VELUX Custom Flashing for Metal & Low-Pitch Roofs: What You Need to Know Before You Buy
The VELUX skylight is only one part of a reliable roof installation. The flashing has to match the skylight size, roof profile and roof pitch so rainwater can be managed around the opening correctly.
For a tiled roof, the answer may be a standard VELUX flashing kit. For Corrugated, TrimDeck, Klip-Lok or a low-pitch metal roof, the right answer can be very different.
- Tile or conventional corrugated iron: VELUX EDW may be the correct standard flashing for compatible pitched-roof skylights.
- TrimDeck or Klip-Lok: VELUX states EDW is not suitable for these profiles; a suitable custom flashing solution is required.
- FS / VS / VSE / VSS on a low-pitch metal roof: Central Skylights offers 0–15° inclined custom flashing configurations for selected Corrugated, TrimDeck and Klip-Lok applications. The project must still be checked so the skylight is installed at a suitable angle.
- FCM / VCM / VCS: these flat-roof VELUX families use custom-made flashing matched to the skylight and roof.
Why flashing selection matters as much as the skylight model
A flashing system is the interface between the skylight and the roof. Its job is to collect and divert water around the opening and back onto the roof drainage path. It is not simply decorative metal trim.
Match the VELUX size
A C04 flashing is sized for a C04 skylight; an M08 flashing is sized for M08. Flat-roof models use their own four-digit size codes such as 2246 or 3046.
Match the roof profile
Rounded corrugated ribs, trapezoidal TrimDeck ribs and concealed-fix Klip-Lok sheets do not present the same surface around a roof penetration.
Match the pitch
The same metal roof profile can need a different flashing configuration on a low-pitch extension than it would on a conventional pitched roof.
Corrugated, TrimDeck and Klip-Lok are not interchangeable
Metal roofs can look similar from the ground, but their rib shape, rib height, fixing method and typical pitch range can be very different. That geometry changes how a skylight penetration needs to be detailed.
Corrugated
Conventional corrugated iron is a low-profile, rounded-rib roof. VELUX specifically lists EDW for tile and corrugated iron, subject to the product and installation requirements.
A custom Colorbond flashing can also be selected where the project calls for a fabricated solution.
TrimDeck
TrimDeck uses a wider pan and trapezoidal rib. VELUX specifically excludes Trimdek from its EDW flashing suitability, so this is a key custom-flashing application.
Central Skylights offers separate 0–15° and 15°+ TrimDeck options across many pitched-roof VELUX sizes.
Klip-Lok
Klip-Lok is a concealed-fix profile commonly used where low roof pitches are required. VELUX also specifically excludes Klip-Lok from EDW suitability.
Custom flashing needs to respect the roof profile, water path and skylight installation angle.Technical context: LYSAGHT lists CUSTOM ORB corrugated roofing with a nominal 16 mm rib, TRIMDEK with a nominal 29 mm rib, and KLIP-LOK variants with substantially taller ribs. Exact profiles vary by manufacturer, so the installed roof must be verified. See CUSTOM ORB, TRIMDEK and KLIP-LOK.
When is VELUX EDW the right flashing?
VELUX Australia describes EDW as the flashing for installing a single skylight into tile or corrugated iron roofing. Its side and head pieces form a gutter around the skylight so water is directed away from the opening.
That makes EDW a very good solution where the roof, pitch and VELUX model fall within its intended application. Custom flashing should not be sold simply for the sake of selling custom flashing.
| Roof / skylight situation | Typical flashing direction | What to check |
|---|---|---|
| Tile roof + FS / VS / VSE / VSS | VELUX EDW commonly suitable | VELUX size, tile profile and roof pitch. |
| Conventional corrugated iron + FS / VS / VSE / VSS | EDW or suitable custom flashing | Roof pitch, profile, water path and project preference. |
| TrimDeck + FS / VS / VSE / VSS | Custom flashing | 0–15° or 15°+ configuration, skylight size and colour. |
| Klip-Lok + FS / VS / VSE / VSS | Custom flashing | 0–15° or 15°+ configuration, roof profile and water path. |
| FCM / VCM / VCS flat-roof family | Custom-made flashing | Model/size, roof material, pitch, orientation and kerb/upstand detail. |
| Existing dome or old skylight replacement | Site-specific assessment | Existing opening, kerb, shaft, roof condition and replacement model. |
VELUX source: VELUX Australia flashing systems states EDW is for tile and corrugated iron and is not suitable for metal profiles such as Klip-Lok and Trimdek.
