ARBO ARBOShield Pro Class A W1 Breather Membrane is a high-performance vapour-permeable wall membrane developed for use in modern façade systems where fire safety, weather resistance, and airtightness are critical. It is specifically designed for high-rise and high-risk buildings, including residential blocks, schools, hospitals, and care facilities.
The membrane achieves a Class A2-s1, d0 reaction to fire in accordance with EN 13501, significantly reducing the contribution to fire spread within the external wall cavity. This makes it particularly suitable for light steel frame (SFS) construction, modular off-site builds, and other systems subject to stringent fire performance requirements. In addition to fire resistance, the membrane meets Class W1 water resistance to EN 13859-1, providing reliable protection against wind-driven rain.
ARBOShield Pro Class A W1 is vapour permeable, allowing moisture vapour to escape from the building envelope while maintaining a robust external weather barrier. With an sd value of approximately 0.08, it supports effective moisture management and helps reduce the risk of interstitial condensation within wall assemblies.
Installation must follow good practice to maintain performance. The membrane is fixed directly to sheathing boards, insulation, masonry, steel, or concrete substrates using appropriate mechanical fixings. Fixings should be spaced no more than 600mm horizontally and 500mm vertically, with stainless steel staples used on timber substrates and EPDM-washer fixings on SFS or masonry backgrounds. Vertical laps should be a minimum of 150mm, with horizontal laps of at least 100mm installed shingle-fashion from the base upwards.
All laps, penetrations, and window or door interfaces must be sealed using compatible ARBOShield Pro Class A sealing tapes to maintain water resistance and airtightness. The membrane offers high UV resistance, allowing up to nine months of continuous exposure during the construction phase without loss of performance.
When installed correctly, ARBOShield Pro Class A W1 Breather Membrane provides a durable, fire-resistant, and vapour-open layer that supports compliant, long-term façade performance in demanding construction environments.
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