Intelligent Membranes

Protecting Bridges and Tunnels with Passive Purple ExternalWhen people think of Passive Purple External, they often picture its use in high-performance building projects — sealing external walls, improving airtightness, and boosting energy efficiency. But this intelligent, liquid-applied coating isn’t limited to homes and offices. It’s also an incredibly effective protective system for bridges, tunnels, and other large-scale infrastructure.Why Bridges and Tunnels Need Extra ProtectionConcrete may seem indestructible, but in reality it’s vulnerable to carbonation, chloride ingress, and moisture penetration. Over time, these elements can weaken the steel reinforcement inside the concrete, leading to costly repairs and safety risks. Structures like bridges and tunnels face these threats every day:Constant exposure to weather – from UV radiation and rainfall to frost and freeze-thaw cycles.Pollutants and exhaust fumes – particularly in busy tunnels and city environments.Marine or coastal conditions – where salt spray and chlorides accelerate deterioration.Without the right protective barrier, maintenance costs rise, structural integrity suffers, and the lifespan of these vital structures is reduced.How Passive Purple External Performs in Harsh EnvironmentsPassive Purple External is EN 1504-2 compliant for concrete protection, meaning it meets strict European standards for anti-carbonation performance. When applied to bridges and tunnels, it:Blocks carbon dioxide from penetrating the concrete surface, slowing carbonation and protecting embedded steel reinforcement.Repels moisture while still allowing vapour to escape, preventing trapped damp that could damage the structure from within.Resists UV, weathering, and pollutants, even in aggressive urban or industrial settings.Maintains a smooth, uniform finish that can be tinted in a range of colours to suit the structure and surrounding environment.Real-World ApplicationsFrom high-traffic overpasses to deep railway tunnels, Passive Purple External has been specified to provide long-term durability in some of the toughest conditions. For example, our application in overseas infrastructure projects — including bridge protection in coastal climates — has proven that the coating stands up to extreme weather and environmental attack while requiring minimal maintenance.The Intelligent Choice for InfrastructureWhat makes Passive Purple External stand out is that it’s not just a protective coating — it’s an intelligent membrane. Unlike many surface treatments, it remains vapour-open, allowing the structure to breathe while delivering full-scale carbonation resistance. This balance ensures both the performance and the health of the concrete over its lifetime.Bridges and tunnels are built to last — and with Passive Purple External, we make sure they stay that way.

Airtightness & Vapour Control for Bedford AcademySection: Airtightness / Vapour Control MembranesSystem: Intelligent Membranes Passive Purple Airtightness System Products: Passive Purple Internal, Passive Purple Brush, IMAF Tape (Intelligent Membranes Airtight Fleece), Waterproof Blue Liquid DPM, Airtight GrommetsProject OverviewBedford Academy’s two-storey extension, delivered by Ashe Construction for Bedford Borough Council and designed by GSS Architecture, required Passive House-grade airtightness to meet Net Zero Carbon in Operation standards. The scheme included 16 classrooms, changing rooms, dining facilities, a community café, and flexible multi-use spaces for community use.Project GoalsAchieve airtightness well beyond standard Building RegulationsEnsure continuity of the vapour control layer across multiple substrates (masonry, steel, OSB, plasterboard)Integrate airtightness measures with high-performance insulation, MVHR, ASHP, and solar PV systemsDeliver long-term durability for a high-traffic educational environmentSystem ComponentsIMAF Tape (Intelligent Membranes Airtight Fleece) – Used to bridge large gaps and seal challenging junctions between different materials, including wall-to-roof and window reveals. Applied in multiple widths (75mm–200mm).Passive Purple Brush – Fibre-reinforced liquid membrane for detailed, high-risk areas (pipe penetrations, beam ends, floor-to-wall, wall-to-steel, OSB joints, fixings).Passive Purple Internal – Spray- or roller-applied airtight and vapour control membrane to the warm side of the external walls, creating a seamless airtight layer.Waterproof Blue Liquid DPM – Applied in moisture-prone areas and under door linings for additional vapour and damp control.Airtight Grommets – Used for cables and pipe penetrations, ensuring repeatable and verifiable airtight seals.Performance AchievedAirtightness: 0.43 ACH@50Pa (Passive House levels)Vapour Control: Continuous and integrated with airtightness layerDurability: Long-term resistance to environmental factors, maintaining performance for the lifespan of the buildingEnergy Efficiency: Significant reduction in heating/cooling loads, supporting Net Zero operationInstallation MethodologySurface preparation – Substrates cleaned and primed where necessary.Moisture protection – Waterproof Blue Liquid DPM applied in damp-prone zones.Junction sealing – IMAF Tape installed at all critical interfaces.Detailing – Passive Purple Brush applied to penetrations and irregular surfaces.Full coverage – Passive Purple Internal sprayed or rolled to create a seamless airtight membrane.Penetration sealing – Airtight Grommets fitted to cables and pipes.

