Due to energy code changes, better enforcement, and as a matter of good practice, we are making buildings more and more airtight. Humidity and condensation control go hand in hand with mechanical ventilation of conditioned space. This presentation will focus on the increasing number of interior wall assemblies (and roofs) that are experiencing excessive condensation damage and specific cases that our team of forensic experts has observed over the past several years.

Understanding and predicting moisture movement within and through exterior wall systems is one of the most important factors affecting enclosure performance. Condensation issues can occur with or without designed air barriers, and it is important to understand the role ventilation plays in the design.

This presentation will include forensic studies of moisture movement and condensation control utilizing data loggers to measure moisture movement. The author will review WUFI® analysis of actual assemblies in actual buildings to understand how buildings behave in real-time versus design parameters. Discussion will include mechanical ventilation involved in condensation control, including make-up air versus exhaust. This presentation will also provide an analysis of code requirements versus actual system performance.

The nature of these failures includes design defects and failures related to changes the industry has made for energy efficiency, including cost-cutting measures and system design issues.