{"title":"Retrofit Vapor Barrier Membrane","description":"\u003cp\u003eAirtightness for buildings that already exist. Our \u003ca href=\"\/en-us\/products\/passive-purple-retrofit-airtightness-5kg\"\u003eRetrofit Airtightness paints\u003c\/a\u003e go on by brush (5kg) or spray\/roller (10kg) to form a continuous vapor barrier membrane over existing walls and ceilings — no stripping back to the frame, no re-boarding. Seal junctions and penetrations with \u003ca href=\"\/en-us\/products\/passivhaus-airtight-sealant\"\u003ePassivhaus Airtight Sealant\u003c\/a\u003e and Airtight Tape as part of the same system, and bring an older building's air leakage down without gutting it. Made for EnerPHit, retrofit schemes and every drafty older home in between.\u003c\/p\u003e","products":[{"product_id":"airtight-tapes","title":"IM Fleece Airtightness Tape for Windows \u0026 Junctions","description":"\u003cp\u003e\u003cstrong\u003eIM Fleece Airtightness Tape\u003c\/strong\u003e connects window and door frames, board joints and building junctions to the surrounding air barrier. Its self-adhesive backing and plasterable fleece face help create a neat, continuous seal in new-build and retrofit construction.\u003c\/p\u003e\n\u003cp\u003eChoose a 25m roll in \u003cstrong\u003e75mm, 100mm, 150mm or 200mm width\u003c\/strong\u003e, with single-roll and box options available above. Select the width to suit the junction, the required bonded area on each surface and the movement allowance in your project detail.\u003c\/p\u003e\n\u003ch2\u003eChoose tape for the detail\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWindows and doors:\u003c\/strong\u003e connect the frame to the designed airtight layer around the reveal.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBoard and membrane joints:\u003c\/strong\u003e use where the substrate and adjoining membrane are confirmed as compatible.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRetrofit junctions:\u003c\/strong\u003e bridge changes of material after making the surfaces sound and preparing a suitable bonding area.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlastered finishes:\u003c\/strong\u003e the fleece face accepts compatible plaster or paint as specified in the installation detail.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe tape has a modified polyamide film and nonwoven fleece construction with moisture-dependent vapour resistance. Airtightness and vapour control are different requirements: confirm the complete wall or roof build-up when selecting the tape and adjoining membrane.\u003c\/p\u003e\n\u003ch2\u003ePrepare and apply correctly\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eUse sound, dry surfaces free from dust, grease and loose material. Check adhesion on the actual substrate and use a suitable primer where required.\u003c\/li\u003e\n\u003cli\u003eApply between \u003cstrong\u003e+5°C and +40°C\u003c\/strong\u003e. Do not bond to wet or damp surfaces.\u003c\/li\u003e\n\u003cli\u003ePeel back the release liner progressively, leave the required movement allowance and press the bonded area firmly with a roller.\u003c\/li\u003e\n\u003cli\u003eOverlap tape joins by at least \u003cstrong\u003e50mm\u003c\/strong\u003e and inspect corners and ends for open paths.\u003c\/li\u003e\n\u003cli\u003eConnect the tape into the adjoining air barrier using the specified compatible detail. Inspect before covering and protect exposed tape within the stated 12-month UV limit.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003eThese are selection notes, not a substitute for the \u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/files\/AIRTIGHT_FLEECE_TAPE_PRODUCT_SHEET_1.pdf?v=1771421234\"\u003eIM Fleece Tape technical data sheet\u003c\/a\u003e and \u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/files\/AIRTIGHT_FLEECE_TAPE_INSTALL_GUIDE.pdf?v=1771424163\"\u003einstallation guide\u003c\/a\u003e. Ask our technical team to confirm primer, substrate and membrane compatibility for your junction.\u003c\/p\u003e\n\u003ch2\u003ePart of a complete airtight system\u003c\/h2\u003e\n\u003cp\u003eUse the tape at suitable linear junctions and \u003ca href=\"\/en-us\/products\/passive-purple-internal-airtight-vapour-control-paint-11-4kg\"\u003ePassive Purple liquid airtight membrane\u003c\/a\u003e across the specified surrounding surface. Follow the approved interface detail, coating coverage and curing instructions. Choosing a tape alone does not guarantee a whole-building air-test result or establish a radon-resistant detail.