ULTIMATE AIRTIGHT MEMBRANE FOR SWIMMING POOLS
PASSIVE PURPLE: THE ULTIMATE AIRTIGHT MEMBRANE FOR SWIMMING POOLS AND HIGH-HUMIDITY SPACES
When it comes to airtightness and vapour control in swimming pools, spa areas, and wet leisure facilities, few products can handle the challenge like Passive Purple. Constant humidity, warm air, and evaporating water create an aggressive environment that pushes materials to their limits.
At Intelligent Membranes, we tailor the performance of Passive Purple by adjusting its film thickness to match the humidity levels of the space. The result is consistent airtightness, reliable vapour resistance, and long-term durability from one product.
WHY SWIMMING POOLS NEED SPECIAL VAPOUR CONTROL
Swimming pools and wet areas maintain high internal humidity (typically 60–70% RH). This constant moisture creates vapour pressure that tries to escape through walls and ceilings. If the vapour barrier is not resistant enough, moisture can condense inside the structure, leading to mould, rot, and costly repairs.
That is why vapour control membranes in pool buildings must be carefully specified, balancing airtightness, vapour diffusion, and breathability.
TEST CONDITIONS VS. REAL-WORLD HUMIDITY
Sd values are commonly tested under 39/69% relative humidity in accordance with EN ISO 12572 laboratory standards. However, real-world environments vary significantly:
- Standard dwellings: 40–55% RH
- Bathrooms & kitchens: 55–65% RH
- Swimming pools: 60–70% RH
- Saunas / plant rooms: 70–80% RH
ADJUSTING PASSIVE PURPLE FOR POOL ENVIRONMENTS
Passive Purple is unique because its Sd value increases with film thickness. This allows vapour resistance to be tailored without changing products.
| Application | Typical RH | Dry Film Thickness (mm) | Approx. Sd Value (m) |
|---|---|---|---|
| Standard Dwellings | 40–55% | 0.4 | 14.1 |
| Swimming Pools | 60–70% | 0.6 | 21.1 |
| High-Humidity Zones | 70–80% | 0.8+ | 28+ |
By applying more Passive Purple, vapour resistance increases, keeping moisture inside the pool and out of the wall build-up.
REAL-WORLD APPLICATION
For a recent indoor pool project with air humidity around 65% RH, Passive Purple was applied at a dry film thickness of 0.6 mm. This increased the Sd value from 14 m to over 21 m, providing robust vapour control, consistent airtightness, and compatibility with renders, tile adhesives, and decorative coatings.
BENEFITS OF PASSIVE PURPLE IN POOL CONSTRUCTION
- Seamless airtight membrane with no joints or tape failures
- Adjustable Sd value by film thickness
- Fire-rated and VOC-free
- Suitable for Passivhaus, retrofit, and new-build projects
- Applied by spray, brush, or roller
INTELLIGENT AIRTIGHTNESS FOR EVERY ENVIRONMENT
Humidity varies from room to room — your airtight solution should too. Passive Purple adapts to every humidity zone, ensuring airtightness, vapour resistance, and energy efficiency are never compromised.
Whether you are working on a residential pool, hotel spa, or public leisure centre, our team can help specify the correct film thickness for optimal performance.