Natural Light Performance - Durability

GRP plastic roof lighting materials are supplied with stabilisers in the resin and a film or gel coating to give added UV protection to the exposed surface. The covering layer will eventually break down over time, leading to yellowing and exposure of the resin to direct sunlight, which will erode the resin and expose the glass fibres. With current technology, gel coat systems erode at a slower rate and offer increased longevity and weathertightness over older film protected s

Opaque GRP sheets can be used as a cladding system in extremely corrosive environments where coated steel or aluminium products would not meet the requirements of NZBC B2/AS1 Update 4.17.7.

GRP should have a minimum thickness of 1.1 mm, but it is available up to 2.5 mm thick. Typically, low rib trapezoidal profiles and corrugated profiles are a minimum of 1800 g/m², and industrial high rib trapezoidal profiles have a minimum weight of 2,200 g/m².



GRP Weight in g/m² (Flat Sheets)

1.1 1800
1.2 2000
1.5 2400
1.9 2800
2.0 3050
2.5 3660
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Polycarbonate is a tough, clear thermoplastic polymer with a co-extruded UV resistant top layer to improve UV stability. It is available in thicknesses from 0.8 mm to 2.0 mm.

Polycarbonate sheets must not be fitted above sprinklers as they can drop out in a fire and interfere with the sprinkler’s function.

As all types of roof lights have an inert surface, discharge of condensation from them onto unpainted galvanised surfaces will cause premature corrosion. (See Inert Catchment).  Such corrosion will not occur when roof lights discharge onto a painted galvanised surface, painted or unpainted aluminium/zinc, or aluminium surfaces.



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