What Type of Skylight Should You Use for a Metal Roof?

February 2026

Installing a skylight or roof window into a metal roof is perfectly achievable, but only when the roof pitch, roof type, window application, and flashing strategy are properly understood from the outset.

Metal roofs behave very differently to tiled or flat roofs. They expand and contract, shed water quickly, and rely heavily on correct detailing at penetrations. This guide explains the key considerations and the main installation methods, helping you determine what type of quality skylight can be safely installed on a metal roof. 

Step 1: Understand the Roof Pitch and Metal Roof Type 

Before selecting a skylight, you must identify:

Common metal roof types

• Standing seam metal roofs
• Corrugated metal sheets
• Trapezoidal (box profile) metal roofing 

Each profile sheds water differently and requires a specific flashing approach.

Roof pitch matters

• 15° and above - roof windows may be suitable
• Below 15° - a curb or upstand-mounted skylight is usually required 

Most roof windows are designed for pitched roofs, while skylights are better suited to low-pitch metal roofs. 

Step 2: Flashing Is the Critical Detail 

Flashing is where most failures occur on metal roofs. There are three common approaches, depending on roof pitch and structure.

Method 1: Manufacturer Flashing Kits for Metal Roofs

Companies such as The VELUX Group offer flashing kits designed specifically for metal roofing profiles. 

Key points:

• Must match the metal roof type exactly
• Suitable mainly for pitched roofs
• Always follow manufacturer pitch limits 

Some suppliers also offer standard metal roof flashing kits, which can be sourced by contact JJ Roofing Supplies directly.  

Method 2: Timber Opening With Lead Flashing Detail 

This is a widely used on-site fabricated solution, particularly where standard flashings are not suitable. 

Installation process:

1. A timber frame is formed around the structural opening 
2. Window brackets fix securely into the timber surround 
3. Lead flashing is dressed around the window perimeter 
4. Roof window cover trims seal the window into the roof structure 

This method allows greater flexibility and is commonly used on corrugated and trapezoidal roofs, provided detailing is carried out correctly. 

Method 3: Timber Upstand for Low-Pitch Roofs (Below 15°)

Where the roof pitch is below 15°, a traditional roof window should not be used. 

Instead:

• A timber upstand is constructed to the correct height 
• The upstand is weathered into the metal roof using on-site detailing 
• A flat glass skylight is installed onto the upstand after completion 

This approach is ideal for:

• Flat or near-flat metal roofs
• Extensions and commercial buildings
• High-performance double or triple glazed skylights 

Choosing the Right Skylight for a Metal Roof 

The installation method ultimately determines what skylight or roof window can be used. Factors include:

• Roof pitch 
• Metal roof profile 
• Reachability and ventilation requirements 
• Flashing and weathering strategy 

When in doubt, always consult:

• The metal roof manufacturer, who may provide standard penetration details 
• The roof window or skylight manufacturer 
• The contractor responsible for the roof build 
• Correct detailing at this stage avoids costly remedial work later. 

Final Thoughts

Installing a skylight into a metal roof is not a one-size-fits-all process. Understanding the roof construction first allows the correct product selection, flashing detail, and installation method to be specified with confidence. 

Once the installation process has been defined then you will generally have all the choices open to you as if you were fitting a roof window or a skylight into a traditional roof, to view the options please check out the JJ Roofing Roof Windows.

For technical advice, compatible products, and flashing solutions, JJ Roofing Supplies can help guide you toward the right solution for your project.