The Elongation & Recovery of The IWS Membrane


Building movement occurs when the building envelope experiences thermal expansion and contraction which are caused by environmental changes, sway (which is caused by wind), seismic or other geological events. This results in both compression and tension of the materials installed in building construction. For example, when a structure heats up, the building materials from which it is built expand. Conversely, when the temperature drops, the cooling causes the materials to contract.

In the case of most building materials, including waterproofing membranes, the amount of elasticity, elongation and recovery is important in determining how a material will perform when building movement occurs. Testing for elongation is performed using a mechanical apparatus called an “Instron”. Specimens of membrane are stretched to the breaking point determining the elongation. Elongation is defined as the distance (in percent) the membrane will stretch from its original size to the point at which it breaks.


Elongation and recovery of the material used to create a waterproofing membrane will determine the length of service that can be expected with the product. Ideally, a waterproofing membrane should be strong, flexible, tear-resistant and elastic so that it can stretch to cover cracks and move with the building. The membrane should be flexible enough to conform to any substrate it is installed over. It should also be capable of turning up and over parapet walls, penetrations, and other construction installations. A good waterproofing membrane needs to provide a waterproof barrier, but it must also be able to facilitate any expected movement.

IWS Waterproofing Products have up to 1500% elongation with 90% recovery delivering exceptional performance and durability in high movement areas. With complete ASTM testing approvals and nearly 20 years as a proven performer over multiple substrates in all climates, IWS waterproofing products are Waterproofing Redefined!


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