How to Quote a Roofing Job in NZ — Measure Off the Details, Not the Plan Area
Updated: Jul 9
Roofing quotes in NZ fail two ways: priced off the plan-view area when the labour lives in the junctions, or priced at one fastener spec when the wind zone and corrosion zone set another. Here is the quoting sequence that holds up — measurement, spec, multipliers, exclusions.
By Steve Parker · Trueworks · NZ construction estimation · 5 min
What you'll learn in this post
What to measure beyond sheet area — and where the labour actually sits
The wind-zone and corrosion-zone spec lines that change the price
The exclusions that keep re-roof surprises off your account
Quick answer: A defensible NZ roofing quote starts with a takeoff measured off the MRM Code of Practice details, not the plan area: sheet m² by profile with pitch-corrected area, flashings by lineal metre and girth, penetrations counted individually, underlay, and fasteners by class. Two spec lines move the price before labour is touched: the NZS 3604 §5 wind zone (fastener density tightens from ~900 mm centres toward 450-600 mm at eaves in Very High and Extra High zones) and the AS/NZS 2312.1 corrosion zone (Class 3 fasteners inland, Class 4 within ~500 m of coast, Class 5 stainless in C5 marine under AS/NZS 3566). On re-roofs, the purlin condition is the exclusion that matters — H3.2 treated purlins void most metal-sheet warranties under MRM CoP §4.5. Wastage on long-run: 5-10% depending on cut-up; flashings 10%.
Step 1 — measure what the details show
The plan area is the start, not the measure. A roofing takeoff that prices accurately carries:
Sheet area, pitch-corrected — plan m² divided by the cosine of the pitch; an 8° roof adds ~1%, a 30° roof adds ~15%
Flashings by lineal metre AND girth — ridge, hip, barge, apron, valley, parapet capping; girth drives the folded material and the price per metre
Penetrations counted individually — each pipe boot, flue, skylight is detail labour, not area
Box gutters and internal gutters separately — MRM CoP §10 falls (minimum 1:100, design target steeper), overflow provision, and sump outlets are hours, not metres
Underlay, netting/safety mesh, and fixings as their own lines
The labour split tells the story: on a cut-up villa roof, junction and flashing labour routinely exceeds the sheet-laying labour. Quotes priced per-m² of plan area systematically under-price exactly those roofs.
Step 2 — the two spec lines that set the price
Wind zone (NZS 3604 §5). Fastener density and pattern tighten with the zone — Medium-zone spacing on an Extra High site fails the engineer's PS3 inspection and the manufacturer's warranty both. Name the zone on the quote and price the density it requires.
Corrosion zone (AS/NZS 2312.1 + AS/NZS 3566). Inland C2-C3 takes Class 3-4 fasteners; the C5 marine band (within ~100 m of surf coast) requires Class 5 stainless and a marine-rated coating system. Class 5 fasteners cost 3-6× Class 3. The coating warranty itself is zone-conditional — standard pre-painted product warranties exclude C5 unless the marine product is specified.
Both lines belong written on the quote: "Priced for [zone] per NZS 3604 §5 / AS/NZS 2312.1 [category]; fastener class [X] per AS/NZS 3566." If the architect's documents are silent, that line converts a later dispute into a variation.
Step 3 — re-roof multipliers and the purlin question
Re-roofs carry costs new roofs do not:
Strip and dispose — by m², with a separate line if asbestos-suspect material is possible (survey excluded, named)
Purlin condition — MRM CoP §4.5: treated timber (H3.2 LOSP and above) in direct contact with metal sheet voids most manufacturer warranties. Most pre-2000 roofs sit on H3.2 purlins. Price the purlin upgrade, or exclude it in writing — never silently absorb it
Pitch compliance — the new profile's minimum pitch (MRM CoP §4.12; commonly 3-8° depending on profile) against the existing structure. A 2° existing pitch cannot take most trapezoidal profiles and the fix is structural, not roofing
Access — edge protection, scaffold or harness regime, and two-storey handling time
Step 4 — wastage, validity, exclusions
Long-run wastage runs 5% on simple gables to 10% on cut-up hips and valleys; flashing offcuts ~10%. Steel-based sheet pricing moves — 30-60 day validity with a re-pricing line is standard practice.
The exclusions list that protects a roofing quote:
Purlin replacement or treatment-class upgrade (unless priced as its own line)
Structural repairs found at strip
Asbestos survey and removal
Non-standard junctions not detailed on the drawings
Consent-condition costs (heritage roofline approvals, council inspections beyond standard)
Engineer-instructed changes after the named drawing revision
FAQ — quoting roofing jobs in NZ
Q1: Should I quote per square metre? Use per-m² rates internally for the sheet area only. The quote itself should price the measured takeoff — sheets, flashings by metre, penetrations by count — or the cut-up roofs will lose on every junction.
Q2: What wastage factor for long-run roofing? 5% on simple gable runs, 8-10% on hipped and cut-up roofs, plus ~10% on flashing stock. State the factor in your own records; the quote carries the resulting quantities.
Q3: Who is responsible if the purlins turn out to be H3.2? Whoever the quote says. Silent quotes inherit the problem — the warranty will not issue over treated purlins (MRM CoP §4.5), so the upgrade happens, and an unwritten scope lands on the roofer. One exclusion line moves it to the owner or head contractor as a variation.
Q4: Do I need different fasteners near the coast? Yes — AS/NZS 3566 Class 4 within roughly 500 m of the coast, Class 5 stainless in the C5 band near surf coastlines. Installing the inland class in a marine zone fails visibly inside 2-5 years and voids the sheet warranty with it.
Q5: What validity period should a roofing quote carry? 30-60 days is common while coil pricing is moving. Pair it with a stated re-pricing mechanism rather than silently honouring stale rates.
Get your next roofing tender measured properly
Drawings + the tender documents + 5 business days = a measured takeoff with pitch-corrected areas, flashing schedules, the zone-spec lines, and your exclusions drafted.
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About Trueworks
Trueworks is built by Steve Parker — 20 years on the analytical side of NZ construction. Variation reviews, contract advisory, programme review, and AI-augmented document workflows. Trueworks is the productisation of that practice for builders: same defensible analysis, at a price and pace a NZ builder can actually use.
Every report is checked and signed off by me personally before it goes out. If you have a roofing tender closing, the easiest way to find out if Trueworks is useful is to send the drawings.
hello@trueworks.co.nz · trueworks.co.nz
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