Moisture control is paramount in passive house design, ensuring energy efficiency and indoor air quality. Walls specifically require attention to maintain optimal moisture levels.
How Much Moisture is Acceptable in Walls?
Moisture content in walls should be maintained below 15% for the following reasons:
- Structural Integrity: Excessive moisture weakens building materials.
- Thermal Performance: Moisture degrades insulation value, reducing energy efficiency.
- Indoor Air Quality: Moisture can promote mold growth, impacting indoor air quality.
Moisture Management Strategies
Passive house design employs various moisture management techniques to maintain acceptable moisture levels:
Vapor Barrier
A vapor barrier is installed on the warm side of the insulation to prevent moisture from entering the wall assembly.
Ventilated Cavity
A ventilated cavity is created between the exterior cladding and the insulation. Airflow through the cavity promotes moisture evaporation.
Hygrothermal Modeling
Hygrothermal modeling software is used to predict moisture behavior in the wall assembly. This helps design optimal moisture management strategies.
Moisture-Resistant Materials
Moisture-resistant materials, such as gypsum wallboard and exterior paint, are used to minimize moisture absorption.
Benefits of Moisture Management
Effective moisture management in passive house design offers several benefits:
- Preserves building integrity
- Improves energy efficiency
- Maintains indoor air quality
- Increases occupant comfort
- Extends building lifespan