Sophisticated façade design is to a major extent the defining characteristic of modern buildings. In addition to the type of material and the colour, structuring, as an essential factor in shape and form, has its own part to play in the creative design aspect. One fundamental element of this façade is offered by DuPont with their DuPont Tyvek UV Facade, a protective membrane made from a material composite of PE-HD and PP and based on flash-spinning and bonding technology. This affords reliable protection for the entire external wall construction with open joints.
Reliable protection for the entire external wall construction with open joints by means of a membrane (photos: DuPont)
The fact that DuPont Tyvek UV Facade offers reliable protection for modern, open façades has its roots primarily in the special manufacturing process in addition to its proven UV stability. This initially involves spinning numerous micro-fine endless fibres. The basic material for this is high density polyethylene (hence PE-HD) which, when liquefied in solution, is squeezed through the spinnarets under high pressure and heat. As soon as the dissolved PE-HD is discharged, the spinning medium vaporises in a flash, so producing the endless fibres – or “plexi-filaments” as they are known. The fibre bundles from 128 spinnarets are deposited on to a moving belt in several even layers extending to a width of 3m. After this comes the heat treatment where the spun fibres, rigidified and with the top and bottom layers welded together, undergo further processing to form a high quality, robust, non-woven fleece. This flash spun bond technology is, according to the company, only used in the production of DuPont Tyvek. It forms the basis for this special combination of water and wind impermeability with simultaneous vapour diffusiveness in a single functional layer.
The membrane offers water and wind impermeability with simultaneous vapour diffusiveness in a single functional layer.
High level of flexibility for planners
This means that a high degree of design freedom together with maximum possible safety in relation to building physics is available to the planner. When it comes to deployment in façades with open joints, membranes of this type are exposed to particularly high demands in terms of UV resistance because it is through the open joints that UV light impacts on the membrane throughout the entire service life of any façade.
The membrane material has been specifically designed to meet the needs of open and ventilated cladding constructions and to date is, according to the company, the only sheet material known to bear the CE mark in accordance with EN 13859-2. According to this standard, the material must be tested in the laboratory by permanently exposing it to UV radiation for 5,000h (the equivalent of almost seven months). The company states that even after such rigorous age testing, DuPont Tyvek UV Facade was found to remain fully functional, retaining more than 90% of its residual strength and 80% of its ductility.
As far as practical application is concerned, this membrane is said to provide enduring protection over a prolonged period of time for the insulation and the underlying structure of open and rear-ventilated façade with a joint width of up to 3cm. The membrane material is said to be able to withstand full exposure to the elements for up to four months without the long service life and functionality of the material being restricted thereby.
Protection of the insulation and structure in open or ventilated cladding constructions from sunlight, wind and moisture
This means that any locked-in residual moisture will be able to migrate to the outside and the insulation will at the same time be protected against the ingress of any moisture. With appropriate overlapping and bonding of the membrane once they have been placed in position, this protective function will be supported thanks to the wind-resistant characteristics of the material. To ensure improved adhesion of the membrane on site, DuPont Tyvek UV Facade can also be supplied with integrated tape as of May 2013.
www.dupont.com
www.tyvek.com
