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.

Bedford Academy's two-storey extension required a high-performance airtightness solution capable of supporting ambitious Net Zero Carbon in Operation targets. Working alongside Ashe Construction, Intelligent Membranes supplied a complete airtight building envelope system including Passive Purple, Passive Purple Brush, IM Airtight Fleece Tape, Waterproof Blue Liquid DPM and Airtight Grommets. The system created a continuous airtight and vapour control layer across multiple substrates, including masonry, steel, OSB and plasterboard, while sealing complex junctions and service penetrations. The project achieved an outstanding airtightness result of 0.43 ACH, helping reduce air leakage, improve energy efficiency, enhance occupant comfort and support long-term building performance in a modern educational facility.

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.

As part of a £7.5 million redevelopment, Dudley College transformed a redundant 1950s building into a modern Animal Studies Centre through a comprehensive deep retrofit.Intelligent Membranes supplied Passive Purple and Passive Purple Brush to create a continuous airtight and smoke-tight layer across the external masonry structure prior to the installation of an External Wall Insulation (EWI) system.The project became locally recognised as "the purple building" during construction due to the distinctive appearance of the Passive Purple membrane. Hidden behind the finished façade, the airtightness layer played a critical role in delivering an impressive airtightness result of 0.91 ACH.The completed Animal Studies Centre now provides modern educational facilities while demonstrating how existing buildings can be successfully upgraded to achieve exceptional levels of energy efficiency, airtightness and long-term building performance.

Explore how Intelligent Membranes helped Everton Heath Primary School achieve an outstanding airtightness result of just 0.03 ACH. Working alongside White Haus Timber Frame, Passive Purple and Passive Purple Brush were used to create a continuous airtight barrier throughout the building envelope, supporting high-performance construction and long-term energy efficiency. This case study showcases the benefits of timber-frame construction, modern airtightness strategies and attention to detail in delivering exceptional building performance.

The Ferndale Rise Retrofit project demonstrates how a traditional 1930s semi-detached home can be transformed into a high-performance, energy-efficient property through modern retrofit techniques.Working alongside Koru Construction and The Cambridge Building Society, Intelligent Membranes supplied Passive Purple airtight membrane and Brick Seal masonry protection to help deliver exceptional building performance.The property was stripped back to brick before being upgraded using a comprehensive deep retrofit strategy. Passive Purple was applied throughout the internal envelope to create a continuous airtight layer, while Passive Purple Brush was used at critical junctions and service penetrations. Following restoration of the external brickwork, Brick Seal was applied to provide long-term masonry protection and water repellency.The completed project achieved an impressive airtightness result of 0.54 ACH, demonstrating what can be achieved when high-performance products, expert installation and quality workmanship are combined.Products used:• Passive Purple Airtight Vapour Control Membrane• Passive Purple Brush• Brick Seal Masonry Protection Paste

