Solar on corrugated iron roofs in Perth: what to know

Yes, you can install solar on a corrugated iron roof in Perth, and it's common on older character homes across Subiaco, Fremantle, North Perth, Leederville, Victoria Park, and Mount Lawley. What matters isn't the material itself, it's the condition and remaining life of the roofing underneath. Solar racking means roof penetrations, and putting those into iron that's close to end of life just sets you up to remove the panels, replace the roof, then reinstall the panels. Get the condition check right first and the rest is a standard installation.

This guide covers how to tell whether your iron sheeting is ready for solar, how mounting actually works on corrugated profiles, what the honest weight and structural picture looks like, and how to decide between installing now and re-roofing first.

---

What's the difference between corrugated iron and Colorbond?

Corrugated iron (also called CGI, corrugated galvanised iron) is the older, typically bare galvanised or painted steel sheeting installed on Perth homes before Colorbond became the standard, broadly pre-1990s.

Colorbond is BlueScope's coated steel product with a factory pre-painted finish. It carries a warranty of up to 36 years against perforation, though the actual term varies by environmental category (inland, coastal, or severe marine), the specific Colorbond range, and your location, so it's not a flat number for every property.

Zincalume sits in between: an aluminium-zinc alloy coated steel that looks similar to traditional galvanised iron but holds up better over time. More on that below.

The distinction that matters for solar: older corrugated iron is often approaching end of life, and installing racking on roofing that needs replacing within the next few years creates an avoidable cost. The panels come off, the roof gets replaced, and the panels go back on, a job you'd rather do once.

---

Is your corrugated iron roof actually ready for solar?

A condition assessment is the first step, before you get a solar quote.

Signs your iron sheeting is near end of life:

• Visible surface rust: orange staining or pitting on the steel
• Holes or perforations in the sheeting
• Previous patch repairs, which point to a past leak history
• Sheets that flex or "oil-can" under light foot pressure, a sign the structural integrity is going
• Chalky, flaking paint on painted corrugated iron

Signs your iron sheeting is still serviceable:

• Intact galvanised or Zincalume surface: silver-grey, no rust staining
• No visible holes or patches
• Paint still adhering, on painted iron
• Stiff underfoot, retaining its structural integrity

A roofer's inspection costs $200 to $400 in Perth and gets you an estimated remaining life for the sheeting. Anything under 10 years remaining is a strong argument to replace before solar goes on.

---

How does solar actually mount to a corrugated iron roof?

Two standard approaches, both built around the corrugation profile:

1. Top-fix brackets. The bracket attaches over the corrugation ridges and fixes down to the purlin or batten below via a self-drilling screw or lag bolt. The bracket foot sits on the ridge; the penetration goes through the valley, the lowest point of the sheeting, with appropriate sealing.
2. Lap-screwing into purlins. Direct screwing through the corrugation crest into the structural purlin below. This needs accurate purlin location, not always straightforward on older homes with non-standard framing, plus sealing with EPDM or neoprene washered screws to keep water out.

Every penetration through corrugated iron needs proper sealing. Perth's UV and heat conditions degrade sealant over time, so a quality product (neutral-cure silicone, or manufacturer-specified EPDM washered screws) is essential. Cheap sealing fails, and when it does, it fails at the roof penetration, exactly where you don't want a leak. For a closer look at what good sealing and flashing looks like across roof types, see our guide to solar roof penetrations and flashing in Perth.

---

Does the extra weight matter for an older roof?

Solar adds real weight to a roof, and it's worth being accurate about how much.

A standard framed panel in the wattage class installers use today weighs roughly 20 to 25kg. A 10kW system runs around 22 to 23 panels at current panel wattages, which puts the added load at roughly 440 to 575kg spread across the roof area.

Standard 1980s and newer Australian residential framing is generally built to carry loads like this, but the margin is tighter than a lower weight estimate would suggest. Older corrugated iron homes (pre-1960) may have non-standard rafter spacing and lighter purlin or batten sizing than modern construction. Get a structural engineer to check the roof framing if:

• The building appears to have non-standard construction
• The iron sheeting shows noticeable sag between purlins, a sign of structural deflection
• The original plans point to light-gauge framing

If there's any doubt at all about the roof's age or condition, that engineer check is worth the cost before solar goes on, not after.

---

Should you replace the roof before or after solar?

For Perth character home owners with corrugated iron, the decision comes down to remaining roof life.

15+ years remaining: Solar on the existing roofing is reasonable. Use quality mounting with proper sealing, and plan for the panels to come off temporarily whenever the roof eventually gets replaced.

5 to 15 years remaining: Weigh the cost of replacing now against replacing later.

• Replace the iron with Zincalume corrugated (keeps the character home look, longer lifespan) and install solar as one combined project, or
• Install solar now and accept a remove-and-reinstall cost of roughly $1,500 to $3,000 in 5 to 10 years' time.

Under 5 years remaining: Replace the roof first. Installing solar on iron that's already near end of life just locks in an immediate remove-and-reinstall cycle that wastes the installation cost.

Heritage precincts: Some Perth character homes in heritage areas have restrictions on roof replacement materials. Heritage Council or local council planning approval may be required to swap iron for an alternative roofing product, and the replacement may need to match the original. Check heritage constraints before committing to a roof replacement plus solar project. For a broader comparison across Perth roof materials, see our guide to solar on different roof types in Perth, and if your roof is closer to a straightforward re-roof decision, roof age and solar panels in Perth walks through the timing in more detail.

---

What about Zincalume: is it the right upgrade?

Zincalume, BlueScope's aluminium-zinc alloy coated steel, looks similar to traditional galvanised iron but holds up noticeably better: a typical service life in the range of 30 to 40 years. If you're replacing worn corrugated iron and want to keep the character home aesthetic, Zincalume is the modern equivalent. Solar mounts to it the same way as standard corrugated iron.

One caution: standard galvanised fasteners and some aluminium racking components can cause galvanic corrosion where they contact Zincalume in coastal environments. In Perth suburbs within about a kilometre of the ocean (Fremantle, Cottesloe, North Beach, Trigg), specify stainless steel or otherwise compatible fasteners for all mounting hardware. If you're weighing Colorbond instead of Zincalume for the re-roof, our Colorbond roof solar guide covers installation on that surface specifically.

---

Does corrugated iron roofing affect your home insurance?

Some Perth insurers apply specific conditions to older corrugated iron roofing, including age-related exclusions for storm damage claims and a requirement to report the roofing material and its condition.

Review your building insurance policy before proceeding with solar, and let your insurer know about the intended work. This matters most for character homes in Fremantle and inner-suburban Perth, where insurers are more used to dealing with older roofing materials.

---

Corrugated iron roofing on older Perth homes is a workable surface for solar, provided the iron is in serviceable condition with at least 10 years of life left in it. Get a professional roofing assessment before you commit, insist on quality sealing at every penetration point, and go in with a clear plan for what happens when the roof eventually needs replacing. Character home owners in heritage precincts should also confirm any planning restrictions on roof replacement materials before locking in a project.