Apply the answer
Keep hidden work separate from the known reroof scope.
Use Quote Checker to see whether timber/structural repairs and other opening-up items are included, excluded or still unknown.
How the quote should deal with unknown work
The written scope should say what timber/substrate repair is already included, what is excluded or provisional, who can authorise additional work and how a variation is priced. Consumer building-contract rules also matter for qualifying residential building work. Sources: Building Performance; Building Performance.
| Weak wording | Better question to ask |
|---|---|
| “Timber repairs extra if required.” | What timber repair is included, what triggers a variation, how will quantity/rate be recorded and who approves it before work proceeds? Sources: Building Performance. |
| “Underlay included.” | Which underlay/system is included, and what happens if the substrate/support beneath it needs repair? Sources: Roofing Association of New Zealand. |
| “Make good as required.” | Which components are covered by “make good”, and which are an allowance or excluded? Sources: Consumer Protection. |
Document what is found before it disappears again
For significant unexpected work, photographs and a short written variation record can make the final invoice, warranty history and future maintenance easier to understand. This is especially useful because the repaired timber/substrate may be hidden again once the new roof is installed. Sources: Building Performance.
Use Quote Checker to keep unknown scope visible
Related questions
Can a roofer know exactly how much rotten timber is under the old roof before stripping it?
Sometimes some defects are visible or inferable beforehand, but concealed battens/purlins/substrate can remain uncertain until opening-up. The quote should explain how that uncertainty is handled. Sources: Roofing Association of New Zealand.
Does RoofHub add a standard timber allowance to every reroof?
No. A project-specific contractor case can demonstrate the risk of hidden work, but it is not a defensible universal quantity or price allowance for another roof.
Sources and review notes
Prepared by RoofHub editorial team. Reviewed . A source check confirms what a page states, not an independent inspection or invoice audit. Published project accounts are attributed to their publishers.
- primaryRoofing Association of New Zealand: RANZ Re-Roofing Guide - RANZ describes this as an annually updated NZ consumer guide to reroofing materials, systems, terminology, scope and workmanship. Used for project-planning context rather than contractor ranking. Page checked 2026-10-21. Publication date not stated. · industry-technical
- primaryBuilding Performance: Contracts for your building project (2026-01-15) - Building Performance guidance last updated 15 January 2026. Residential building work costing $30,000 or more including GST requires a written contract; disclosure and checklist requirements also apply at that threshold or when requested. Page checked 2026-10-21. Publication date shown above. · government
- primaryBuilding Performance: Implied contract terms - MBIE guidance on default residential building contract terms, including payments, variations, consents, subcontractors and disputes where a contract is missing required provisions. Page checked 2026-10-21. Publication date not stated. · government
- marketTopline Roofing: Mt Eden bungalow reroof - hidden timber failure - Project-specific reroof account for an approximately 160 m² bungalow where significant purlin deterioration became visible after strip-off and about 35 linear metres of purlins were reported replaced. Publisher-reported project. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date not stated. · practitioner observation
- marketEdwards & Hardy: RANZ Re-Roofing Guide 2025: What NZ homeowners need to know (2026-01-12) - Long-established NZ roofing/maintenance business summarising practical reroof issues including concealed timber, underlay, flashing and moisture problems exposed after removal. The underlying RANZ guide remains the stronger industry authority; this source contributes practitioner framing. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date shown above. · practitioner observation
- marketHDK Long Run Roofing: Long run reroof in Kumeu - Project-specific reroof account involving three roof sections of different ages and timber deterioration discovered during removal. Useful for opening-up uncertainty; publisher-reported and commercially interested. Commercial interest: sells roofing services. Page checked 2026-10-21. Publication date not stated. · practitioner observation
- primaryConsumer Protection: Quotes and estimates - NZ government consumer guidance reviewed 21 October 2026. Distinguishes quotes from estimates, says accepted fixed quotes can only change where a variation is agreed, and states there is no legal requirement to pay a deposit; if one is requested, its consumer guidance says not to pay more than 10% of total cost. Page checked 2026-10-21. Publication date not stated. · government
Original calculations are labelled as examples. Historical prices stay dated, missing fields stay unknown, and conflicting specifications are flagged. Sources are not endorsements or paid rankings. Read our methodology or report a correction.
Keep exploring
Next step
Estimate it, refine it, or ask RoofHub.
Start with approximate information, use actual measurements when you have them, or ask RoofHub to explain the decision. A roofing contractor still needs to confirm the site, specification and final quotation.