Following on from the revelatory results in the 2016 tests for watertightness in ‘real life’ roofs, a further 20% of roofs were opened with their membranes tested under the same strict, independent criteria. All the results from these additional tests have reinforced the initial conclusions: Tyvek® gives lasting performance and peace of mind, where cheaper membranes fail.
The percentages speak for themselves: 94% of roofs over 20 years old fitted with Tyvek® pass with flying colours. Compare that with roofs less than 10 years old fitted with other underlays, where only 21% remain watertight. The testing demonstrates why Tyvek® is such a highly trusted product.
Concerned by multiple reports of some alternative vapour-open underlays failing in their secondary water shedding role, a couple of years ago Tyvek® instigated a thorough investigation into ‘real world’ performance. These reports put the reputation of a whole class of roofing underlays at risk, and as industry codes have yet to catch up, it was right that the market leader stepped up to investigate the issue.
Qualities such as long term water hold out – which most crucially affects the homeowner – can only be effectively assessed after exposure to natural environmental stresses, both during the build and when occupied. While ageing of underlays can positively affect vapour diffusion with increased porosity, this may adversely affect the water shedding function, should the primary covering fail. This unfortunate occurrence is becoming more prevalent in today’s increasingly stormier weather. Ultimately, the primary quality in terms of membrane longevity is watertightness – an area which presents the most risk for property, insurance, and reputations.
All membrane samples were taken from the roofs and the tests were performed by an independent expert, using the EN13859-1&2 W1 classification system for watertightness. Each specimen was exposed to a 20cm water column for 2 hours to measure not only whether any leakage occurred, but how much, over what surface area and how quickly.
This established, in crucial and revealing detail, precisely how well each underlay withstood water after 5 to 10 years in a roof, or, in the case of Tyvek®, for more than 20 years. Please visit the updated page about these ageing tests, which includes a short video, for a summary of the findings: http://tyvek.construction.dupont.com/rooftest
For more information about Tyvek® in the UK please visit: www.construction.tyvek.co.uk or call 01275 337660 (087 922 2740 in ROI)