FRP Translucent Sheet for Roof Lights and Cladding

What it is

Glass fibre reinforced polyester sheet, profiled to match the surrounding metal roof sheet. Translucent, rigid, cheap, and widely used for industrial roof lights and wall lights across India.

Specification at a glance

Property	Typical specification
Composition	Polyester resin with chopped glass fibre
Weight	Commonly 1,800 — 2,400 g/m²
Surface	Gel coat or surfacing film, UV protective
Light transmission	Stated as a percentage
Profile	Matched to the adjacent metal sheet
Fire class	Named EN 13501-1 class

The specification that decides service life

FRP is sold by weight per square metre, which sets stiffness and strength, but service life is set by the surface protection. Once UV has eroded the resin at the surface, the glass fibres stand proud, the sheet goes rough and opaque, and it embrittles.

So the order should state the surfacing system, not just the gram weight.

Where it belongs

Industrial and warehouse roof lights · wall lights in shed elevations · canopies and covered walkways where cost governs · temporary and short-life structures · buildings where the roof sees little handling and impact risk is low.

Where projects go wrong

• Weight specified, protection not. The sheet then fails early and everyone blames FRP rather than the specification.
• Fixings without oversized holes. FRP moves with temperature and cracks around pinned screws.
• Sheet used as a walking surface. A genuine safety hazard.
• End laps too short for the slope, siphoning water back.
• Mixed profiles, so the FRP does not nest correctly with the metal sheet and the side lap never seals.

Standards referenced

Wind loading on roof cladding under IS 875 (Part 3). Skylight provisions under ECBC 2017. Reaction-to-fire classification to EN 13501-1.