Roof & Wall Envelope
Translucent Skylight Panels for Metal Roofs
Definition: A translucent skylight panel is a roof or wall sheet made of glass-fiber reinforced polyester or polycarbonate, formed to match the profile of the adjacent steel cladding. It replaces a steel sheet in selected locations to admit diffused daylight, reducing the need for artificial lighting during the day.
Key facts
- Profiled to match the steel roof or wall sheet so laps engage correctly.
- Made from glass-fiber reinforced polyester or polycarbonate.
- Provide diffused daylight that reduces glare and daytime lighting energy.
- Usually not designed to carry the weight of a person; fall protection is required.
- UV-protective surface layers slow yellowing and loss of light transmission.
Role in the structure
Skylight panels span between purlins like the surrounding steel sheets and transfer wind, snow and maintenance loads through their fasteners into the secondary framing. Because they are generally weaker and less stiff than steel sheet, their span, fastener spacing and support details are checked separately, and they must not be treated as a walkable surface.
Benefits of daylight in steel buildings
Daylight improves visual comfort and can significantly cut daytime lighting use in warehouses, factories and sports halls. Translucent panels scatter light, spreading it evenly without the harsh shadows of clear glazing.
The area of skylights is a balance between daylight, solar heat gain and heat loss. Typical layouts place panels in regular rows across the roof, and lighting designers can model daylight levels to confirm the layout.
Materials and profiles
Glass-fiber reinforced polyester panels are widely used, affordable and available in profiles that match common steel sheets. Polycarbonate panels offer higher impact resistance and are available as single-skin profiled or multiwall sheets.
Double-skin skylights, with an insulating air space between two translucent layers, are used on insulated roofs to reduce condensation and heat loss. The panel profile must match the steel sheet precisely so side laps seal properly.
Safety on roofs with skylights
Falls through roof lights are a serious and well-known hazard. Translucent panels are generally not trafficable and may become brittle with age, so they should be protected with safety mesh, guards or fixed walkways and clearly marked on the roof.
Roof access procedures and maintenance routes should be planned so that workers never need to step on or near the skylights. Local work-at-height regulations apply and should be reviewed for each project.
Installation and weathertightness
Skylights are usually placed so that they lap under the upslope steel sheet and over the downslope sheet, with sealant at all laps. Fasteners use larger washers and pre-drilled oversized holes so the plastic can expand without cracking.
It is good practice to avoid locating skylights at end laps over a purlin where both ends would need extra sealing, and to keep them clear of valleys, gutters and roof penetrations.
Materials & coatings
- Glass-fiber reinforced polyester sheets with UV-protective surface layer.
- Polycarbonate single-skin or multiwall sheets.
- Large-diameter sealing washers and oversized-hole fixing details.
- Safety mesh or guard grilles beneath the panels.
Design considerations
- Daylight target and skylight area relative to heat gain and loss.
- Span and fastener capacity under wind suction compared with steel sheet.
- Fall protection for maintenance and roof access.
- Thermal expansion of plastic panels and fixing details.
- Compatibility with insulated roof build-ups and condensation risk.
Fabrication
- Panels are formed or extruded to match the selected steel profile.
- Lengths are cut to suit the roof layout and lap positions.
- Panels are packed flat and protected from UV exposure in storage.
Erection
- Install safety mesh before laying skylight panels where required.
- Pre-drill oversized holes and use the specified washers.
- Seal side and end laps with the specified sealant.
- Mark skylight areas and keep foot traffic away from them.
Inspection & quality
- Panels are correctly lapped and sealed with no cracks at fasteners.
- Safety mesh or guards are installed and fixed.
- Surface is free of scratches that could reduce UV resistance.
- Skylight locations match the approved roof layout.
What to include in your RFQ
- Panel material, single or double skin, and light transmission range.
- Skylight area or layout and location on the roof.
- Fall protection method beneath or above the panels.
- Matching steel profile and fixing method.
3D model & IFC of this component
Rotate the model, isolate the component and download its IFC4 file for your BIM coordination model.
IFC entity: IfcCovering (ROOFING). Illustrative geometry for coordination and learning. Final member sizes come from the project design.
Frequently Asked Questions
Can you walk on translucent roof panels?
No. They should be treated as non-trafficable and protected with mesh, guards or walkways. Never step on them during maintenance.
Do skylight panels turn yellow?
All plastics age under sunlight, but panels with a UV-protective surface layer slow yellowing and maintain light transmission for longer.
How much skylight area does a warehouse need?
It depends on use, climate and lighting goals. A daylight model or the lighting designer can recommend an area that balances daylight with heat gain.
Engineering content is general guidance. Every World Steel building is designed by qualified engineers to the code and loads of the project.
