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Vapor Barriers Under Concrete Slabs Guidance for Selection and Location

Brian M. McCaffrey, P.E.

Course Outline

This one-hour course provides guidance on selection of vapor barriers to be placed under concrete slabs for vapor and moisture control.  The advantages and disadvantages of the location of the vapor barrier, either directly beneath the concrete slab or under a granular base and concrete slab, will also be discussed. Additionally, this course provides a template for a vapor barrier specification and discusses how a vapor barrier can earn LEED credits for building design. 

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the reader will be familiar with the following topics regarding vapor barriers:

Intended Audience

This course is intended for engineers and architects who are involved with the design of waterproofing / vapor barriers for building construction.

Benefit to Attendee

The reader will become familiar with the proper selection and location of vapor barriers beneath concrete slabs.  This will ensure that the vapor barrier not only performs as an effective barrier to moisture and other vapors, but will also maintain its physical integrity during the placement of the concrete slab.

Course Introduction

Vapor barriers are traditionally specified by architects and engineers to limit the amount of moisture that migrates into and upward through concrete slabs.  Moisture infiltration through concrete slabs has been known to cause flooring system failures, damage to the concrete slab, and growth of mold and mildew due to higher humidity levels within the building. 

More recently, vapor barriers have been used at brownfields redevelopment sites.  For sites where the source of soil or groundwater contamination cannot be completely eliminated, vapor barriers are used to prevent vapor intrusion of volatile organic compounds (VOCs) into newly constructed buildings.   

Additionally, vapor barriers are used in high radon potential areas to prevent the migration and accumulation of radon gas in buildings and homes. 

Given the many applications, a vapor barrier is one of the most critical building components used to prevent indoor air quality issues and minimize moisture-related concrete slab and flooring system failures.  Additionally, installation of a vapor barrier may help to contribute to LEED credits for buildings seeking to be certified under the U.S. Green Building Council (USGBC) for Leadership in Energy and Environmental Design (LEED).

Course Content

This course is content is in the following PDF document:

Vapor Barriers Under Concrete Slabs Guidance for Selection and Location

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.


Course Summary

At the completion of this class, the reader should understand what constitutes a vapor barrier, how to properly select a vapor barrier, the advantages and disadvantages of placing the vapor barrier either directly below the concrete slab or below a granular base and concrete slab, how to prepare a specification for a vapor barrier, and how a vapor barrier can help to earn LEED credits for building design. 


Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.