When is it time to re-roof?
Age on its own doesn't settle it. MBIE's Building Code guidance expects non-structural roof cladding to last at least 15 years with normal maintenance, and plenty of New Zealand roofs go well past that.
The signs that point to a re-roof are rust eaten right through the iron, tiles cracking across the whole roof, decramastic with most of its stone chips gone, and leaks that move after every repair. A sag along the roofline can mean tired purlins or rafters underneath. Still unsure? Our guide to restoring or re-roofing goes through the trade-offs.
Before anyone lifts a sheet, rule out asbestos
WorkSafe says a home built before 1 January 2000 may contain asbestos. RANZ, the roofing industry association, advises testing Super 6 sheets, old decramastic tiles, asphalt shingles and any bituminous membrane before a re-roof starts. Until there's a result, nobody should cut, drill or water-blast that roof. See asbestos roof removal if it tests positive.
How a re-roof usually runs
A proper look first
A good roofer checks the roofing, flashings, spouting and the timber underneath, from the ceiling space as well as outside. Ask for photos of what they find.
Scaffolding goes up
WorkSafe's example control for roofing on a house is scaffolding with full edge protection, and single-storey homes need the same fall protection as two-storey ones. It belongs in every quote.
Strip-off, a section at a time
Ask how they'll keep the house weathertight overnight. Rotten purlins or battens show up now, so the quote should say how extra timber work gets agreed.
Underlay, roofing and flashings
E2/AS1, the Building Code's acceptable solution for keeping water out, requires roof underlay under all profiled metal longrun and metal tile roofing. New flashings, and often new spouting (gutters), go on while the scaffold is up.
Sign-off
For consented work, each LBP gives you and the council a Record of Work, then you apply for the code compliance certificate. Any residential contractor must also hand over their insurance details, product warranties and the maintenance those warranties need.
Do you need a building consent?
Often not, but don't assume. Schedule 1 of the Building Act allows a comparable product to replace the old one in the same position without consent, and MBIE's exempt example is a 20-year-old profiled metal roof replaced with new profiled metal.
Going lighter in the same position is generally exempt as well. MBIE's example is an old clay tile roof replaced with longrun or pressed metal tiles, with the stronger wind uplift allowed for. Going heavier, such as corrugated iron to concrete tiles, needs consent because of the extra load on the framing.
Some councils are stricter: Wairoa's says a change of purlins or roofing system needs consent. And a roof that failed early by letting water in isn't exempt. MBIE leaves the call to the homeowner, so ask your council if you're unsure, or read our building consent guide.
Does the roofer need to be an LBP?
A re-roof that needs consent is restricted building work, so a Licensed Building Practitioner (LBP) has to do or supervise it. That can be a Roofing LBP, a registered plumber, or for lightweight profiled metal, a Carpentry LBP.
Exempt work doesn't legally need an LBP. RANZ still suggests asking who'll supervise on site, whether anything is subcontracted, and whether you'll get a Record of Work or a Roof Completion Report. Our guide to checking an LBP shows how.
What goes back on?
Longrun steel comes in corrugate, which Dimond calls a firm favourite with Kiwis, plus trapezoidal rib and tray profiles. Pressed metal tiles give a tiled look for much less weight: Gerard says its steel tiles weigh about a tenth of a concrete tile roof.
Near the coast or a geothermal area, the product matters as much as the look. RANZ says the major metal roofing makers offer a free material warranty check for your area, so ask your roofer to run it. Our longrun roofing page compares the options.
What makes a re-roof bigger or smaller?
Size and shape come first: a simple gable goes quicker than a hip roof with valleys, dormers and skylights, and two storeys mean more scaffolding. Then there's what's underneath. Rotten timber, a switch from tile battens to purlins, asbestos removal, a chimney coming out, new spouting and any consent all add work. Ask each roofer to break the quote into parts so you can compare like with like.
What a good re-roof quote spells out
- The legal business name, and the LBP number for restricted building work
- The roofing by brand, product and profile, such as COLORSTEEL MAXAM corrugate, not just 'coloured steel'
- Underlay, flashings, fixings, spouting and scaffolding, each listed
- Who applies for any consent, and who arranges asbestos testing
- How extra timber work gets agreed
- Payments that follow the work, with any deposit no more than the 10% Consumer Protection advises
- The workmanship warranty, and the maker's material warranty for your address
- For work of $30,000 or more including GST, a written contract plus the official disclosure information before you sign
Your jobs, and the roofer's
You can
- Photograph rust, lifted sheets or broken tiles from the ground
- After heavy rain, shine a torch into the ceiling space from the hatch
- Ask the council about character or heritage rules on your street
- Tell your insurer before work starts, since cover may not apply during renovations
Leave to a roofer
- Anything on the roof itself, wet or dry
- Asbestos testing and removal
- Checking the pitch suits the new profile
- Consent applications and the Record of Work
What we'd do before signing for a re-roof
We'd settle the asbestos question first. Then we'd get written quotes naming the same product and profile, so they can genuinely be compared, with the consent position in writing. We'd lean towards the roofer who explains the hidden parts, the underlay, flashings and timber, as carefully as the colour. When you're ready, tell us about the job and we'll pass it to one checked local roofer.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.