What happens when the roof is below 15°?
This is where it is important to separate the roof pitch from the required installation angle of the skylight.
VELUX specifies the FS, VS, VSE and VSS pitched-roof skylight families for installation from 15° to 90°. On selected low-pitch metal-roof projects, Central Skylights offers purpose-made inclined custom flashing configurations. These create an inclined base so the skylight can be presented at a suitable angle rather than simply following a roof plane below the pitched-skylight range.
15°+ roof
Example of a Central Skylights custom base flashing for a conventional 15°+ pitched-roof arrangement, subject to the specified roof profile.
0–15° metal roof
Example of a Central Skylights inclined custom flashing for a 0–15° metal roof. The raised base allows the pitched-roof VELUX to be presented at a suitable angle; project suitability still needs to be confirmed.
Corrugated
0–15°: inclined Corrugated custom flashing option.
15°+: standard-pitch custom option; EDW may also suit conventional corrugated roofing where appropriate.
TrimDeck
0–15°: inclined TrimDeck custom flashing option.
15°+: TrimDeck 15°+ custom flashing.
Klip-Lok
0–15°: inclined Klip-Lok custom flashing option.
15°+: Klip-Lok 15°+ custom flashing.
VELUX specifies FS, VS, VSE and VSS for 15°–90° installation.
FCM, VCM and VCS: custom flashing is part of the flat-roof solution
VELUX flat-roof skylights are different from FS/VS/VSE/VSS. The FCM fixed and VCS solar products are specified for roof pitches from 0° to 60°, and VELUX states that custom-made flashing is required and is not supplied with the skylight.
That makes the flashing decision especially important on modern extensions, low-slope metal roofs and replacement projects. The right arrangement depends on the skylight size, roof profile, orientation, pitch, water flow and any kerb or upstand detail.
Buying an FCM, VCM or VCS?
Do not treat the custom flashing as an afterthought. Match it to the exact four-digit VELUX size and roof profile before the roof opening is prepared.
VELUX sources: FCM fixed flat-roof skylight and VCS solar flat-roof skylight.
The flashing size follows the VELUX size
Custom flashing is not a generic “medium” or “large” accessory. It is manufactured around the dimensions and installation requirements of the skylight it is intended to serve.
VELUX C04
FS, VS, VSE and VSS C04 models share the 550 × 980 mm size. Central Skylights offers a matching C04 custom flashing with separate Corrugated, TrimDeck and Klip-Lok pitch options.
View C04 custom flashing →VELUX M08
The 780 × 1400 mm M08 size is available across pitched-roof VELUX families. The matching flashing must still be selected for the actual metal roof profile and pitch.
View M08 custom flashing →VELUX FCM / VCM / VCS 3046
The 3046 flat-roof size uses a dedicated custom flashing product with roof-profile, Colorbond and orientation choices.
View 3046 custom flashing →Replacing an old acrylic dome? The existing opening changes the conversation
Replacement work is one of the situations where buying a skylight by external dimensions alone can cause trouble.
VELUX describes FCM as suitable for replacing acrylic domes and notes that several sizes can be used as direct replacements. But many older installations have their own kerb dimensions, aged flashing details, roof patches or internal shafts. Before ordering, the existing opening and roof condition should be measured and checked.
What needs checking
- Existing dome or skylight external size
- Actual roof opening and kerb dimensions
- Roof sheet/profile around the opening
- Existing shaft size and orientation
- Signs of corrosion, previous patching or water damage
Why custom flashing helps
A purpose-made flashing can form part of the transition between the new VELUX unit and the existing roof detail. It does not automatically make every old opening compatible, but it gives the installer a designed roof interface rather than relying on an improvised on-site patch.
Read About Skylight Replacement & LeaksOur Roof Compatibility Check helps you choose before checkout
Central Skylights does not want you to buy a VELUX box and discover on installation day that the flashing does not suit the roof.
When you add a supported VELUX skylight to your cart, our online Roof Compatibility Check asks what roof the skylight is going onto and guides you toward the relevant flashing path.
The checker reads the model and size you selected.
Tile, Corrugated, TrimDeck or Klip-Lok.
0–15° or 15°+ where applicable.
Then confirm any required colour, orientation or product options before ordering.
Have these six details ready
A few minutes of checking before purchase can prevent the wrong flashing arriving on site.
