Fibre Sheet
Polycarbonate Sheet
What FRP is
Fibre sheet, also called FRP, is glass fibre reinforced plastic. It is profiled to match metal roofing so it laps into the run in the same way as a polycarbonate roof light.
The difference is in how it passes light. FRP diffuses light rather than transmitting it clearly, so the light arriving below is soft and spread rather than a bright patch that moves across the floor during the day.
Where diffusion is an advantage
Work areas where glare is a nuisance. Direct sunlight through a clear roof light onto a screen, a machine surface or an inspection bench is a real problem, and a diffusing sheet removes it while still doing the daylight job.
It is also generally the cheaper option per square foot, which matters when a large roof needs a proportion of its area glazed.
How it ages, honestly
FRP tends to yellow and lose transmission earlier than a UV protected polycarbonate sheet, and it becomes brittle with age. A sheet that was easy to handle when new can crack when someone leans on it years later, and that is a genuine safety consideration on a roof that gets maintained.
It is also much less impact resistant than polycarbonate. On a roof under trees, or one that gets walked on for maintenance, that difference is the main argument for spending more on polycarbonate instead.
Surface gel coat quality is what separates a sheet that holds up from one that degrades quickly. A thin gel coat exposes the glass fibre to weather early, and once the fibres are showing at the surface the sheet has begun to fail.
Choosing between FRP and polycarbonate
Take FRP where cost per square foot matters, where diffused light is actively wanted, and where the roof is not going to take impact or regular foot traffic.
Take polycarbonate where the roof is exposed to impact, where the sheet needs to hold its transmission for a long service life, or where anyone might have to work near it.
What to send us for a quote
The profile of the surrounding metal sheet, the sheet length and the quantity. If you are matching an existing roof, a photograph of the profile is usually enough for us to identify it.
Frequently asked questions
Is FRP cheaper than polycarbonate?
Generally yes, per square foot. It also ages faster and is far less impact resistant, so the cheaper sheet is not always the cheaper roof over its life.
Why does FRP go yellow?
Ultraviolet exposure degrading the resin at the surface. A better gel coat delays it; nothing prevents it indefinitely.
Does it give the same light as polycarbonate?
Not the same quality. FRP diffuses, giving soft even light. Polycarbonate transmits more directly. Diffusion is often the reason to choose FRP.
Is it safe to walk on?
No, and less so as it ages. FRP becomes brittle over time and can fail without much warning under a person's weight.
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