Performance and Properties for JWS Roofline Products
Most of the performance characteristics that apply to JWS roofline and cladding products can be systematically measured, this allows the creation of standards. It should be noted that, in the main, most of these standards can only apply to the components, rather than the completed assembly however we are confident that the right components installed by experts produce the right result. Thats why we offer a 10 year guarantee on our roofline installations.
Such characteristics include:
* Chemical stability
* Colour fastness
* Density durability
* Fire resistance
* Flame retardance
* Strength
* Thermal insulation
* Thermal movement
* Weather resistance
* Workability
GENERAL
JWS roofline and cladding profiles are made from cellular PVC-UE (unplasticised expanded cellular polyvinyl chloride) foam, co-extruded as a durable PVC-U skin with a rigid closed cell core. They contain no CFCs (chlorofluorocarbons) or lead and are therefore formulated to be completely non-hazardous to health. We even have customers that have setup water systems that are used for human consumption. JWS fixings are manufactured from corrosion-resistant stainless steel.
STANDARDS
JWS roofline and cladding products are manufactured in accordance with two recognised standards:
The Foam Profiles
* British Standard specification BS 7619: 1993
* Specification for extruded cellular unplasticised PVC profiles
The fasteners
* British Standard specification BS 6105: 1981
* Specification for corrosion-resistant stainless steel fasteners.
The Manufacturing Process
* The international standard for Quality Assurance
BS EN ISO 9002: 1994 (BS 5750: Pt 2).
DENSITY
The thickness of profiles varies, which affects the proportions of outer skin and inner core, so there can be no single value for density but, in general, profiles are between 450 and 600 kg/m3
STABILITY
Stability in this context is resistant to chemical and/or biological reaction. Cellular PVC-UE is not affected by liquids or other substances in everyday use, and is resistant to attack by acids and alkalis. It is generally described as being resistant to attack by wood-boring insects. It is not attacked by termites or woodworm. It does not support the growth of fungus or bacteria. It may be subject to damage by a range of chemicals, generically known as esters, ketones and solvents.
COLOUR FASTNESS
The methods of test for colour fastness contained in British Standard specification BS 1006: A03: 1978 include gradings down to a minimum value for colour change of Grade 8 – JWS white profiles all achieve either Grade 7 or 8, meaning that any fading or change in whiteness over a minimum 20 years will be within an acceptable range. JWS white profiles have demonstrated, in certified test conditions, excellent resistance to discolouration, and also to a degradation known as “pinking”, which is generally believed to be related to processes involving Titanium Dioxide and Lead stabilisers. JWS co-extrusions instead use an advanced technology lead-free stabiliser which has superior resistance to discolouration.
Coloured profiles and associated products use organic pigments, chosen for their colourfast properties. Any fading experienced will be gradual and uniform – only detectable when compared with new materials.
DURABILITY
The denseness of the outer skin ensures adequate resistance to impact, thus ensuring a highly durable surface. JWS fixings
are manufactured from Marine Grade stainless steel, the most corrosion-resistant material and thus not prone to rusting or, as a consequence, the staining of cellular profiles.
FIRE RESISTANCE
Resistance to the spread of fire can only apply to a completed assembly but not to its components, however
Profiles have been tested for compliance with the Flame Retardance requirements of British Standard BS 476:
BS 476: Pt 5: 1979 Ignitability Test – self-extinguishing;
Pt 6: 1989 Resistance to Fire Propagation – Class 1;
Pt 7:1987 Resistance to Spread of Flame – Class 1Y.
STRENGTH
The strength of JWS profiles and associated products cannot be measured as such, because strength is a characteristic of an assembly. Thus the resistance to wind loads is entirely dependent on variable factors such as profile configuration/thickness and the spacing of fixings. When fixed in accordance at the recommended spacings, the roofline and cladding systems have adequate resistance to wind loadings. Up to two storeys height, fixing spacings should not exceed 600 mm centres, and from two storeys to a maximum of five storeys, 400 mm centres.
THERMAL INSULATION
Thermal resistivity is normally referred to in terms of a U-Value. JWS profiles, due to the composition of their cellular inner core, offer thermal performance far superior to timber or other natural building products. Due to the varying nature of the profiles in terms of configuration and thickness, thermal performance can only be generalised to between 0.06 and 0.1 W/mK.
THERMAL MOVEMENT
Expressed as the coefficient of linear expansion, JWS profiles vary between 5 and 6 x 10-5 per degree Celsius. When fixed in accordance with the manufacturer’s recommendations, and in the British Isles, they perform satisfactorily. They should not be installed where ambient temperatures are likely to exceed 40 degrees, such as in close proximity to boiler flues. They should only be installed when the external air temperature is between 0 and 30 degrees. The thermal movement that occurs between day and night, sun and cloud, winter and summer should be allowed for as described in the installation recommendations.
WEATHER RESISTANCE
The impermeable external skin and closed cell structure of the core material makes JWS roofline profiles resistant to water and the elements.
WORKABILITY
JWS profiles are easily worked with conventional woodworking tools: they can be sawn, shaped, cut, drilled, routed, nailed, screwed and glued. Saws must have fine-toothed blades, and power saws should be set at their highest speed level, with carbide-tipped blades.
