Polymer Waterproof Breathable Membrane (Breathable Paper) is a new type of polymer waterproofing material. In terms of manufacturing process, the technical requirements for waterproof breathable membranes are significantly higher than those of conventional waterproof materials. In addition, these membranes also possess functional characteristics not found in other waterproofing materials.

Working Principle

Gas molecules have a larger spacing between them, allowing them to pass through the breathable pores of the membrane during diffusion. In contrast, liquid molecules are more densely packed than the pores and, due to surface tension, cannot pass through the membrane. This enables the membrane to be breathable yet waterproof.

Materials of the Polymer Waterproof Breathable Membrane

The membrane typically consists of three layers:

PP Spunbond Nonwoven Fabric (Top Layer)

PE Polymer Breathable Film (Middle Layer)

PP Spunbond Nonwoven Fabric (Bottom Layer)

The nonwoven fabric layers primarily enhance tensile strength and hydrostatic resistance, while protecting the middle layer. The actual breathability is mainly provided by the PE polymer breathable film in the center.

Applications Scope

Roof and Wall Waterproofing:
Suitable for use on roofs and walls of steel and wooden structures, these membranes effectively protect buildings from moisture while allowing airflow, thus improving comfort and durability.

Sealing Gaps:
Commonly used for sealing gaps in building envelopes—such as pipe interfaces, joints between doors/windows and walls, wiring boxes, roofs, and floors. Self-adhesive membranes are quick and easy to install, while non-self-adhesive versions require adhesives or heat for application.

Protecting Insulation Layers:
These membranes protect insulation layers by preventing the penetration of humid air, helping keep insulation materials dry and extending their service life.

Product Features

Waterproofing:
With micropores ranging from 0.1–1.0 microns (about 10,000 times smaller than a water droplet), the membrane effectively blocks moisture and corrosive liquids, protecting sensitive components.

Breathability:
The micropores are about 700 times larger than water vapor molecules, allowing air to pass through easily. This supports heat dissipation, prevents condensation, and balances internal and external air pressure.

Dust Resistance:
The interconnected network structure of micropores effectively blocks dust particles, with the ability to capture particles as small as 0.1 microns.

Durability and Chemical Stability:
The membrane exhibits high chemical inertness, resists extreme temperatures, UV radiation, and aging, maintaining stable performance in harsh environments.

Storage & Transportation

During transportation, membranes should be laid flat—never slanted or cross-stacked—to prevent deformation. Rolls of different specifications should be stored separately.

Store in a dry, well-ventilated environment, away from sunlight, rain, and open flames. The typical storage period is one year.

The product is packaged in woven plastic bags to protect against impacts and damage. Packaging must remain intact during storage and transport.

Rolls should be laid flat and stacked no more than four layers high. Avoid placing membranes near heat sources during both storage and transportation.

Under proper storage and transportation conditions, the shelf life is 12 months. After this period, the product should be inspected; if it meets standard requirements, it can still be used.

Application Process

Surface Cleaning:
Before applying the membrane, ensure the surface is clean, free of dust, grease, and other impurities to allow proper adhesion.

Spray Application:
Evenly spray the membrane onto the prepared surface, ensuring complete coverage without any gaps or missed spots.

Drying Time:
Allow the membrane to dry completely—typically several hours—depending on environmental conditions such as temperature and humidity.

Effect Testing:
After drying, test the waterproof and breathable properties by spraying water on the surface or wiping it with a damp cloth to check effectiveness.

Precautions for Use

Avoid Corrosive Cleaners:
Do not use acidic or alkaline cleaning agents on the membrane’s surface to prevent damage to its waterproof and breathable properties.

Prevent Scratches:
Avoid contact with sharp objects that could scratch or puncture the membrane, which would compromise its performance.

Regular Cleaning:
Clean the membrane surface periodically using a soft brush or damp cloth to remove grease and dirt.

Optimal Working Conditions:
Apply the membrane in a well-ventilated environment. Avoid spraying in overly humid, hot, or cold conditions to ensure optimal performance.