Reflective Breather Membrane for Vapor-Open Building Envelopes
Vantell VREFLECT is a high-perm reflective breather membrane developed for wall and roof assemblies where exterior weather protection, vapor permeability, mechanical strength and reflective surface performance are required in a single membrane.
Unlike conventional reflective foil membranes that are often highly vapor resistant, VREFLECT is engineered to remain vapor open. With a tested water vapor permeance of approximately 29 US perms and an equivalent air layer thickness of approximately 0.12 m, the membrane supports outward drying while maintaining resistance to liquid-water penetration.
Its reflective exterior surface provides a reflectance of ≥85%, while the reinforced membrane structure provides the strength and durability required for practical installation in timber-frame, light-gauge steel, ventilated facade and pitched roof applications.
High Vapor Permeability with Water Resistance
Vapor permeability and liquid-water resistance are different material properties. A membrane can allow water vapor to diffuse through its structure while still resisting the passage of bulk liquid water.
VREFLECT achieved approximately 29 US perms of water vapor permeance while remaining watertight under a 55 cm static water head for five hours.
This combination allows the membrane to support outward drying in vapor-open wall and roof assemblies without sacrificing exterior weather protection.
For building-envelope systems where moisture within the assembly must be able to migrate toward the exterior, this balance between vapor permeability and water resistance is especially important.
High-Reflectance Exterior Surface
VREFLECT incorporates a reflective exterior surface with a reflectance of ≥85%.
In suitable wall and roof assemblies, the reflective surface can help reduce radiant heat transfer when installed facing an appropriate adjacent air space.
Reflective performance should always be evaluated as part of the complete building-envelope design. Membrane orientation, cavity configuration, ventilation, insulation position and the presence of an air space can all influence the thermal performance of the assembly.
VREFLECT should therefore not be treated as conventional bulk insulation. Its primary role is as a vapor-permeable exterior weather membrane, with the reflective surface providing an additional radiant-control function where the assembly is appropriately designed.
Designed for Vapor-Open Wall and Roof Systems
Many modern wall and roof assemblies are designed to allow moisture to dry toward the exterior. In these systems, placing a highly vapor-resistant reflective foil on the exterior side can restrict the intended drying path.
VREFLECT provides an alternative approach by combining a reflective exterior face with high vapor permeability.
With approximately 29 US perms of vapor permeance and an equivalent air layer thickness of approximately 0.12 m, VREFLECT is suitable for assemblies where the exterior membrane must remain clearly vapor open.
This makes it suitable for wall and roof systems where the membrane is required to perform as a weather-resistive and vapor-open layer while also contributing reflective surface properties.
Reinforced for Installation Durability
Exterior membranes are exposed to significant mechanical stress during installation. Pulling, fastening, wind loading, temporary exposure and jobsite handling can all place stress on the membrane before the final cladding or roofing system is installed.
VREFLECT uses a reinforced composite construction to improve mechanical stability and installation durability.
Tested breaking force reaches 396 N in the machine direction and 214 N in the cross direction, while elongation at maximum force reaches 99% and 107% respectively.
This balance of strength and flexibility helps the membrane withstand normal handling and fastening during large-area wall and roof installation.
More Than a Reflective Surface
Reflective membranes should not be selected on reflectance alone.
A product may have a highly reflective surface but still be unsuitable for a particular wall or roof assembly if its vapor permeability, water resistance or mechanical performance does not match the requirements of the system.
VREFLECT is designed around a broader building-envelope approach that combines:
- Reflectance of ≥85%
- High vapor permeability of approximately 29 US perms
- Equivalent air layer thickness of approximately 0.12 m
- Resistance to liquid-water penetration
- Reinforced mechanical strength
- Flexibility for practical installation
- Compatibility with vapor-open wall and roof strategies
These properties allow VREFLECT to perform as more than a conventional reflective sheet. It is intended to function as part of the moisture-management, weather-protection and thermal-control strategy of the complete building envelope.
Typical Applications
- Timber-frame exterior walls
- Light-gauge steel wall systems
- Ventilated facade systems
- Rainscreen assemblies
- Pitched roof assemblies
- Tile roof systems
- Ventilated metal roof assemblies
- Prefabricated construction
- Modular construction
- Hot-climate wall and roof applications
