Vapor Diffusion in Wood Frame Wall: Case Study of Vapor Barrier Performance.

Moisture in materials may affect its technical parameters greatly and plays significant role with close connection to durability and lifespan of building components. Moisture balance analysis and hygrothermal assessment of building components is needed to be provided during the building design stage. Recent trends in architecture integrate lightweight components with application of various foil vapor barriers to control moisture balance. While vapor barrier resistance is often decreased due to perforations in real-world application, the reliable evaluation of moisture transfer in building component is essential in thermal engineering application as well as in building science. This paper presents up to date overview of research focused on vapor diffusion through perforated materials that were conducted already in the past. While perforation of vapor barriers significantly reduces vapor resistance and air tightness corresponded to moisture balance of building element, the effect of vapor tightness decreasing is illustrated in case study based on particular wood frame wall. In this relation, a common engineering practice is compared with the complex numerical approach of heat and moisture transport on a model case with different vapor barrier permeability to identify the overall hygrothermal efficient parameters. Presented results show the importance of real vapor resistance of barriers aiming to point out the knowledge gap in the field of building civil engineering. [ABSTRACT FROM AUTHOR]