The long term durability and performance of a wide range of DuPont products has been demonstrated on a number of occasions, but perhaps few more dramatically than on one UK construction site towards the end of 2010. <br> <br> DuPont Tyvek Reflex, the original low emissivity breather membrane for walls, was installed in four timber frame houses in Burwell, but unfortunately the main contractor went into administration leaving the membrane exposed to the elements for a period of 33 months. <br> <br> DuPont guarantees the functionality of DuPont Tyvek Reflex after UV exposure within four months of installation. However, in this case, the recommended time period was exceeded by over 800%. Samples of the exposed material were then removed for examination by DuPont, providing outstanding results.<br> <br> Tests showed that the watertightness of the membrane was unaffected, while the emissivity performance saw a drop of only 0.03, even after 33 months of exposure to the full range of UK climatic conditions<br> <br>