Creating a robust seal around windows, doors, and SFS units is essential for ensuring a building’s integrity and performance.  To achieve the necessary air and water tightness, this requires the installation of an Interface Sealing Membrane.

Interface Sealing Membranes are specifically designed to create an effective seal against air and water ingress around windows and at the junction of different interfaces, for example, where the sheathing board edge meets the concrete frame.  They create a durable sealing solution that can accommodate thermal expansion and contraction and are also tested to minimum Class B fire classification.

Mastic is sometimes used for these sealing details but lacks the required flexibility to withstand potential movement around windows, which can result in seal failures. Over time, mastic can also become brittle, crack, or detached, compromising the integrity of the seal and allowing air and water ingress around the window.

Similarly, although breather membranes are essential for managing moisture within buildings, they are not designed to provide the level of resistance to water penetration that’s needed between windows and the substrate.  Their function is to allow moisture vapour to escape from the building whilst providing a degree of water resistance  –  not to create a water and airtight seal at the interfaces.

The specification and installation of Interface Sealing Membranes, according to the regulatory requirements, ensures that the building’s integrity, performance, and efficiency will be enhanced.