be fixed.
Important note: the CGA applies to consumer work, but some business-to-business contracts can exclude it. If you are hiring the quantity surveyor as part of a trust, company, or development venture, do not assume consumer protections will automatically apply.
What to check in the contract before you sign
A clear written agreement is the best protection. Before you engage a quantity surveyor, ask for the following to be set out in writing:
- the exact scope of work - whether the service includes feasibility estimates, detailed cost plans, tender analysis, progress claim reviews, or variation advice - what documents the quantity surveyor will rely on - what assumptions have been made about labour, materials, timelines, and site conditions - whether GST is included in quoted figures - how revisions and extra site visits are charged - who owns the reports and whether you can share them with your builder, architect, lender, or council - the timeframe for responding to queries - the complaint process if you are unhappy
Also ask whether the quantity surveyor is a member of a recognised professional body and whether they hold professional indemnity insurance. Membership is not a legal requirement in every case, but it can provide extra confidence.
What warranties and protections you should ask for specifically
A good quantity surveyor may not offer a long list of “guarantees”, but they should be willing to stand behind their professional work. Ask for these practical protections:
- **Error correction**: If there is a genuine arithmetic or transcription error, will they fix it quickly at no charge? - **Scope correction**: If they misunderstood part of the brief, will they amend the report? - **Reasonable skill and care**: Will they confirm they are undertaking the work competently and in line with accepted quantity surveying practice? - **Insurance coverage**: Do they carry professional indemnity insurance, and what does it cover? - **Timeframes**: Will they meet agreed deadlines for budgets, tender assessments, or payment certificates? - **Clarification duty**: Will they flag assumptions, exclusions, and uncertainties before you rely on the numbers?
It is also fair to ask how they handle price changes. In New Zealand, material costs can change quickly, especially for imported items, seasonal labour pressure, or supply chain delays. A good quantity surveyor should not promise certainty they cannot honestly provide.
What recourse a homeowner has if the work is faulty
If you believe the quantity surveyor has made a faulty estimate, bad calculation, or careless recommendation, act quickly and keep everything in writing.
Start with these steps:
1. **Review the contract and scope** Check exactly what they were engaged to do. Some disputes arise because the client expected a full build budget when only a high-level estimate was commissioned.
2. **Gather the evidence** Keep emails, reports, marked-up plans, invoices, and any documents showing where the error appears.
3. **Notify the quantity surveyor promptly** State the issue clearly and ask for a written response. In many cases, a professional will correct genuine mistakes once they are shown.
4. **Request a remedy** Depending on the problem, you may ask for: - a corrected report or estimate - a fee reduction - reimbursement for direct losses caused by the mistake - another professional review
5. **Escalate if needed** If the matter cannot be resolved, consider mediation or a formal complaint through the firm’s dispute process. If the work falls under the CGA or a contract claim, you may also seek legal advice about your options.
If the issue affects a building project, other rules may also apply
Sometimes a quantity surveyor’s work is connected to actual building faults, not just cost errors. In that case, other legal and regulatory systems may come into play.
For example:
- **Building work** may require consent from your local council, depending on the work. - **Plumbing, gasfitting, and drainlaying** are restricted work and are regulated by the Plumbers, Gasfitters and Drainlayers Board (PGDB). - **Electrical work** is regulated by the Electrical Workers Registration Board (EWRB).
A quantity surveyor is not usually responsible for carrying out or certifying this restricted work, but they should understand how it affects scope, cost, and timing. If they are budgeting for a renovation that includes a new bathroom, kitchen, heat pump, or wiring changes, their figures should reflect the compliance costs that often come with NZ projects.
If the faulty outcome is actually caused by another trade, the recourse may need to be directed at that trade, not the quantity surveyor.
Red flags to watch for
Be cautious if a quantity surveyor:
- refuses to give you a written scope - promises exact final costs for an early-stage project without qualification - will not explain assumptions or exclusions - has no clear process for correcting mistakes - cannot show relevant experience in residential work - is vague about insurance or qualifications - discourages you from comparing quotes
A very low fee can be tempting, but in a tight NZ building market, a cheap estimate that misses key items can cost much more later. Get at least two or three written quotes and compare not only price, but also scope, exclusions, and deliverables.
Practical checklist before you hire
Use this checklist before signing anything:
- Ask for a written proposal and service agreement. - Confirm exactly what the fee includes and excludes. - Check whether GST is included. - Ask about professional indemnity insurance. - Ask how errors are corrected. - Confirm the expected turnaround time. - Make sure the brief matches your project type: renovation, new build, extension, or insurance claim. - Keep every estimate and variation in writing.
The bottom line
A quantity surveyor in New Zealand should not be selling unrealistic certainty. What they should offer is clear scope, professional care, transparent assumptions, and a willingness to correct genuine mistakes.
For homeowners, the strongest protection is a good written contract backed by the Consumer Guarantees Act where it applies. Combine that with multiple quotes, checked credentials, and clear communication, and you will be much better placed to avoid cost blowouts and resolve problems if something does go wrong.