Case Study: Passive Purple Airtightness at Unity Campus Location: Unity Campus, Cambridge Products Used: Passive Purple External, Passive Purple Internal, Airtight White Package: Guaranteed Airtight Supply & Install Sector: Commercial / Office DevelopmentProject OverviewUnity Campus is a leading business and science hub in Cambridge, designed to deliver high-specification, sustainable workspaces. The development team required a building envelope solution that achieved superior airtightness, supported long-term energy efficiency, and aligned with the project’s low-carbon objectives.The ChallengeHigh-performance targets: Meet airtightness levels approaching Passive House standards.Mixed construction methods: A Combination of steel frame, concrete, and composite cladding.Sustainability goals: Reduce operational carbon footprint while maintaining occupant comfort.The SolutionIntelligent Membranes provided a full Guaranteed Airtight Supply & Install Package, incorporating:Passive Purple External – Applied as a vapour-open, airtight weather barrier to the external walls, allowing the building fabric to breathe while preventing moisture ingress.Passive Purple Internal – Delivered internal airtightness and vapour control, reducing heat loss and improving efficiency ratings.Airtight White – Used in visible interior areas where a clean white finish was required without compromising airtight performance.Application was carried out by our specialist team using spray, roller, and brush techniques to ensure complete coverage — even in complex junctions and service penetrations.The ResultsAchieved airtightness performance exceeding project targets.Seamless airtight layer protecting against uncontrolled airflow and moisture penetration.Improved building energy performance, contributing to sustainability goals.Efficient application, keeping the project on schedule.

Case Study: Reuben’s College – Airtightness & Vapour Control ExcellenceProject: Reuben’s CollegeLocation: Oxford, UKScope: High-performance airtightness and vapour control installationProducts Used: Passive Purple External, Passive Purple Internal, Airtight WhiteProject OverviewReuben’s College set out to achieve exceptional energy performance standards in their latest development, with a strong emphasis on airtightness, moisture control, and long-term building health. The design team wanted a solution that would not only meet compliance requirements but also exceed best-practice benchmarks for building envelope performance.Our ApproachIntelligent Membranes was brought in to supply and support the installation of our Intelligent Membrane range, combining Passive Purple External for vapour-open external airtightness, Passive Purple Internal for internal vapour control, and Airtight White for detailed airtight sealing in visible interior spaces.Passive Purple External provided a seamless, breathable barrier, allowing the structure to release moisture naturally while preventing air leakage and external moisture ingress.Passive Purple Internal created a continuous airtight layer within the building envelope, reducing heat loss and boosting efficiency ratings.Airtight White offered a discreet finish for exposed interior areas where appearance was important without compromising performance.Results AchievedExceptional airtightness results exceeding targeted performance levels.A fully breathable, vapour-controlled envelope protecting the building fabric.Reduced heat loss, contributing to improved energy efficiency and occupant comfort.Quick, efficient application using spray, roller, and brush to suit varied site conditions.Why This MattersThis project demonstrates how Intelligent Membranes’ products can be integrated into both heritage and modern educational buildings to deliver best-in-class airtightness, moisture control, and energy savings.

