Colorbond roof replacement

Replacing a roof with Colorbond steel means stripping the old tiles or sheets, repairing or replacing battens, laying sarking and fixing new pre-painted steel sheets with new flashings, ridge capping and usually new gutters. It suits roofs where the tiles have become brittle, the battens are failing, or the owner wants a lighter roof. In Hume, changing from tiles to steel needs a building permit, and the metal roofing must be installed by a plumber licensed or registered for roofing work. The roof plumber or builder you are put in touch with here is an independent business that quotes, takes the permit responsibilities and does the job.

When does replacement make more sense than restoration?

• Tiles crack when walked on, or many are already broken.
• Battens are sagging, rotten or poorly fixed, which shows as a wavy roof line.
• An old metal roof has rust holes through the sheets, not just surface rust.
• The roof is asbestos cement and you want it gone rather than managed.
• You are adding solar, a skylight or an extension and want a lighter, simpler roof.
• Repeated repairs keep failing and a restoration would only buy a few years.

Options compared

Option	Best for	Main trade-offs	Melbourne price guide
Restore existing tiles	Sound tiles and battens	Cheapest path, but the roof stays heavy and tiles keep ageing	$4,200 to $11,550
Re-roof in Colorbond steel	Failing tiles or worn metal	Needs a permit when changing material in Hume; higher upfront cost	$84 to $190 per sqm
Full replacement, single-storey home	Whole-roof jobs priced as a package	Price depends on removal, battens, gutters and access	$14,700 to $31,500
Asbestos cement removal before re-roof	Fibro or asbestos cement roofs	Licensed removalist, disposal at an authorised site	$52 to $135 per sqm

The ranges are published Melbourne figures including GST from the What’s The Damage roofing table, checked October 2026. The asbestos removal figure covers removal only, not the new roof. The cost guide for roof work in Sunbury breaks down what sits inside each figure.

Do you need a building permit?

Hume City Council’s building permit guidance says a permit is required when changing the material of a roof, such as replacing a tiled roof with zinc or Colorbond. Replacing tiles with new tiles like for like does not need one. The same page says a plumbing certificate of compliance is required when the roofing plumber’s work is worth more than the value it states. Council asks owners to confirm permit requirements against the Building Regulations 2018 before work starts, so ask the provider who will apply for the permit and include that cost in the quote.

If your property is in Macedon Ranges and inside the Bushfire Management Overlay, the shire’s overlay page says modifications to existing homes need to include measures that improve bushfire resilience. Your building surveyor will tell you whether AS 3959 construction requirements apply to the new roof.

Which licences and protections apply?

Plumbing. The Building and Plumbing Commission says roofing (stormwater) work includes installing, replacing and repairing metal roofing, flashings, gutters and downpipes, under the Plumbing Regulations 2018. A licensed plumber in that class must issue a compliance certificate for work above the BPC’s value threshold, and only a licensed plumber can issue one. The BPC lists the NCC and relevant Australian Standards among the requirements for this class. For gutters and downpipes the key one is AS/NZS 3500.3 on stormwater drainage, and the BPC’s summary of the 2025 edition says plumbing work started on or after 20 October 2025 must follow that edition, which updated the rules for eaves gutter overflow and valley gutters. Ask how the new gutters will handle overflow.

Building. The BPC says to engage a registered builder for domestic building work worth more than the amount it publishes, counting labour, materials and GST. Check the builder’s registration on the BPC’s practitioner search before signing.

Home Warranty. From 1 July 2026, the BPC’s Home Warranty scheme applies to eligible domestic building work valued above its threshold under eligible contracts signed on or after that date. Contracts signed earlier with a Domestic Building Insurance certificate stay under that policy. Ask the builder which applies to your contract before you pay a deposit.

What a provider will check or need

• Roof area and pitch, measured on site or from plans.
• The existing material, and whether asbestos testing is needed.
• Batten and truss condition once a few tiles are lifted.
• Gutter, fascia and downpipe condition, and where the stormwater connects.
• Solar panels, aerials, skylights and flues that must be removed and refitted.
• Colour choice, insulation or sarking upgrades, and any heritage or bushfire controls.

What the work involves

1. Permit, if changing material, and an agreed start date with weather contingency.
2. Scaffold or edge protection around the house.
3. Strip tiles or old sheeting in sections and dispose of them.
4. Replace or re-space battens to suit steel sheeting, and lay sarking.
5. Fix new Colorbond sheets with the correct fasteners, then fit flashings, ridge and hip capping.
6. Replace gutters and downpipes if quoted, connect to the stormwater system, and test.
7. Refit solar and penetrations, clean up, and hand over the compliance certificate.

Asbestos roofs

If the existing roof may be asbestos cement, the Victorian Asbestos Hub says to use a licensed asbestos removalist, since builders and plumbers generally are not licensed to remove it, and that the waste must go to a site authorised to receive it. WorkSafe Victoria keeps a directory of licensed removalists on its asbestos page.

What a careful roof plumber will not do

• Start a change of material without a building permit in place.
• Lay steel sheets over old tiles or rotten battens.
• Leave you without a compliance certificate for the plumbing work.
• Strip an asbestos roof themselves without a removal licence.

Re-roofing around Sunbury

Tile roofs on Sunbury houses from the 1980s and 1990s are reaching the age where brittle tiles or tired battens make replacement worth pricing. On rural lots around Bulla and Diggers Rest, a shed or garage roof can be quoted at the same visit; the BPC has a restricted roofing class limited to Class 10a buildings such as garages, carports and sheds. The Sunbury suburb page explains which council rules apply where.

What to do next

Gather the house age, roof material, rough roof size and any photos, then request a re-roofing quote. If you are unsure whether replacement is needed, ask for a roof restoration price at the same inspection so you can compare both paths.

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