Polymers in Construction
Designed to provide a wealth of information on the use of plastics in construction, this handbook gives insight both to newcomers to the industry and to personnel already working in the construction sector.
TABLE OF CONTENTS Polymers in Construction
Chapter 4: Systems for Condensation Control
Arnold Janssens
4.1 Introduction
In building components, such as walls and roofs, plastics are most often used in the form of films or sheets. These films contribute to moisture control of the building envelope, by improving the air tightness, reducing the migration of water vapour from the inside environment, or preventing rain penetration. Depending on the control function of the plastic film, it is referred to as the air barrier, the wind barrier, the vapour retarder or the weather-resistive barrier.
This chapter gives a review of the use of plastics for condensation control in building components. The evolution of condensation assessment methods and control strategies developed by building scientists are compared to the condensation control measures and materials applied in building regulations and practice. This overview helps in defining performance criteria for the use of plastic films in building components.
4.2 Standard Condensation Control
4.2.1 Standard Assessment Methods
Conventional condensation control strategies focus on the control of water vapour migrating into the building envelope by diffusion under vapour pressure differences. Two control measures are common practice. The introduction of a vapour retarder at the warm side of the building envelope restricts the entry of water vapour into the construction. The application of a ventilated cavity may facilitate the escape of water vapour to the cold side of the construction. The conventional moisture performance analysis consists of defining the proper vapour retarder or the required ventilation area, using analytical calculation tools or rules of thumb. These control measures and calculation methods...
Copyright Rapra Technology Limited 2005 under license agreement with Books24x7
