Not all underlays are what they seem to be
Whether membranes are supplied as single layer or multi-layer, it is the functional layer which takes care of wind proofing, vapour breathability and waterproofing.
 MULTI-LAYER FUNCTIONAL LAYER |
Multi-layer underlays are composed of a very thin functional layer (3 times thinner than a human hair) laminated between external protective layers.
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| DuPont™ Tyvek® offers a functional layer which is ca. 6 to 8 times thicker than most common multi-layer products.
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When underlays are installed, ageing damage is caused by both the effects of UV radiation and temperature
Even though they cannot be seen on site, the degrading effects of exposure to UV and long periods of heat can significantly reduce the key functionality of a membrane.
Even if watertightness does not completely fail after 1 or 2 months exposure, the lifetime of a product may have already been reduced by half or even more.
The thickness and the quality of the functional layer will determine its durability (secondary water shedding function) during the construction and over the lifetime of the building. |
The ageing of an underlay is exacerbated by UV and heat
