Deconstructing Vapor Diffusion for Building Enclosures
What is vapor diffusion?
Vapor diffusion is the movement of water vapor molecules through porous materials as a result of vapor pressure differences. It’s one of four critical elements that affects the success of your building enclosure.
Moisture can affect:
The comfort and safety of people in the building
The durability of your building enclosure
The overall performance of the building
This is how vapor typically moves:
This movement directly influences the placement of the materials within your wall assembly. Improper placement can lead to:
Vapor diffusion is generally thought of as a negative process but in reality it’s an important drying mechanism that can be used as part of the solution.