\u003c\/p\u003e\n\u003ch2\u003eFind the right guide\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/educational\/airtightness-tape-guide\"\u003eAirtightness tape: selection, sizing and installation basics\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/educational\/why-im-fleece-airtight-tape-is-the-best-choice-for-retrofit-airtightness-window-sealing-and-passivhaus-projects\"\u003eChoosing airtight tape for windows, doors and retrofit\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/educational\/sealing-window-and-door-frames-airtight-with-fleece-tape\"\u003eHow to install fleece tape around window and door frames\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/educational\/why-airtightness-tape-peels-off\"\u003eWhy airtightness tape peels off and how to repair it\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/educational\/airtightness-tape-vs-liquid-airtight-membrane\"\u003eWhere to use tape and where to use liquid membrane\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eReady to order?\u003c\/strong\u003e Select your width and pack size above. For an unusual junction, \u003ca href=\"\/en-us\/pages\/contact\"\u003econtact our technical team\u003c\/a\u003e before installation.\u003c\/p\u003e","brand":"Intelligent Membranes","offers":[{"title":"75mm x 25m (Single Roll)","offer_id":52608799670612,"sku":"IM\/00AFT75","price":40.0,"currency_code":"GBP","in_stock":true},{"title":"75mm x 25m (Box of 5)","offer_id":52608799703380,"sku":"IM\/00AFT75-B5","price":157.5,"currency_code":"GBP","in_stock":true},{"title":"100mm x 25m (Single Roll)","offer_id":52608799736148,"sku":"IM\/00AFT100","price":50.0,"currency_code":"GBP","in_stock":true},{"title":"100mm x 25m (Box of 4)","offer_id":52608799768916,"sku":"IM\/00AFT100-B4","price":165.0,"currency_code":"GBP","in_stock":true},{"title":"150mm x 25m (Single Roll)","offer_id":52608799801684,"sku":"IM\/00AFT150","price":75.0,"currency_code":"GBP","in_stock":true},{"title":"150mm x 25m (Box of 2)","offer_id":52608799834452,"sku":"IM\/00AFT150-B2","price":111.75,"currency_code":"GBP","in_stock":true},{"title":"200mm x 25m (Single Roll)","offer_id":52608799867220,"sku":"IM\/00AFT200","price":100.0,"currency_code":"GBP","in_stock":true},{"title":"200mm x 25m (Box of 2)","offer_id":52608799899988,"sku":"IM\/00AFT200-B2","price":135.75,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/files\/Airtight_tape.png?v=1784733293"},{"product_id":"passivhaus-airtight-sealant","title":"Passivhaus Airtight Sealant - 600ml","description":"\u003cp\u003e\u003cstrong\u003ePassive Purple Sealant Tubes – Perfect for Airtight Sealing of Gaps in the Building Fabric\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePassive Purple\u003c\/strong\u003e brush in convenient sealant tubes is the ultimate solution for air-sealing gaps and cracks in the building fabric, ensuring airtightness and improved energy efficiency. This flexible, liquid-applied sealant is specifically formulated for quick and easy application, making it ideal for sealing joints, penetrations, and gaps in walls, floors, and ceilings. Designed to meet the highest airtightness standards, \u003cstrong\u003ePassive Purple\u003c\/strong\u003e helps reduce energy loss and is suitable for both new-build and retrofit projects.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey Features and Benefits:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eEfficient Air Sealing:\u003c\/strong\u003e Passive Purple sealant is ideal for sealing gaps and cracks in the building envelope, creating an airtight barrier that prevents air leakage and improves thermal performance. Perfect for use around windows, doors, service penetrations, and joints.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuick and Easy Application:\u003c\/strong\u003e Sealant tubes allow Passive Purple to be applied directly into gaps and joints using a standard caulking gun, providing precise control and a smooth, seamless finish.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVersatile Use:\u003c\/strong\u003e Suitable for a wide range of substrates including timber, concrete, brick, and plasterboard.