Durolite® Webglass Durability
Webglass is a gel coated surface protected sheet, that embodies a heavy gauge woven glass mat reinforcement. The sheet strength means that wire safety mesh is not required under the sheeting. Webglass is typically used for roofing and cladding on buildings where metal substrates would quickly corrode and deteriorate at an unacceptable rate. The gel coated top surface can be translucent to allow for natural lighting or coloured to block out the light.
The useful life of Natural Lighting products is determined by their ongoing ability to allow sufficient light into the building. The following table gives a guide for the recommended use and the expected useful life based on light transmission. The long-term performance of Durolite products is enhanced by the use of a 100-micron integral gel coat surface rather than a laminated polyester film.
Natural Lighting Load Span Table
The following table provides the maximum spans for Durolite, in all the grades such as clear, HG and FG for each profile and sheet thickness limited by the ultimate limit state capacities given. The load span data is based on the number of fasteners/sheet/purlin given. The load capacities apply to both inward and outward uniformly distributed loads. The table does not cover Natural Lighting Systems intended to support concentrated loads (e.g. foot traffic). Consult Dimond for alternative systems if design consideration is to be given to concentrated load support.
Dimond Natural Lighting sheets must be fixed with screw fasteners of the same type and length for the matching metal sheeting. The fastener frequency should be specified according to the following table. Weatherlok roofing washers may be used to achieve a seal and to spread wind uplift reaction loads. For roofs with design wind loads close to the maximum values below or above 2.0 kPa, use the matching metal profiled washer and 36Ø EPDM seal. Side lap stitching and pre-drilled oversize holes may be required .
* End Span = 0.7 x Internal Span
** ULS = Ultimate Limit State Capacity
*** Span for Dimondek 630 is limited by the side lap fastener to either mid span support or purlin, at centres shown above up to a maximum number of 2 mid span supports.
- The spans given are for internal purlin spacings.
- The tabulated data does not apply to single spans. Single spans must be reduced to 0.5 x internal span.
- These spans apply where the Natural Lighting sheets are installed with both side edges supported by an adjacent metal roof.
- For continuous coverage of two or more Natural Lighting sheets we recommend reducing the spans 0.9 x Internal spans.
- U.L.S. = Ultimate Limit State Capacity.
Mid Span Support
Whenever the span capability of the Dimond Natural Lighting product does not match the purlin spacing used for the adjoining metal sheets, a mid span support must be used. The sheets must be fastened to the mid span support in the same manner as they are fastened to the purlins. Mid span supports are required to reduce sheet flutter due to wind loads and are not intended to support concentrated loads.
1⁄2 Sheet Widths Spans
The use of profiled 1⁄2 sheet widths, lapping over the side of the steel sheets, allow the spans of the selected profile Natural Lighting sheet to be increased by up to 40%, while still achieving the same ultimate limit state capacity, before needing mid supports. Half width sheets must have side lap stitching, refer table 2.4M, Section 22.214.171.124.2 of Technical Manual.
Durolite® Webglass Components
The following profiles are available in all Dimond Natural Lighting products. In addition, profiles matching most other metal roofing products may be available.
For more component information see Section 126.96.36.199.2 of Technical Manual