OverviewIn our timber frame project, achieving the airtight score we did showcases the exceptional airtightness and comprehensive sealing techniques employed. Utilizing the Passive Purple product line, we ensured a robust, flexible, and durable envelope that addresses both external and internal airtightness while providing additional protection against radon gases.BackgroundA coat of Passive Purple External Brush weatherproof membrane was first applied to all joints and junctions. This step is crucial for ensuring that these potential weak points are adequately sealed against water and air infiltration. The entire external surface, including connections, was coated to ensure a continuous and watertight barrier.SolutionsThe use of Passive Purple External Brush and Passive Purple Internal Vapour Control in this timber frame project exemplifies the importance of detailed sealing and preparation for achieving superior airtightness and energy efficiency. This project not only meets but exceeds industry standards, ensuring no air loss and enhanced thermal performance. The added benefit of a radon barrier further highlights the commitment to creating safe, healthy, and energy-efficient living spaces. This meticulous approach ensures long-term durability, weather resistance, and comfort for the building's occupants.ResultsAchieving an airtight score of 0.17 ACH is a remarkable accomplishment, significantly exceeding standard building requirements and demonstrating the efficacy of Passive Purple products. This level of airtightness dramatically reduces heating and cooling loads, leading to substantial energy savings and improved indoor comfort.Client Feedback''Not a radiator in site and I love it! We’re consistently warmer and more comfortable in general. Warm in the Winter and cool in the Summer. What’s not to like!''

A case study of the use of Airtight White intelligent airtight liquid vapor control

Over view"The devil is in the detail." This phrase rings true, especially in construction projects where achieving exceptional airtightness is critical. We ensure success by starting all our projects with Passive Purple Brush, a high-performance liquid membrane that plays a pivotal role in achieving the desired air test score.BackgroundOriented Strand Board (OSB) joints are common points of air leakage. Passive Purple Brush effectively seals these joints, preventing air infiltration and ensuring a continuous airtight barrier. By sealing all critical areas with Passive Purple Brush, we achieve consistent and reliable air test scores, often surpassing stringent standards such as Passive House requirements.SolutionsStarting our projects with Passive Purple Brush is a fundamental step in achieving exceptional airtightness and energy efficiency. By meticulously sealing all connections, OSB joints, nail heads, service penetrations, and window and door reveals, we ensure that our buildings meet and often exceed desired air test scores. This attention to detail not only enhances the building's performance but also contributes to long-term sustainability and comfort.ResultsOnce applied, Passive Purple Brush forms a robust and durable membrane that remains effective over time, even with building movements and environmental changes. 0.03 ACH (air changes per hour) was achieved on this project, largely thanks to Passive Purple Brush and it’s fibre reinforced polymer technology.

Case Study: Oxford Retrofit Airtightness UpgradeOverview with Intelligent MembranesThis retrofit project in Oxford saw Passive Purple Internal applied to the warm side of the insulation — on the outside of the property — before fitting new external wall insulation and a modern render system. This airtightness-first approach ensured the building was prepared for decades of energy-efficient performance.BackgroundThe property’s substrate was sound, making it ideal for liquid-applied membrane installation. A layer of Render Prime was applied to improve adhesion before Passive Purple application. The project was completed in just two days, with particular attention paid to airtight detailing. In retrofit projects, this detailing is vital — older buildings can have more gaps and irregularities, which we sealed using Passive Purple Brush.SolutionsApplying Passive Purple before installing external wall insulation provided:Airtight and smoke-tight barrier across all external wallsEnhanced energy efficiency by preventing heat lossImproved indoor air quality by stopping uncontrolled air movementFire safety compliance through a robust membrane layerThis method ensures a long-lasting building envelope that performs in all seasons.ResultsThe project achieved 0.4 ACH@50Pa — exceeding many new-build airtightness targets. This demonstrates the power of modern retrofit techniques to upgrade existing buildings into high-performance, low-carbon, energy-efficient homes.Client Testimonial"It was a big step but once work had started I knew it was the right decision. Passive Purple is a brilliant form of technology. Why doesn’t everyone know about this?"

