Webglas GC


Webglas GC (GC = gel coated surface) is proving its worth in buildings where steel and other roofing or wall cladding materials deteriorate or corrode at an unacceptable rate. The sheet weight is 3660 grams per square metre and is reinforced with a heavy gauge woven glass mat which provides continuous strength and protection in every direction. The overall strength is such that wire safety mesh is not required. This is a particularly important benefit in aggressive and corrosive environments that can quickly destroy metal.

Where corrosion resistance is vital, complete buildings may be clad and roofed with “Webglas GC” which can be 100% opaque, or translucent to transmit natural light. For extreme environments, where high levels of acids or alkalines may occur, “Webglas GC+” which incorporates vinyl ester resins, will provide additional protection. What really sets Webglas apart from traditional building materials is its combination of strength, resistance to a wide range of chemicals and low surface erosion. The warranty covers surface erosion for 20 years.

The special resin technology used in the UV resistant surface coating is the same as that used for Zammit Roofing’s premium grade “Wonderglas GC”, now very widely used in major projects around Australia. “Webglas GC” therefore provides low maintenance roofing and cladding guaranteed for a specific lifetime.

“Webglas GC” polyester sheeting is reinforced with heavy gauge woven matting that acts a a built in safety mesh. “Webglas GC” fully complies, without restriction, to the requirements of Class 2 to Class 9 buildings of the Building Code of Australia.

Webglas GC

Polyester resin base sheet with Isopthalic NPG Gel Coated surface. Continuous woven mat reinforcement.

Webglas GC+

Vinylester resin base sheet with Isopthalic NPG Gel Coated surface. Continuous woven mat reinforcement.

All resins are UV stabilised and acrylic modified to provide excellent weather resistance. If cleaned regularly the sheeting retains its original bright appearance over many years.

Both products withstand environments that corrode or destroy metal and many plastics in a short period of time. “Webglas GC+” provides additional protection where there are high concentrations of alkalines or acids. See the “Chemical Resistance” table for details.

Available Profiles

All current profiles (see link below) such as Corrugated, Trimdek, Speed-dek, etc. plus most superseded profiles are available.


Zammit Roofing “Webglas GC” & “Webglas GC+”fully comply with the building code of Australia, Class 2 to Class 9 Buildings, including Part BI which takes into account Australian and New Zealand Standards AS1170.2:1989, AS/NZS 4256.3:1994, AS/NZS 1562.3:1996, AS4040.1:1992.

Webglas GC and GC+ fully comply with Building code specification C1.10 in particular AS1530.3: 1989.


  • Fertilizer and Agricultural Chemical Plants
  • Corrosive Chemical processing
  • Petrochemical environments
  • Wastewater Treatment
  • Marine Environments
  • Mining Industry
  • Paper and pulp manufacturing
  • Salt extraction and desalination plants
  • Power Stations
  • Skylighting where safety mesh is not desirable

Sheeting Grades

Series Weight (Kg/m2)
3660 3.66

Important: Heavier grades give the specifier the option to use Zammit Roofing sheeting in cyclonic zones, or match the span of the nominated steel roofing material (see ‘Spanning Capacity’).

Light and Heat Transmission

Grade 3660g
Light % Shading co-efficient
Ice Clear 60 0.69
Opal (white) 56 0.46
Coloured Opaque 0 0.12

Other colours can be produced to order for viable quantities, please contact your local Zammit Roofing office

Span and Fastener Table

Sheet Application Skylight Strip *Complete Roof
Profile Fastener Spacing No. of Fixings m2 1.0 kPA 2.0 kPA Maximum
Corrugated every 2nd crest 6.5 1.9m 1.5m 1.5m
5-Rib every crest 5.2 2.1m 1.6m 1.7m
Spandek every 3rd crest 3.8 2.2m 1.6m 1.6m
Super 6 every 2nd crest 3.3 2.6m 2.0m 2.1m
LT7 every 2nd crest 3.9 2.1m 1.6m 1.7m
Box Rib 5 every crest 5.4 2.2m 1.8m 1.9m

* Maxmum span for complete “Webglas GC” roof, allowing for concentrated load as per AS1170.2

Expansion Data

Materials Comparison
0°C to 40° temperature variation. Based on a sheet length of 12 metres.
Webglas GC Fibreglass Polycarbonate Steel Aluminium
Thermal Expansion 9.1mm 14.4mm 32.4mm 5.8mm 11.5mm
Thermal Co-efficient 1.9 x 10-5 cm/cm°C 3.0 x 10-5 cm/cm°C 6.75 x 10-5 cm/cm°C 1.2 x 10-5 cm/cm°C 2.4 x 10-5 cm/cm°C
Thermal conductivity 0.096 W/m.K 0.158 W/m.K 0.21 W/m.K 47.5 W/m.K 23.5 W/m.K
Density 1685 kg/m3 1400 kg/m3 1200 kg/m3 7850 kg/m3 2850 kg/m3

Physical Properties

Tensile Strength 111 Mpa
Impact Strength 10 Joules
Shear Strength 90 Mpa
Modulus of Elasticity 5300 Mpa
Compressive Strength 151 Mpa
Flexural Strength 181 Mpa
Specific Gravity 1.6
Water Absorption .2% in 24hrs./26°C
Curved Roof Radius 3660g/m2 “Corrugated” and “5-Rib”
Minimum Radius 7.5 Metres
Recommended Service Temperature Range -20° to +96°C


Fixing Details

In corrosive environments we recommend that:

  1. All fixings be Stainless Steel.
  2. All fixings be Cyclonic Assemblies.

Flashing and Capping

We recommend that all be Stainless Steel.

Technical Support

Projects involving corrosive environments often require supportive evidence regarding product suitability or manufacturers recommendations regarding the use of a particular material. Zammit Roofing can provide extensive technical support to the extent of product development if necessary. Contact your local Zammit Roofing Office if you require this service.

Chemical Resistance

Chemical Group
Webglas GC Webglas GC+ Polycarbonate P.V.C.
Acetic Acid 25% LS R LS NR
Ethanol R R NR LS
Heptanes R R R LS
Kerosene R R R LS
Turpentine R R LS LS
Urea R R LS LS
Hydrochloric Acid Conc. LS R NR LS
Hydrochloric Acid 10% R R R R
Hydrochloric Acid 40% NR R NR LS
Nitric Acid R R R LS
Oleic Acid Conc. R R R NR
Phosphoric Acid Conc. LS R NR R
Phosphoric Acid 30% LS R NR R
Sulphuric Acid 30% LS R R R
Sulphurous Acid NR R NR LS
Sulphuric Acid 3% R R LS LS
Ammonium Hydroxide 10% LS R NR R
Ammonium Sulphate LS R LS R
Sodium Hypochlorite (Chlorine) LS R R NR
Sodium Hydroxide 10%(Caustic) LS R NR R
Sodium Hydroxide 25% (Caustic) LS R NR R
Ammonium Carbonate R R NR NR
Copper Chloride R R R R
Nickel Chloride R R R R
Potassium Carbonate R R R LS
Sodium Carbonate R R R LS
Zinc Sulphate R R R R
KEY R = Recommended LS = Limited Service NR = Not Recommended