Glossary of Terms

Understanding the terminology used in FRP (Fibreglass Reinforced Polyester) roofing helps you make informed decisions. Here are the key terms explained in plain language.

A - C

Chopped Strand Mat (CSM)

A mat of randomly oriented glass fibers held together with a binder. Used as reinforcement in FRP manufacturing. Provides isotropic strength (equal strength in all directions).

End Lap

The overlap where two roofing sheets meet end-to-end along their length. Critical for weather-tight installation. Typically requires 150mm minimum overlap.

FRP (Fibreglass Reinforced Polyester)

A composite material made of glass fibers embedded in polyester resin. Also known asGRP (Glass Reinforced Plastic) or glass fiber. Combines the strength of glass with the weather resistance of plastic.

G - L

Gel Coat

The outer surface layer of an FRP sheet, typically 0.3-0.5mm thick. Provides UV resistance, weather protection, and the finished surface appearance. Can be clear or pigmented.

GSM (Grams per Square Meter)

A measure of the weight of glass fiber reinforcement per unit area. Higher GSM indicates a denser, stronger sheet. Common ranges: 300-450 (light), 600-800 (standard), 900-1200 (heavy-duty).

Light Transmission

The percentage of natural light that passes through a roofing sheet. Higher values mean more daylight inside the building. Measured according to ISO 9050. Typical FRP range: 13% to 75%.

Louver

A ventilation opening with horizontal slats that allows air passage while preventing rain entry. FRP louvers are used for daylighting and natural ventilation in industrial buildings.

M - R

Orthophthalic Polyester

The most common general-purpose polyester resin used in FRP. Good UV resistance and weatherability at economical cost. Used in Sun-Lite series.

Isophthalic Polyester

A higher-performance resin with improved chemical and water resistance compared to orthophthalic. Better corrosion resistance. Used in Moon-Lite series for chemical environments.

Profile

The cross-sectional shape of a roofing sheet. Common profiles include sinusoidal (wave), trapezoidal, and Greca/big-six. Must match or be compatible with structural purlins.

Purlins

Horizontal structural members that support the roofing sheets. Typically made of steel or timber. Spacing depends on sheet profile, thickness, and anticipated load.

S - Z

Side Lap

The overlap where two adjacent roofing sheets meet at their edges. Typically one complete corrugation or profile rib. Critical for weather-tight installation.

Vinyl Ester Resin

A premium resin combining the properties of epoxy and polyester. Excellent chemical resistance, superior adhesion to glass fibers, and good mechanical properties. Used in highly corrosive environments.

Warp

The collective term for roving, chopped strand mat, and woven roving used as reinforcement in FRP. The "skeleton" that provides structural strength.