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurable and Long-Lasting:\u003c\/strong\u003e Once applied, Passive Purple forms a flexible, durable seal that accommodates building movement and environmental changes while maintaining airtightness.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEnergy Efficiency:\u003c\/strong\u003e By eliminating air leaks, Passive Purple helps reduce energy loss, lowers heating and cooling costs, and supports energy-efficient, sustainable construction.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eWhy Choose Passive Purple in Sealant Tubes?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrecision Application:\u003c\/strong\u003e Sealant tubes allow targeted application, ensuring even the smallest gaps are effectively sealed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImproved Energy Performance:\u003c\/strong\u003e Sealing gaps with Passive Purple significantly reduces air infiltration, improving comfort and overall thermal performance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePerfect for Retrofit and New Builds:\u003c\/strong\u003e Whether sealing a new building or upgrading an existing structure, Passive Purple sealant tubes offer a practical and reliable airtightness solution.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eAchieve superior airtightness with \u003cstrong\u003ePassive Purple Sealant Tubes\u003c\/strong\u003e — an easy-to-use, flexible solution for sealing gaps in the building fabric. Ideal for improving energy efficiency and sealing joints in both new and retrofit projects, \u003cstrong\u003ePassive Purple\u003c\/strong\u003e delivers a durable, long-lasting airtight seal.\u003c\/p\u003e\n\u003cp\u003eEach sausage covers approximately \u003cstrong\u003e6 linear metres\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cdiv style=\"border-top:2px solid #b5985a;margin-top:28px;padding-top:18px;\"\u003e\n\u003ch2 style=\"color:#4a1a6e;\"\u003eTest data — worldwide\u003c\/h2\u003e\n\u003cp\u003ePassive Purple in sealant tubes is the same Passive Purple liquid airtight membrane formulation. Passive Purple has been independently tested to \u003cstrong\u003eboth ASTM and EN standards\u003c\/strong\u003e:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e🌿 \u003cstrong\u003eFrench A+ indoor-air rating \u0026amp; Finnish M1 class\u003c\/strong\u003e — very low VOC emissions (EN 16516 \/ RTS)\u003c\/li\u003e\n\u003cli\u003e🏠 \u003cstrong\u003ePassive House Institute Class A airtight\u003c\/strong\u003e — 0.02 m³\/h·m² @ 50 Pa (EN 12114)\u003c\/li\u003e\n\u003cli\u003e🔒 \u003cstrong\u003eAir barrier material\u003c\/strong\u003e — 0.02 L\/s·m² at 75 Pa (ASTM E2178)\u003c\/li\u003e\n\u003cli\u003e🔥 \u003cstrong\u003eReaction to fire\u003c\/strong\u003e — Class A to ASTM E84; Euroclass C-s1,d0 to EN 13501-1 (B-s1,d0 with FRED)\u003c\/li\u003e\n\u003cli\u003e💧 \u003cstrong\u003eWatertight\u003c\/strong\u003e (EN 14891) \u0026amp; intelligent vapour control, Sd ~0.8–40 m (EN ISO 12572)\u003c\/li\u003e\n\u003cli\u003e🧱 \u003cstrong\u003eStrong adhesion\u003c\/strong\u003e — steel 2.7, CLT 1.83, gypsum 1.6, brick 1.5 N\/mm² (EN ISO 4624)\u003c\/li\u003e\n\u003cli\u003e🦠 \u003cstrong\u003e10\/10 mould resistance\u003c\/strong\u003e (ASTM D3273) · 🛡️ radon \u0026amp; methane barrier · ♻️ EPD (EN 15804)\u003c\/li\u003e\n\u003cli\u003e✅ \u003cstrong\u003eCertificates\u003c\/strong\u003e — Passivhaus certification and BBA approval are held by Passive Purple, not by this sealant\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003ca href=\"\/en-us\/pages\/passive-purple-tested-certified\" title=\"Passive Purple Tested \u0026amp; Certified\"\u003eSee all test data \u0026amp; certifications →\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"border-top:2px solid #b5985a;margin-top:28px;padding-top:18px;\"\u003e\n\u003ch2 style=\"color:#4a1a6e;\"\u003eRelated Guides\u003c\/h2\u003e\n\u003cp\u003eHelpful guides related to this product:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/builder-forgot-the-vapour-control-layer-how-to-fix-it\" title=\"My Builder Forgot the Vapour Control Layer? Here’s How to Fix It\"\u003eMy Builder Forgot the Vapour Control Layer? Here’s How to Fix It\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/what-is-a-vapour-control-layer-vcl-explained\" title=\"What Is a Vapour Control Layer? | VCL Explained\"\u003eWhat Is a Vapour Control Layer? | VCL Explained\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/educational\/what-is-airtightness-and-why-it-matters-for-net-zero-buildings\" title=\"What is Airtightness (and Why It Matters for Net Zero Buildings)\"\u003eWhat is Airtightness (and Why It Matters for Net Zero Buildings)\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e","brand":"Intelligent Membranes","offers":[{"title":"1","offer_id":52608802292052,"sku":"IM\/00PHSS","price":12.0,"currency_code":"GBP","in_stock":true},{"title":"12","offer_id":52608802324820,"sku":"IM\/00PHSB","price":144.