Why Smart Moisture Control for HighPerformance Wood Buildings Matters

As wood construction accelerates across Canada, especially in mixed climate regions, managing moisture safely within high performance, airtight assemblies has become one of the most pressing challenges for design professionals. Traditional polyethylene vapour barriers, while effective at restricting winter vapour drive, can trap moisture during summer conditions, elevating the risks of mould, reduced Rvalue, and longterm structural deterioration.

MemBrain™ Smart Vapour Retarder offers a science driven solution for modern, energy efficient wood buildings. Unlike conventional Class I vapour barriers, MemBrain dynamically adapts its permeance in response to humidity within the wall cavity. When installed as a continuous interior layer and finished in accordance with typical drywall schedules, this dynamic performance, ranging from ≤60 ng/(Pa·s·m²) under dry conditions to higher vapour permeability as humidity increases, supports both airtightness and inward/outward drying potential, a critical balance for resilient wood frame assemblies.

Wood systems depend on the ability to dry, particularly where seasonal temperature swings reverse vapour drive. MemBrain’s dynamic behaviour supports the balance between airtight and vapour permeable construction, helping protect insulation performance, structural integrity, and indoor air quality.

Integrated Into the CWC Effective R Calculator

A major advantage for designers: MemBrain is included as “Smart Vapour Retarder” in the Effective R Calculator by CWC, enabling users to:

• Accurately model effective Rvalues in wood wall assemblies

• Compare smart vapour retarder with traditional polyethylene

• Evaluate insulated wall assemblies in Canadian climate zones

• Assess moisture and durability 

Users can quantify and compare performance, essential for code compliance and optimized envelope design.

Better Performing Wood Buildings, by Design

With rising expectations for durability, performance, and occupant wellness, smart vapour control is becoming fundamental to high performance wood construction. When paired with fibreglass insulation, smart vapour retarders help manage both thermal and moisture performance within the assembly.  MemBrain supports airtight, resilient, and moisture safe assemblies demanded by Canadian energy codes when installed as an interior air and vapour control layer in accordance with manufacturer instructions and National Building Code requirements.