OverviewIn this project, we embarked on a comprehensive renovation that included a complete strip-out and the addition of new extensions. By employing Passive Purple products and meticulous attention to detail, we achieved an impressive airtight score.BackgroundThe project began with a complete strip-out, followed by the construction of new extensions. All connections and joints were thoroughly sealed using Passive Purple Brush. This initial step is crucial for creating a continuous airtight barrier. Airtight Fleece Tape was applied around the edges to further enhance the airtightness. This tape is particularly effective in sealing difficult-to-reach areas and providing an additional layer of protection. Passive Purple Internal Vapour Control was then sprayed over the prepared surfaces, including blockwork and ceilings. This layer provides a seamless airtight and vapour control finish, essential for preventing air and moisture infiltration.SolutionsOur approach to this project highlights the importance of detailed preparation and the use of high-performance materials to achieve exceptional airtightness. By utilizing Passive Purple Brush for initial sealing and Passive Purple Internal Vapour Control for a seamless finish, we ensured that all joints, connections, and surfaces were thoroughly protected. The application of Airtight Fleece Tape and the comprehensive treatment of the loft area further reinforced the building's airtight envelope.ResultsAchieving an airtight score of 0.3 ACH is a testament to the effectiveness of the Passive Purple products and the meticulous application process. This score significantly reduces energy consumption and enhances overall building efficiency.Customer testimonial''My house was a vision in purple-inside and out! It really was amazing to watch. I’m definitely not dreading my energy bills anymore!''

Case study of Rockwool and Passive Purple together in a system and how together they are the perfect match for airtight buildings

Case Study: Passive Purple Airtightness Solution for Willmott Dixon at Oxford Brookes UniversityClient: Willmott Dixon Location: Oxford Brookes University Products Used: Passive Purple (liquid-applied intelligent membrane) Package: Guaranteed Airtight Supply & Install Sector: Education / Low-Carbon ConstructionProject OverviewOxford Brookes University embarked on a major low-carbon construction project to deliver new high-performance learning facilities. As part of the scheme, the building envelope needed to achieve airtightness levels on par with Passive House standards to reduce operational carbon and provide long-term comfort for occupants.Willmott Dixon partnered with Intelligent Membranes to deliver a complete airtightness package — from supply to installation — ensuring consistency, quality, and guaranteed performance.The ChallengeExceptional airtightness targets: Achieve near-Passive House performance levels.Complex building geometry: Multiple junctions, service penetrations, and mixed substrate types.Tight programme: Minimal disruption to the wider construction schedule.Sustainability requirements: Reduce air leakage to support the university’s low-carbon goals.The SolutionWe applied Passive Purple, our liquid-applied intelligent vapour control membrane, directly to the building fabric.Why Passive Purple was chosen:Seamless coverage – Eliminates weak points found in traditional membrane sheets.Intelligent performance – Responds to humidity and temperature changes, preventing condensation and mould risk.Speed of application – Spray, roller, and brush options for rapid coverage across varied surfaces.Vapour control – Airtight while allowing controlled breathability to protect the building fabric.Installation process:All substrates were prepared to ensure maximum adhesion.Passive Purple was spray-applied to large wall and ceiling areas, with brush application for detailed junctions.Critical connection points (windows, doors, service entries) were detailed to ensure a continuous airtight layer.The ResultsAirtightness: Achieved Passive House-level performance, exceeding initial project targets.Energy Efficiency: Significant reduction in air leakage, lowering heating and cooling demand.Durability: Long-lasting airtight seal that will perform for the lifetime of the building.Sustainability: Directly contributed to the university’s low-carbon, high-performance building objectives.Key TakeawaysThe Oxford Brookes University project showcases how Passive Purple, combined with our Guaranteed Airtight Supply & Install Package, delivers reliable, high-performance airtightness at scale. The seamless membrane application allowed Willmott Dixon to meet challenging performance goals while staying on programme, proving Passive Purple’s value in modern, sustainable construction.