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/files\/Passivhaus-Sealant_-White-and-Purple_png.webp?v=1784733153"},{"product_id":"passive-purple-retrofit-airtightness-5kg","title":"Passive Purple Retrofit - Retrofit Airtightness Brush Applied Paint (5kg)","description":"\u003ch2\u003ePassive Purple Retrofit Brush – Breathable Airtightness for Existing Buildings\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePassive Purple Retrofit Brush\u003c\/strong\u003e is a fiber-reinforced, liquid-applied airtight membrane for older and solid-wall buildings that need to breathe. Brushed on internally, it seals joints, gaps, cracks and junctions against drafts and air leakage while staying \u003cstrong\u003evapor open (Sd ≈ 0.6 m)\u003c\/strong\u003e, so moisture in the wall can still dry out.\u003c\/p\u003e\n\u003ch2\u003eWhy Do Older Buildings Need a Breathable Airtight Layer?\u003c\/h2\u003e\n\u003cp\u003eSolid brick, stone and lime-plastered walls were built to manage moisture by letting it move through the wall and dry out. Sealing them with a vapor-tight layer can trap that moisture in the fabric, leading to damp, mold and decay.\u003c\/p\u003e\n\u003cp\u003ePassive Purple Retrofit stops the air leaks that cause heat loss and drafts, but still lets water vapor pass through – so the wall keeps working the way it was designed to.\u003c\/p\u003e\n\u003ch2\u003ePassive Purple or Passive Purple Retrofit?\u003c\/h2\u003e\n\u003ctable style=\"width:100%;border-collapse:collapse;margin:16px 0;\"\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth style=\"background:#4a1a6e;color:#fff;padding:10px 12px;text-align:left;\"\u003e\u003c\/th\u003e\n\u003cth style=\"background:#4a1a6e;color:#fff;padding:10px 12px;text-align:left;\"\u003ePassive Purple\u003c\/th\u003e\n\u003cth style=\"background:#4a1a6e;color:#fff;padding:10px 12px;text-align:left;\"\u003ePassive Purple Retrofit\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003e\u003cstrong\u003eVapor behavior\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003eVapor control\u003c\/td\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003eVapor open (breathable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003e\u003cstrong\u003eBest for\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003eNew builds and insulated build-ups – applied on the warm side of the insulation\u003c\/td\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003eOlder, solid-wall and breathable buildings where moisture must be able to dry out\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003e\u003cstrong\u003eAirtight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003eYes\u003c\/td\u003e\n\u003ctd style=\"padding:10px 12px;border-bottom:1px solid #e0d3ef;\"\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eNot sure which you need? Our \u003ca href=\"\/en-us\/pages\/condensation-risk-analysis\" title=\"Condensation Risk Analysis UK\"\u003econdensation risk analysis\u003c\/a\u003e will tell you, or see \u003ca href=\"\/en-us\/products\/passive-purple-internal-airtight-vapour-control-paint-11-4kg\" title=\"Passive Purple vapor control paint\"\u003ePassive Purple\u003c\/a\u003e for vapor control.\u003c\/p\u003e\n\u003ch2\u003eKey Benefits\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFiber-reinforced:\u003c\/strong\u003e spans larger joints and gaps for reliable detailing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAirtight \u0026amp; smoke-tight:\u003c\/strong\u003e stops drafts and uncontrolled air leakage.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBreathable:\u003c\/strong\u003e vapor open (Sd ≈ 0.6 m) so walls can keep drying out.