Vapor Barriers Under Concrete Slabs - How to Select and Locate
- By Usman Naseer
- 0
Course Description
Concrete is naturally porous and acts like a sponge, drawing moisture from the ground upward through capillary action. Vapor, not liquid water, is the primary cause of floor covering failures such as blistering, peeling adhesives, and warping of luxury vinyl tile or hardwood. A properly selected and located vapor barrier stops this upward vapor drive before it reaches the concrete slab.
What you'll learn in this course?
Differentiate between a vapor barrier and a vapor retarder based on ASTM E1745 classifications.
Identify the three critical locations for placing vapor barriers relative to the slab and sub-base.
Select the appropriate material thickness and permeance based on site ground conditions and floor covering type.
Calculate the required overlap, sealing, and penetration detailing to achieve a continuous barrier.
Troubleshoot common field failures caused by incorrect selection or placement of vapor barriers.
Course Curriculum
- The Hidden Problem – Vapor Migration
- Why Concrete Slabs Are Not Waterproof
- The Difference Between Liquid Water and Water Vapor
- Consequences of Vapor Barrier Failure
- Key Terminology for This Course
- Overview of ASTM E1745 – The Gold Standard
- ASTM E1745 – Three Classes Defined
- Common Materials – Polyethylene (PE)
- Common Materials – EVOH (Ethylene Vinyl Alcohol)
- Common Materials – Asphalt-Modified Polyethylene
- Materials to Avoid (False Economy)
- Choosing Between 10 mil, 15 mil, and 30 mil
- Three Possible Locations for the Barrier
- Location 1 – Directly Under Slab (Most Common)
- Location 2 – Within the Slab (Sandwich Method)
- Location 3 – Below a Capillary Break (Under Gravel)
- How to Select the Correct Location – Decision Matrix
- The Importance of a Capillary Break Above the Barrier
- Common Mistake – Placing Barrier Over the Sub-Base Only
- Vapor Barrier and Radon Gas
- Permeance as the Primary Selection Criterion
- Puncture Resistance – The Most Common Field Failure
- Tensile Strength and Tear Resistance
- Chemical Resistance to Concrete Alkalis
- UV Stability for Exposed Storage
- Matching Barrier to Floor Covering Type
- Cost-Benefit Analysis of Upgrading from Class B to Class A
- Overlap Requirements – Minimum 6 Inches for Concrete Slabs
- Sealing to Penetrations (Pipes, Columns, Conduits)
- Sealing to Foundation Walls and Edge Forms
- Repairing Punctures and Tears in the Field
- Quality Control – Pre-Pour Inspection Checklist
- Protecting the Barrier During Rebar Placement
- Concrete Placement Over the Barrier – Best Practices
- Common Installation Mistakes to Avoid
- Case Study 1 – Luxury Apartment with Blistering Vinyl
- Case Study 2 – Hospital Operating Room with Epoxy Failure
- Case Study 3 – Warehouse with No Barrier (Successfully
- Key Takeaways from Failures
- Summary of Key Points
- Vapor Barriers Under Concrete Slabs - How to Select and Locate
Usman Naseer
3 
Course includes:
Levelintermediate
Duration180 minutes
Lessons41
Quizzes0
CertificationsYes
Enrolled0