Student Accommodation Protection Project: Intelligent Protect Safeguards Harrow BuildOverviewOn major construction projects, protecting valuable materials during the build phase can make or break timelines and budgets. At Harrow’s latest large-scale student accommodation development, Intelligent Membranes were brought in to safeguard over 1,500m² of glazing using our industry-leading solution: Intelligent Protect.This spray-applied, liquid protective film is one of our proudest innovations—designed to save contractors time, money, and stress while also aligning with modern sustainability goals.Why Intelligent Protect Was ChosenWindows and glazing are among the most expensive and vulnerable elements of a construction project. Damage caused by plastering, rendering, fire treatments, or even site debris can quickly spiral into huge costs, delays, and carbon-heavy replacements.Intelligent Protect offers the ultimate solution:Rapid spray application – up to 150m² protected per floor in a single day.Extreme durability – resistant to plaster, render, paint, fire treatments, dust, debris, and even hot works sparks.Peel-away removal – once construction is complete, the film is simply peeled off, leaving glazing and frames spotless with zero residue.Weatherproof protection – up to 24 months of reliable performance internally and externally.Sustainability benefits – prevents re-manufacturing, wasted labour, and repair trips, all while being VOC-free.The Harrow Student Accommodation ProjectThis high-profile Harrow development required airtight scheduling and precision installation across multiple floors. With over 1,500m² of glazing installed, Intelligent Protect was applied floor by floor immediately after window installation.Each floor, covering over 150m² of glazing, was fully protected in just one day. This rapid turnaround meant construction could continue without delay, while the glazing remained sealed, spotless, and damage-free during plastering, painting, and fireproofing.By proactively protecting these critical elements, the client avoided:Expensive window replacementsAdditional labour costsProject delays from remedial worksEmbodied carbon waste from re-manufacturingResults That Speak for ThemselvesThe use of Intelligent Protect not only safeguarded the glazing but also protected the project’s timeline, budget, and sustainability targets. By eliminating the ripple effect of delays and repairs, it became a cost-effective insurance policy for the entire build.And when construction was complete? Removal was as simple as peeling away the protective layer, leaving windows flawless and handover-ready.Intelligent Protect: Future-Proofing Student AccommodationThis project proves why Intelligent Protect is now the go-to solution for student accommodation, residential developments, and commercial builds. It keeps glazing and other vulnerable surfaces protected throughout construction—helping contractors deliver projects on time, on budget, and with reduced carbon impact.At Harrow, we showed once again that Intelligent Protect is more than a product—it’s a game-changer for modern construction.

Rebuilding for Performance: A High-Efficiency RetrofitThis London deep energy retrofit project demonstrates how existing buildings can be transformed into high-performance, energy-efficient homes through effective airtightness design and detailing.The project involved a complete internal strip-out, refurbishment and extension programme, with a strong focus on improving the building envelope and reducing uncontrolled air leakage. To achieve this, Passive Purple, Passive Purple Brush and Airtight Fleece Tape were specified to create a continuous airtight layer across masonry walls, timber structures, roof junctions, service penetrations and window interfaces.Passive Purple Brush was used to seal critical junctions, fixing points and service penetrations before the application of Passive Purple, ensuring airtight continuity throughout the building envelope. The liquid-applied system provided excellent adhesion across multiple substrates, including masonry, timber, steel and plasterboard, simplifying the airtightness strategy while maintaining robust performance.Following completion, the project achieved an exceptional airtightness result of 0.3 ACH, demonstrating the effectiveness of combining careful detailing with high-performance airtightness products.The completed retrofit now benefits from improved energy efficiency, enhanced thermal performance, reduced heat loss and increased occupant comfort, proving that outstanding airtightness results are achievable in existing buildings as well as new-build projects.

As part of a £60 million investment in its Headington Hill Campus, Oxford Brookes University developed a new Workshop Building to support engineering, manufacturing and technology education. Designed by ADP Architecture and delivered by Willmott Dixon, the facility provides state-of-the-art teaching and workshop spaces within a sustainable, high-performance building.Passive Purple was specified as the primary airtight vapour control membrane, creating a continuous airtight layer across the building envelope before the installation of External Wall Insulation (EWI). Passive Purple Brush was used to seal critical junctions and penetrations, helping maintain airtight continuity throughout the structure.The completed building demonstrates how intelligent airtightness solutions can support energy efficiency, sustainability and long-term building performance in modern educational environments.