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCrack-bridging:\u003c\/strong\u003e stays sealed as older buildings move.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnti-fungus:\u003c\/strong\u003e resists mold growth on the coating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLow emission:\u003c\/strong\u003e EMICODE EC2 rated.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFire-rated:\u003c\/strong\u003e Euroclass B-s1,d0.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrush applied:\u003c\/strong\u003e no specialist equipment – ideal for smaller rooms, detailing and DIY retrofits.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWhere to Use It\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eJoints, gaps and cracks in older walls\u003c\/li\u003e\n\u003cli\u003eJunctions around windows, doors, floors and ceilings\u003c\/li\u003e\n\u003cli\u003ePipe, cable and joist penetrations\u003c\/li\u003e\n\u003cli\u003eSolid brick, stone and lime-plastered walls\u003c\/li\u003e\n\u003cli\u003eSmaller rooms and period homes\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor large walls and ceilings, use \u003ca href=\"\/en-us\/products\/passive-purple-retrofit-airtightness-10kg\" title=\"Passive Purple Retrofit Spray\/Roller\"\u003ePassive Purple Retrofit Spray\/Roller (10kg)\u003c\/a\u003e for faster coverage.\u003c\/p\u003e\n\u003cdiv style=\"border-top:2px solid #b5985a;margin-top:28px;padding-top:18px;\"\u003e\n\u003ch2 style=\"color:#4a1a6e;\"\u003eTested \u0026amp; Certified — fire-rated, watertight \u0026amp; breathable\u003c\/h2\u003e\n\u003cp\u003ePassive Purple Retrofit is a product of Passive Purple External. The test results and certificates below are issued for Passive Purple External, not for the Passive Purple Retrofit product name:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e🔥 \u003cstrong\u003eReaction to fire Euroclass B-s1,d0\u003c\/strong\u003e (EN 13501-1, on A1 substrates ≥653 kg\/m³) \u0026amp; \u003cstrong\u003eASTM E84 Class A\u003c\/strong\u003e (Flame Spread 0 \/ Smoke 15)\u003c\/li\u003e\n\u003cli\u003e💧 \u003cstrong\u003eWatertight Class W1\u003c\/strong\u003e (EN 13859-2) \u0026amp; water permeability Class W3 (EN 1062-3); near-zero water absorption (EN 16302)\u003c\/li\u003e\n\u003cli\u003e🌬️ \u003cstrong\u003eBreathable \/ vapor-open\u003c\/strong\u003e — Sd ≈ 0.6 m (EN ISO 12572)\u003c\/li\u003e\n\u003cli\u003e🧱 \u003cstrong\u003eCrack-bridging\u003c\/strong\u003e A3 (23°C) \/ A4 (-10°C) (EN 1062-7) \u0026amp; CO₂ \/ carbonation barrier Class C1 (EN 1062-6)\u003c\/li\u003e\n\u003cli\u003e☀️ \u003cstrong\u003eUV-stable\u003c\/strong\u003e · low-emission \u003cstrong\u003eEMICODE EC2\u003c\/strong\u003e · anti-fungus (rating 0)\u003c\/li\u003e\n\u003cli\u003e🇬🇧 \u003cstrong\u003eKiwa BDA Agrément\u003c\/strong\u003e (BAW-21-214-P-A-UK) · Passive House component (phB) · tested to ICC-ES AC212 criteria (water-resistive barrier)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003ca href=\"\/en-us\/pages\/passive-purple-tested-certified\" title=\"Tested \u0026amp; Certified\"\u003eSee all test data \u0026amp; certifications →\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"border-top:2px solid #b5985a;margin-top:28px;padding-top:18px;\"\u003e\n\u003ch2 style=\"color:#4a1a6e;\"\u003eRelated Guides\u003c\/h2\u003e\n\u003cp\u003eHelpful guides related to this product:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/how-to-retrofit-vapour-control-without-the-mess-bba-approved-passivhaus-certified-building-control-ready\" title=\"How to Retrofit Vapor Control Without the Mess\"\u003eHow to Retrofit Vapor Control Without the Mess\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/damp-walls-two-breathable-solutions-that-actually-work\" title=\"Damp Walls? Two Breathable Solutions That Actually Work\"\u003eDamp Walls? Two Breathable Solutions That Actually Work\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/enerphit-explained-the-passivhaus-standard-for-old-buildings\" title=\"EnerPHit Explained – The Passivhaus Standard for Old Buildings\"\u003eEnerPHit Explained – The Passivhaus Standard for Old Buildings\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cp\u003e\u003cstrong\u003eQuality assurance:\u003c\/strong\u003e \u003ca href=\"\/en-us\/pages\/qa-sign-off-downloads\"\u003eDownload the free Installation \u0026amp; QA Record sign-off sheet (IM-QA-07)\u003c\/a\u003e for this product.