Roof Flashing Types Explained for Metal, Tile and Polycarbonate Roofs

One of the most common ordering mistakes we see is treating all roof flashing as the same product. The roof flashing types you need for a Colorbond corrugated roof are completely different from the ones that work on a tiled roof, and different again from what suits a polycarbonate patio. The material, the profile and even the way you fix it all change depending on the substrate underneath. 

This guide breaks down the main roof flashing categories by the roof type they suit, so you can order the right product the first time and keep your roof watertight for years. We will also cover the install rules that apply across the board and how to colour-match your flashings to your existing roof. 

Why Flashing Depends on the Roof Substrate 

Flashing is the shaped metal (or flexible membrane) that seals the vulnerable junctions on a roof – where the roof meets a wall, a chimney, a valley, a ridge or a penetration like a flue pipe. Every roof has them, and every one is a potential leak point if the flashing is wrong. 

The reason substrate matters is simple: 

• Metal roofs (Colorbond, Zincalume) use rigid steel flashings that are profile-matched to the roofing sheet. They are fixed with screws and sealed with compatible sealants. 
• Tiled roofs (concrete, terracotta) use a mix of lead sheet, Smartform peel-and-stick, and steel flashings dressed over or under the tiles. The irregular tile surface needs a flexible material that can mould to the profile. 
• Polycarbonate roofs (Laserlite, Suntuf, multiwall) expand and contract significantly with temperature. Rigid metal flashing clamped tight against polycarbonate will eventually crack the sheet. These roofs need flexible boots, foam closure strips and self-adhesive flashings. 

Get the substrate wrong and you either end up with leaks, cracked sheets, or a warranty claim that gets rejected. Browse our full roof flashing range to see the options grouped by roof type. 

Flashings for Metal Roofing 

If your roof is Colorbond corrugated roofing, Trimdek or Metlok 700, you need steel flashings that match your sheet profile. We manufacture all of these in-house at our Truganina facility, cut and folded to your specifications in any Colorbond colour, with lengths up to 8 metres. Here are the main types: 

• Apron flashing – the L-shaped strip that seals the junction where a roof meets a vertical wall (chimney side, dormer, gable wall). Available profiled to suit corrugated, Trimdek and Klip-Lok sheets. 
• Barge capping – covers the exposed edge of the roof at the gable end, protecting the fascia and barge board from water ingress. Our most popular metal roof flashing product. 
• Ridge flashing (flat ridge) – sits over the peak where two roof planes meet. Shaped to match the corrugation profile for a tight fit. 
• Valley gutter flashing – channels water at internal roof intersections where two planes meet in a V. Made from 0.55 BMT steel for strength. 
• Box gutter – a concealed rectangular channel between parallel roof planes or against a parapet wall. We stock 200 x 200 x 200 mm in both Colorbond and Zincalume, plus custom sizes. 

Browse the full metal roof flashing range for profile-specific options. 

Minimum Pitches and AS/NZS 1562.1 Overlaps 

AS/NZS 1562.1 governs metal roof cladding in Australia, and it sets rules for flashing overlaps and minimum pitches that affect how your flashings perform. The key numbers: 

• Flashing side laps on metal roofs should overlap by at least 150 mm. 
• End laps (where one length of flashing meets the next along its run) need a minimum 150 mm overlap, sealed and mechanically fastened. 
• At roof pitches below 5 degrees, overlap requirements increase and sealant becomes critical. Always check the manufacturer’s installation guide for your specific profile. 

If you are working on a low-pitch metal roof, our roof sarking guide covers the condensation management rules that often come into play alongside flashing on these builds. 

Flashings for Tiled Roofs 

Tiled roofs present a different challenge. The irregular, overlapping surface of concrete or terracotta tiles means you cannot simply fold a flat piece of steel and expect it to seal. Tile flashings need to flex, dress and mould around the tile profile. 

• Lead sheet – the traditional choice for tile roof flashing. Soft, malleable and extremely durable. Dress it over tile profiles at chimneys, wall abutments and complex junctions. We stock 600 x 600 mm sheets in Code 3 (1.32 mm, flexible for soakers and detailing) and Code 4 (1.80 mm, robust for valleys and parapets). Manufactured to AS 1804. 
• Smartform fast flashing – a lead-free, peel-and-stick aluminium alternative. Cuts with scissors, installs up to 50% faster than lead, and moulds to corrugations, ridges and curved surfaces. Ideal for DIYers and trade alike. 
• Colorbond tile flashings – for simpler tile junctions like barge trims and gable ends, standard steel flashings work when the tile course allows them to sit flat. Browse our tile roof flashing range for the full selection. 

For tile roofs in particular, flashing failure is one of the most common causes of water ingress in older Melbourne homes. If you are replacing weathered lead on a heritage property, keep the same Code and overlap dimensions. 

Flashings for Polycarbonate and Laserlite Roofs 

This is where people make the most mistakes. Polycarbonate sheets like Laserlite 2000 and Laserlite 3000 are lightweight, UV-resistant and brilliant for patios, carports and pergolas. But they expand and contract far more than metal or tile with temperature swings. 