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

Retrofit in London — Passive Purple Airtight RetrofitProject Overview A full-scale London retrofit incorporating high-performance extensions. Following a complete strip-out, Passive Purple’s liquid-applied airtight membranes were deployed to create a continuous, seamless air and vapour control barrier, enabling outstanding thermal and moisture performance.intelligentmembranes.com+14intelligentmembranes.com+14intelligentmembranes.com+14SolutionPassive Purple Brush was meticulously applied to all joints, service penetrations, and junctions.Airtight Fleece Tape reinforced critical edges and tough details.Passive Purple Internal Vapour Control Layer was spray-applied over blockwork, ceilings, and junctions, securing a monolithic airtight and vapour-tight envelope.intelligentmembranes.com+7intelligentmembranes.com+7NBS Source+7ResultsAchieved a remarkable 0.3 ACH airtightness score—well within Passivhaus standards and significantly better than UK building regulations.Delivered reduced energy demand, improved occupant comfort, and minimised condensation risk, all while preserving building longevity.intelligentmembranes.com+7intelligentmembranes.com+7intelligentmembranes.com+7“My house was a vision in purple… I’m no longer dreading my energy bills.” (Homeowner testimonial) intelligentmembranes.com+1For specification details, reference the full case study on Intelligent Membranes’ website: [Passive Purple Retrofit Installation in London – Airtightness for Energy Efficiency CONTACT US

Transforming Education Buildings: Airtight Upgrades at Dudley CollegeOverviewIn a deep retrofit of a 1950s building at Dudley College, Intelligent Membranes delivered a high-performance airtight upgrade using Passive Purple Liquid Vapour Control Membrane. By integrating modern airtightness solutions into the existing structure, the project significantly improved energy efficiency, indoor comfort, and sustainability.Project BackgroundLocated on the college’s Broadway campus, this facility underwent a sensitive retrofit aligned with sustainability goals. After repairing damaged bricks and mortar and closing redundant windows, Passive Purple Brush was applied around service penetrations and gaps. This ensured airtightness at vulnerable junctions before the liquid membrane application. NBS Manufacturing+2NBS Source+2YouTube+7intelligentmembranes.com+7barbourproductsearch.info+7Airtightness SolutionOnce detail sealing was complete, the Passive Purple Liquid Vapour Control Membrane was sprayed across all external walls, creating a seamless, airtight, and smoke-tight barrier before external wall insulation was installed. This modern construction methodology future-proofs the envelope at its core. intelligentmembranes.comResults That MatterThe project achieved an impressive 0.91 ACH (air changes per hour), far surpassing typical UK Building Regulation targets of 5.0 ACH for new builds. Given that Passive Purple was deployed independently of window or façade installations, this result is industry-leading for a retrofit of this age. intelligentmembranes.com+7intelligentmembranes.com+7barbourproductsearch.info+7 The membrane not only enhanced energy efficiency and reduced heat loss but also elevated occupant comfort, air quality, and fire safety standards.Why It ResonatesRetrofit-Friendly Accuracy: Tackles the complex, irregular junctions of older buildings with a precise and durable solution.Compliance-Driven Performance: Delivers measurable airtightness improvements in line with modern MMC best practices.System Integrity: Ensures airtightness continuity even before other envelope improvements are applied.

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?"

Unity Campus Phase 2 in South Cambridgeshire is a landmark commercial science and technology development requiring a high-performance airtight building envelope. Intelligent Membranes supplied Passive Purple, Passive Purple Brush and IM Airtight Fleece Tape to create a continuous airtight and vapour control layer across multiple substrates. The system sealed board joints, structural interfaces and window reveals, helping reduce air leakage, improve energy efficiency and support the project's sustainable construction objectives. The completed development provides modern laboratory and commercial spaces designed to deliver long-term building performance and occupant comfort.

Wester Hailes High School in Edinburgh is a £44 million Passivhaus secondary school delivered by McLaughlin & Harvey and designed by Architype. To achieve exceptional airtightness, Intelligent Membranes supplied a complete airtightness system including Passive Purple X, Passive Purple Brush, IM Airtight Fleece Tape and GOAT Sealant.Passive Purple X Brush Grade was used to seal panel joints, window openings and structural junctions before the spray application of Passive Purple X, creating a seamless, Class B fire-rated airtight vapour control layer. IM Airtight Fleece Tape provided airtight window detailing, while GOAT Sealant sealed service penetrations including pipes and cable entries.The result was an incredible 0.078 ACH pre-air test result, significantly exceeding the Passivhaus requirement of 0.6 ACH, demonstrating the effectiveness of a fully integrated airtightness strategy on one of the UK's highest-performing education 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.