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Class B W1 Breather Membrane
The Class B W1 Breather Membrane is a product of the ARBOSHIELD Pro® category and is used as an extremely vapour-permeable wall membrane with Class B-s1,d0 fire classification – suitable for all light steel frame and SFS type walling applications in high-rise and high-risk buildings.
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Specify Class B W1 Breather Membrane
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Unique properties of Class B W1 Breather Membrane
Helps limit the spread of fire across a façade with limited risk of smoke or burning droplets. Must be installed onto a Class A rated substrate to maintain its Class B fire performance.
Class B-s1,d0 fire classification
Class W1 resistance to water penetration
Extremely vapour permeable
Suitable for modular off-site construction
Can be installed onto any Class A rated substrate
Part of the ARBOSHIELD Pro® family of fire-resistant façade solutions
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Main Applications
Suitable for a wide range of high-rise and high-risk building types where fire performance and vapour permeability are required.
High-Rise Residential
Meets fire performance requirements for residential buildings over 18 metres (11 metres in Scotland) when installed on a Class A rated substrate.
Schools, Hospitals & Care Homes
Class B-s1,d0 fire classification makes it suitable for schools, hospitals and other high-risk occupied buildings.
Modular Off-Site Construction
Compatible with modular build programmes and off-site construction methods.
SFS & Light Steel Frame Walling
Designed for use with light steel frame and structural framing systems (SFS) in both new-build and refurbishment.
Technical Specifications & Downloads
| Description/Standard | Performance |
|---|---|
| Reaction to Fire (EN 13501) | B2-s1,d0* (*installed on Class A substrate) |
| Resistance to Water Penetration (EN 13859-1) | Class W1 |
| Tensile Strength MD (BS EN 12311-1) | 200 N/50mm BS EN 12311-1 |
| Tensile Strength CD (BS EN 12311-1) | 140 N/50mm BS EN 12311-1 |
| Flexibility at Low Temperature (EN 13859-1) | -40 °C |
| Water Vapour Transmission (ISO 12572) | 0.07 sd |
| Resistance to Nail Tearing MD (BS EN 12310-1) | 120 N BS EN 12310-1 |
| Resistance to Nail Tearing CD (BS EN 12310-1) | 140 N BS EN 12310-1 |
Associated Products
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Class A Air & Vapour Control Layer - ARBOSHIELD Pro®
ARBOSHIELD Pro® Class A Air & Vapour Control Layer is a high performance air and vapour control layer featuring a low-emissivity reflective surface designed to combine Class A2-s1,d0 fire classification with high tensile strength, enhanced thermal performance and air tightness.
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Frequently Asked Questions
The ARBOSHIELD Pro® Class B W1 Breather Membrane provides Class B-s1,d0 fire performance with Class W1 water resistance and extreme vapour permeability. It is the appropriate choice where Class B fire performance is sufficient and must be installed onto a Class A rated substrate to maintain its fire classification.
Key benefits include: Class B-s1,d0 fire classification; Class W1 resistance to water penetration; extremely vapour-permeable construction (0.07 sd); suitability for modular off-site construction; and compatibility with the full ARBOSHIELD Pro® fire-resistant façade system.
It is a complete, innovative solution for façade and apertures that brings together a ground-breaking group of products into one cohesive range. The system combines industry-leading fire safety (with up to Class A2-s1,d0 reaction to fire) with W1-rated resistance to water penetration and airtightness.
Alongside the innovative self-adhesive EPAM® perimeter seal, the complete system includes a Class A W1 Breather Membrane, a Class A Air & Vapour Control Layer, Class A High-Tack Sealing Tapes, and a Class B W1 Breather Membrane.
The system is ideal for both new build and refurbishment projects across commercial, industrial, residential, and retail buildings. Because of its consistency and ease of installation, it is also an excellent choice for modular and off-site factory-built construction projects.
ARBO® offers full technical support for specification, including NBS and Autodesk Revit integration, project specification tools and direct access to ARBO Technical Services for advice on product selection, detailing and installation guidance.
Complete solutions for your façade challenges
The ARBOSHIELD Pro® fire-resistant systems range offers a fully compatible suite of membranes, seals, and adhesives. Whether for new builds, refurbishments, high-rise residential developments, or modular construction – our cohesive product family provides the highest level of safety, weatherproofing, and compliance for your projects.
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Explore the ARBO® Product Family
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Find your contacts
Regardless of whether you are an architect and planner, property developer, industry specialist, distributor, applicator or specifier – if you have any questions about our products, services or specific construction projects, please feel free to contact the CARLISLE® contact person in your area with your technical questions. Our experts will be happy to advise you.
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