That means you cannot clamp rigid steel flashing tightly against them. The sheet will crack at the fixing point within a season or two. 

What to use instead: 

• Dektite boot flashing – an EPDM rubber cone on a pliable aluminium base. Designed to seal pipe and flue penetrations through metal, polycarbonate or glass roofs. Trims to fit any pipe diameter from 5 mm to 127 mm. No mastics, no hot works. 
• Smartform peel-and-stick – works on polycarbonate junctions where you need a flexible, self-sealing strip rather than a rigid folded flashing. Moulds to corrugated and Greca profiles. 
• Foam closure strips and infill strips – seal the gap between the polycarbonate sheet and the purlin or rafter at the eaves and ridge. Essential for keeping out rain-driven water, insects and debris. Available in our polycarbonate accessories section. 

Always use the screws recommended by the polycarbonate manufacturer. Over-tightening standard roofing screws will stress the sheet. We stock one-shot polycarbonate fixing screws with expansion-friendly washers for exactly this reason. 

For a full overview of our polycarbonate range, visit the polycarbonate roofing page. 

Flashings for Skylights and Penetrations 

Skylights, flue pipes, vent stacks and solar conduits all punch through the roof surface, and every one needs a watertight seal regardless of the roof type. 

• Skylight flashing kits – we carry Velux and Keylite flashing kits matched to specific skylight models and roof types (shingle, tile, metal). The correct kit is essential for the manufacturer’s 10-year no-leak warranty. 
• Dektite boot flashings – for round penetrations like flue pipes and vent stacks. Available in standard, high-pitch (35-65 degrees) and combo/retrofit models. 
• Custom flashings – for non-standard penetrations, we manufacture bespoke flashings to your measurements. Solar panel conduits, evaporative cooler ducts, antenna mounts – if it goes through the roof, we can flash it. 

Install Rules That Apply to All Roof Flashing Types 

Whatever the substrate and whatever the flashing type, these rules hold across the board: 

• 150 mm minimum overlap – where one length of flashing meets the next, overlap by at least 150 mm and seal the joint inside. 
• Screws over rivets – use screws with neoprene washers rather than rivets for primary flashing fixings. Screws create a stronger, more watertight connection and are easier to remove if you ever need to replace a section. 
• Expansion joints on long runs – metal expands in the sun. On flashing runs longer than 12 metres, allow for thermal movement with an expansion joint or a sliding lap. 
• Compatible sealant – always use a sealant compatible with Colorbond or Zincalume steel. Acidic-cure silicones can corrode the coating. 
• Uphill side laps over – the uphill (higher) flashing always sits on top of the downhill piece, so water flows over the join, never into it. 

Matching Flashing Colour to Your Roof 

Nothing looks worse than a Surfmist roof with Woodland Grey flashings. At Singh Roofing Supplies, we manufacture every flashing in every standard Colorbond colour, including the Matt range. We keep raw COLORBOND, ZINCALUME and galvanised coil in stock at all times, so turnaround on custom flashings is typically 48 hours. 

If you are unsure which colour matches your existing roof, check our Colorbond colour chart guide, which covers all 22 current core colours.  

FAQ and Tips 

What types of roof flashing are used on metal roofs? 

Metal roofs use apron flashing at wall junctions, barge capping at gable ends, valley gutter at internal intersections, ridge flashing at the peak and box gutter between parallel planes. All available in Colorbond or Zincalume. 

Can I use standard metal flashing on a polycarbonate roof? 

No. Polycarbonate expands and contracts significantly with temperature changes. Rigid metal flashing clamped tight will eventually crack the sheet. Use flexible options like Dektite boots for penetrations and Smartform for junctions. 

How much should roof flashing overlap? 

At least 150 mm for metal-to-metal flashing joints. For lead flashing on tiles, a minimum 100 mm overlap, dressed and sealed. Always fasten mechanically with screws and seal with a compatible sealant. 

What is the best flashing for a chimney on a tiled roof? 

Lead sheet (Code 3 or Code 4 depending on the exposure) is the traditional and most durable option. For a faster, lead-free alternative, Smartform moulds to tile profiles and installs in half the time. 

Do skylight flashings need to be brand-specific? 

Yes. Velux and Keylite skylights each require model-matched flashing kits for the manufacturer’s no-leak warranty to apply. We stock the full range of EDL, EDW and ECL kits for both brands. 

Can Singh Roofing make custom flashings for unusual junctions? 

Absolutely. We manufacture custom flashings in any Colorbond or Zincalume colour, folded to your specifications, with lengths up to 8 metres. Turnaround is typically 48 hours. Call us on (03) 9394 1400 or email your drawings to orders@singhroofingsupplies.com.au. 

Need help choosing the right flashing for your project? Contact the team at Singh Roofing Supplies on (03) 9394 1400, or visit us at 2/1 Network Drive, Truganina VIC 3029. We deliver Australia-wide, with same-day or next-day delivery across Melbourne.