\u003c\/p\u003e","brand":"Intelligent Membranes","offers":[{"title":"Purple","offer_id":52682700194132,"sku":"IM\/00RETB5PURPLE","price":55.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/files\/Passive_Purple_Retrofit_Brush_1.png?v=1792748153"},{"product_id":"passive-purple-retrofit-airtightness-10kg","title":"Passive Purple Retrofit - Retrofit Airtightness Spray\/Roller Paint (10kg)","description":"\u003ch2\u003ePassive Purple Retrofit – Breathable Airtightness for Existing Buildings\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePassive Purple Retrofit\u003c\/strong\u003e is a liquid-applied airtight membrane for older and solid-wall buildings that need to breathe. Sprayed or rolled on internally, it seals walls, ceilings and junctions against drafts and air leakage while staying \u003cstrong\u003evapor open (Sd ≈ 0.6 m)\u003c\/strong\u003e, so moisture in the wall can still dry out.\u003c\/p\u003e\n\u003ch2\u003eWhy Do Older Buildings Need a Breathable Airtight Layer?\u003c\/h2\u003e\n\u003cp\u003eSolid brick, stone and lime-plastered walls were built to manage moisture by letting it move through the wall and dry out. Sealing them with a vapor-tight layer can trap that moisture in the fabric, leading to damp, mold and decay.\u003c\/p\u003e\n\u003cp\u003ePassive Purple Retrofit stops the air leaks that cause heat loss and drafts, but still lets water vapor pass through – so the wall keeps working the way it was designed to.\u003c\/p\u003e\n\u003ch2\u003ePassive Purple or Passive Purple Retrofit?\u003c\/h2\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; margin: 16px 0;\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth style=\"background: #4a1a6e; color: #fff; padding: 10px 12px; text-align: left;\"\u003e\u003c\/th\u003e\n\u003cth style=\"background: #4a1a6e; color: #fff; padding: 10px 12px; text-align: left;\"\u003ePassive Purple\u003c\/th\u003e\n\u003cth style=\"background: #4a1a6e; color: #fff; padding: 10px 12px; text-align: left;\"\u003ePassive Purple Retrofit\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003e\u003cstrong\u003eVapor behavior\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003eVapor control\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003eVapor open (breathable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003e\u003cstrong\u003eBest for\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003eNew builds and insulated build-ups – applied on the warm side of the insulation\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003eOlder, solid-wall and breathable buildings where moisture must be able to dry out\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003e\u003cstrong\u003eAirtight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003eYes\u003c\/td\u003e\n\u003ctd style=\"padding: 10px 12px; border-bottom: 1px solid #e0d3ef;\"\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eNot sure which you need? Our \u003ca href=\"\/en-us\/pages\/condensation-risk-analysis\" title=\"Condensation Risk Analysis UK\"\u003econdensation risk analysis\u003c\/a\u003e will tell you, or see \u003ca href=\"\/en-us\/products\/passive-purple-internal-airtight-vapour-control-paint-11-4kg\" title=\"Passive Purple vapor control paint\"\u003ePassive Purple\u003c\/a\u003e for vapor control.\u003c\/p\u003e\n\u003ch2\u003eKey Benefits\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAirtight \u0026amp; smoke-tight:\u003c\/strong\u003e stops drafts and uncontrolled air leakage.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBreathable:\u003c\/strong\u003e vapor open (Sd ≈ 0.6 m) so walls can keep drying out.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCrack-bridging:\u003c\/strong\u003e stays sealed as older buildings move.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnti-fungus:\u003c\/strong\u003e resists mold growth on the coating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLow emission:\u003c\/strong\u003e EMICODE EC2 rated.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFire-rated:\u003c\/strong\u003e Euroclass B-s1,d0.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeamless:\u003c\/strong\u003e no tapes, laps or weak points – seals around pipes, cables and joists.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpray or roller:\u003c\/strong\u003e fast, even coverage on large walls and ceilings.