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Send EmailMoisture barriers (also known as vapour control layers or vapour barriers) are critical components in building physics. Their primary function is to control the movement of water vapour through building assemblies (walls, roofs, floors) and, in some cases, to act as a liquid water barrier. Uncontrolled moisture leads to condensation, which can reduce thermal insulation performance by up to 50%, cause corrosion of metal fasteners, promote mould and fungal growth, and eventually compromise structural integrity.
There are two distinct moisture transport mechanisms:
Liquid water ingress (rain, groundwater) – usually blocked by waterproofing membranes.
Water vapour diffusion (driven by vapour pressure differences) – controlled by vapour barriers.
An effective moisture barrier must be selected based on its water vapour transmission rate (WVTR), mechanical strength, and compatibility with adjacent materials. Key technologies used in the products below include:
PU Membrane (Polyurethane): A dense, elastic film offering high water resistance but lower vapour permeability.
ePTFE Membrane (Expanded Polytetrafluoroethylene): A microporous structure that blocks liquid water while allowing water vapour to escape (“breathable”).
Nonwoven & 3D Nonwoven Textiles: Carrier layers providing mechanical strength, handling ease, and sometimes drainage or acoustic functions.
Below is a detailed technical analysis of each product listed in your catalogue.
| Code | Width (cm) | Weight (g/m²) | Construction | Description & Best Use |
|---|---|---|---|---|
| 4000 | 150 | 90 | Heat resistant nonwoven + PU membrane | Lightweight, cost-effective vapour barrier. Suitable for standard pitched roofs, wall linings, and underlayment where moderate mechanical strength is sufficient. |
| 4001 | 150 | 125 | Heat resistant nonwoven + PU membrane | Heavier version of 4000. Offers higher tear and puncture resistance. Ideal for facades, exposed roofs, or areas with higher wind loads. |
| 4002 | 150 | 125 | Heat resistant nonwoven + ePTFE bicomponent membrane | Same weight as 4001 but with breathable ePTFE. Allows trapped construction moisture to escape. Perfect for vapour-permeable wall systems, timber frames, and passive house standards. |
| 4003 | 150 | 165 | Heat resistant 3D nonwoven + ePTFE bicomponent membrane | Highest weight and 3D structure. Provides excellent acoustic absorption, high mechanical resilience, and superior breathability. Used in high-performance buildings, airports, sports halls, and industrial roofs. |
| 4004 | 150 | 85 | Knitted polyester fabric + PU membrane | Lightest product, knitted construction gives high flexibility and drape. Lower mechanical strength. Suitable for curved surfaces, temporary structures, or interior vapour control where handling ease is critical. |
| 4005 | 150 | 90 | Heat resistant nonwoven + ePTFE bicomponent membrane | Same lightweight as 4000 but with breathable ePTFE. Ideal for roofs and walls in humid climates (swimming pools, saunas, kitchens) where condensation risk is high. |
| 4008 | 150 | 165 | Heat resistant 3D nonwoven + PU membrane | Same heavy 3D structure as 4003 but with a non-breathable PU membrane. Maximum liquid water resistance and mechanical strength, but minimal vapour permeability. Best for cold storage, refrigeration buildings, and below-grade applications where vapour diffusion is not desired. |
After thorough research of standard industry catalogues and manufacturer databases, no commercially available moisture barrier products were found under the codes 4006, 4007, 4009, or 4010. Possible reasons include:
These codes may belong to a different product family (e.g., industrial packaging, medical films, or agricultural covers) not included in the building envelope catalogue.
The numbering system may have gaps for future product launches (e.g., upcoming bio-based membranes, flame-retardant versions, or recycled-content barriers).
They might represent regional or discontinued items.
If you require specific products for these codes, it is recommended to contact the original manufacturer directly for a custom solution.
Moisture barriers are used across many industries beyond construction. Below is a sector-by-sector breakdown.
Roof Underlayment (tile, metal, shingle, thatch): Secondary water protection, prevents condensation on underside of roof covering.
External Wall Insulation Systems (ETICS): Placed between insulation and outer render to stop wind-driven rain while allowing vapour escape.
Floor Screeds & Basements: Laid under concrete slabs or timber floors to stop rising damp from ground.
Timber Frame Construction: Protects wood from decay by controlling interstitial condensation.
Passive Houses & Low-Energy Buildings: High-performance vapour control layers (often with variable permeability) are mandatory.
Refrigeration & Cold Storage: Prevents moisture ingress causing ice formation and energy loss.
Food Processing Facilities: Wall and ceiling linings that resist high humidity and allow easy cleaning.
Cleanrooms & Pharmaceutical Production: Vapour barriers in walls and ceilings to maintain strict humidity control.
Flexible Packaging Laminates: Multi-layer films with aluminium or EVOH layers to protect dry foods (coffee, biscuits, milk powder) from moisture.
Desiccant-Integrated Sachets: Used inside electronic or medical device packaging to maintain low humidity during transport.
Silage Covers & Grain Storage: Heavy-duty barriers to prevent spoilage caused by environmental moisture.
Greenhouse Insulation: Transparent or translucent vapour barriers that reduce condensation drip onto plants.
Sterile Barrier Systems: Breathable but liquid-proof membranes for surgical drapes and gowns.
Wound Dressings: Advanced moisture vapour permeable films that keep wounds moist but prevent bacterial and liquid ingress.
Anti-Static Moisture Barrier Bags: Used for shipping PCBs, semiconductors, and optical lenses. Combines moisture protection with static dissipation.
Encapsulation Films: For flexible displays and solar panels – protect against humidity ingress over long service life.