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Moisture Vapor Transmission

Newer homes, materials and code requirements have changed the way “invisible” water (water vapor) must be managed to avoid it becoming visible in unwanted ways. Water vapor control is one of the trickiest and riskiest areas of building and energy code compliance. The old “rules of thumb” are no longer reliable or universal. This program, originally presented at IBS 2017, provides actionable prescriptive guidelines for integrated insulation and vapor control strategies. 

To download the full presentation, choose a link below. 

A comprehensive assessment of the state-of-the-art of water vapor control for modern, code-compliant, light-frame wall assemblies. The primary goal of this effort is to evaluate and reconcile existing building science knowledge and practices. An important secondary goal is to support the development of practical and comprehensive water vapor control requirements or recommendations that may be used as a basis to reach various audiences and serve multiple purposes, including building industry education and building code development.

One of the dirty little secrets that never gets talked about is that water leaks through building papers, building wraps and housewraps and runs down between them and the sheathings that they cover.

To claim that something that has holes in it can act as a water control layer is a pretty interesting argument. It is both true and untrue.

General discussion on the use of FPIS as a WRB, Air barrier or vapor retarder.

General overview of FPIS used as Continuous insulation including its history, types of FPIS and its role in performing various building envelop functions such as insulation, water resistance, air barrier and water vapor control.