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWhere to Use It\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eSolid brick and stone walls\u003c\/li\u003e\n\u003cli\u003eLime-plastered walls\u003c\/li\u003e\n\u003cli\u003ePeriod and traditional homes\u003c\/li\u003e\n\u003cli\u003eCeilings, junctions and service penetrations\u003c\/li\u003e\n\u003cli\u003eTimber-frame and mixed-construction retrofits\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eFor joints, gaps and detailing, use \u003ca href=\"\/en-us\/products\/passive-purple-retrofit-airtightness-5kg\" title=\"Passive Purple Retrofit Brush\"\u003ePassive Purple Retrofit Brush\u003c\/a\u003e, a fiber-reinforced brush grade.\u003c\/p\u003e\n\u003cdiv style=\"border-top: 2px solid #b5985a; margin-top: 28px; padding-top: 18px;\"\u003e\n\u003ch2 style=\"color: #4a1a6e;\"\u003eTested \u0026amp; Certified - fire-rated, watertight \u0026amp; breathable\u003c\/h2\u003e\n\u003cp\u003ePassive Purple Retrofit is a product of Passive Purple External. The test results and certificates below are issued for Passive Purple External, not for the Passive Purple Retrofit product name:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eReaction to fire Euroclass B-s1,d0\u003c\/strong\u003e (EN 13501-1, on A1 substrates ≥653 kg\/m³) \u0026amp; \u003cstrong\u003eASTM E84 Class A\u003c\/strong\u003e (Flame Spread 0 \/ Smoke 15)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWatertight Class W1\u003c\/strong\u003e (EN 13859-2) \u0026amp; water permeability Class W3 (EN 1062-3); near-zero water absorption (EN 16302)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBreathable \/ vapor-open\u003c\/strong\u003e — Sd ≈ 0.6 m (EN ISO 12572)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCrack-bridging\u003c\/strong\u003e A3 (23°C) \/ A4 (-10°C) (EN 1062-7) \u0026amp; CO₂ \/ carbonation barrier Class C1 (EN 1062-6)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUV-stable\u003c\/strong\u003e · low-emission \u003cstrong\u003eEMICODE EC2\u003c\/strong\u003e · anti-fungus (rating 0)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eKiwa BDA Agrément\u003c\/strong\u003e (BAW-21-214-P-A-UK) · Passive House component (phB) · tested to ICC-ES AC212 criteria (water-resistive barrier)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003ca href=\"\/en-us\/pages\/passive-purple-tested-certified\" title=\"Tested \u0026amp; Certified\"\u003eSee all test data \u0026amp; certifications →\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"border-top: 2px solid #b5985a; margin-top: 28px; padding-top: 18px;\"\u003e\n\u003ch2 style=\"color: #4a1a6e;\"\u003eRelated Guides\u003c\/h2\u003e\n\u003cp\u003eHelpful guides related to this product:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/how-to-retrofit-vapour-control-without-the-mess-bba-approved-passivhaus-certified-building-control-ready\" title=\"How to Retrofit Vapor Control Without the Mess\"\u003eHow to Retrofit Vapor Control Without the Mess\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/damp-walls-two-breathable-solutions-that-actually-work\" title=\"Damp Walls? Two Breathable Solutions That Actually Work\"\u003eDamp Walls? Two Breathable Solutions That Actually Work\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/en-us\/blogs\/news\/enerphit-explained-the-passivhaus-standard-for-old-buildings\" title=\"EnerPHit Explained – The Passivhaus Standard for Old Buildings\"\u003eEnerPHit Explained – The Passivhaus Standard for Old Buildings\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cp\u003e\u003cstrong\u003eQuality assurance:\u003c\/strong\u003e \u003ca href=\"\/en-us\/pages\/qa-sign-off-downloads\"\u003eDownload the free Installation \u0026amp; QA Record sign-off sheet (IM-QA-07)\u003c\/a\u003e for this product.\u003c\/p\u003e","brand":"Intelligent Membranes","offers":[{"title":"Purple","offer_id":52682698490196,"sku":"IM\/00RETS10PURPLE","price":119.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/files\/Passive_Purple_Retrofit_1.png?v=1792748141"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/2104\/7636\/collections\/Passive-Purple-Retrofit.png?v=1793269455","url":"https:\/\/intelligentmembranes.com\/en-us\/collections\/retrofit-vapour-barrier-membrane.oembed","provider":"Intelligent Membranes","version":"1.0","type":"link"}