VELUX model
FS, VS, VSE, VSS, FCM, VCM or VCS.
Size code
C04, C06, M08, 2246, 3046 and so on.
Roof profile
Tile, Corrugated, TrimDeck, Klip-Lok or another identified profile.
Roof pitch
Especially important when a pitched-roof VELUX is going onto a low-pitch metal roof.
Colour & orientation
Confirm Colorbond choice and portrait/landscape requirements where the product offers them.
Roof photos or drawings
For unusual roofs, replacements or uncertain details, send photos or plans before fabrication.
A VELUX + flashing package can remove one more fabrication job from site
If you already know the VELUX model, roof profile and pitch, a prefabricated matching flashing can reduce the amount of flashing design and fabrication that has to be worked out on the roof.
Send us
- VELUX model and size
- Roof-sheet profile
- Approximate pitch
- Colorbond colour
- Quantity and installation orientation
- Plans/photos for unusual roof details
We can supply
- Genuine VELUX skylights
- VELUX EDW where appropriate
- Matching custom Colorbond flashings
- Backflashing/back-tray options where specified
- Blinds and compatible accessories
- Pickup from Noble Park or selected delivery
VELUX flashing FAQ
Does every VELUX skylight need custom flashing?
No. VELUX EDW is designed for suitable tile and conventional corrugated-iron roofs. Custom flashing becomes particularly relevant for profiles such as TrimDeck and Klip-Lok, low-pitch configurations, flat-roof VELUX products and unusual replacement details.
Can VELUX EDW be used on corrugated iron?
Yes. VELUX Australia specifically lists EDW for tile and corrugated iron. The installer still needs to confirm the actual roof, pitch and installation requirements.
Can VELUX EDW be used on TrimDeck or Klip-Lok?
VELUX Australia specifically states that EDW is not suitable for metal profiles such as Trimdek and Klip-Lok. Central Skylights supplies custom flashing options for these profiles across many VELUX sizes.
What flashing do I need for a VELUX on a roof below 15°?
It depends on the VELUX family. FS, VS, VSE and VSS are pitched-roof products specified by VELUX for 15°–90° installation. For selected low-pitch Corrugated, TrimDeck and Klip-Lok projects, Central Skylights offers inclined custom flashing configurations designed to raise the skylight to a suitable angle. FCM, VCM and VCS are a separate flat-roof product family and use custom-made flashing. Always confirm the complete detail before ordering.
Does a VELUX FCM need flashing?
Yes. VELUX states that FCM requires custom-made flashing, which is not supplied with the skylight. The flashing should be matched to the FCM size and the roof construction.
Can the custom flashing match my Colorbond roof?
Many Central Skylights custom flashing products include a Colorbond colour selection. Colour is only one part of the specification; the roof profile, pitch, skylight size and orientation must also be correct.
Do I need backflashing or a back tray?
Central Skylights recommends considering backflashing or a back tray on metal roofs such as Corrugated, TrimDeck and Klip-Lok. The need and final detail depend on the roof, water flow and installation, so it should be confirmed for the project.
Can custom flashing fix an existing leaking skylight?
Sometimes flashing is part of the problem, but a leak should be diagnosed before assuming a new flashing alone will fix it. Existing roof sheets, seals, fasteners, skylight condition, previous repairs and the surrounding roof detail may all need assessment.
Can I buy the skylight and flashing without installation?
Yes. Central Skylights supplies VELUX skylights, flashings, blinds and accessories to homeowners, builders, roofers and renovators. If you prefer a complete service, installation is also available for selected Melbourne projects.
Already know the VELUX you want? Make sure the flashing matches the roof before you order.
Shop online and use our Roof Compatibility Check, or speak with Central Skylights if you are unsure about the roof profile, pitch, replacement opening or flashing configuration.
Supply only
For homeowners, builders and roofers who already have an installer. Buy the VELUX, correct flashing and accessories together.
Shop VELUX OnlineWant us to assess it?
For Melbourne installation projects, we can assess the room, roof, pitch, flashing and internal shaft before confirming the solution.
Book a Free Home VisitTechnical note: This guide explains common product-selection pathways and does not replace site assessment, VELUX installation instructions, roofing-manufacturer requirements or the installer’s responsibility to confirm structural, drainage, waterproofing and compliance requirements before installation. Product ranges and options can change; confirm current specifications before ordering.