The Selection of a Water Vapor Retarder

CONSIDERATIONS IN SELECTING AN EFFECTIVE WATER VAPOR RETARDER FOR YOUR PROJECT

When the proper vapor barrier/retarder is correctly installed, it will provide an economical and effective method of limiting water vapor from traveling upward through the concrete slab-on-grade or below the exterior grade.  Without the proper vapor retarder, excessive moisture will adversely affect moisture-impermeable flooring causing problems such as, warping, rotting or carpet, decay of wood floors, terrible offensive smells and fungi growth. 

Before you buy or specify a water vapor retarder, separate what's "nice" to know, from what must be known to make your decision. The process of selecting a vapor retarder includes two key steps:

Selecting a water vapor retarder best suited for your application.

A vertical wall vapor retarder may demand a more puncture resistant barrier because of design conditions such as the type of backfill material and the backfill method used. Another condition to consider is the type of compacted sub-grade used on a slab-on-grade or a sub-grade application. If sharp crushed rock is specified because of availability, or design, a more puncture-resistant vapor retarder will be required. Typically, river-run (washed rock) will cause less damage to the retarder. In general, more demanding conditions will require a Class A or B (ASTM E-1745) vapor retarder. Please refer to the chart qualifying each of our vapor retarders.

Insist the vapor retarder you're specifying meets ASTM E 1745 performance requirements! Ask yourself during the selection process:

• Has the vapor retarder been tested for resistance to deterioration from contact with soil and still maintain a 0.3 Perm or less (ASTM E 154 Section 13)?
• Does the vapor retarder meet the minimum tensile strength per classification as listed in the table below?
• Puncture strength is also a very critical factor in determining if a retarder is capable of withstanding demanding installation stress. Does the vapor retarder meet the minimum puncture strengths required of an A, B or C classification?
• Does the manufacturer provide proper certification of independent testing, correct classification and product labeling identifying class A, B or C?
• Have you determined what classification you will require in order to meet your customer's performance expectations?

ASTME 1745 Requirements

Below are some vapor barrier for your consideration.

• Poly Scrim Crawl Space Vapor Barrier:  String reinforced Crawl Space Liners
• Enkavent 6128- Radon Control
• Crawlspace 2000 : A white 20 mil string reinforced liner  12' x 100'
• Poly Scrim 12 Antimicrobial: 12 mil liner  12' x 100'

Recommended Tapes:

• • Ultra Perm Tape:  Exceptionally aggressive all weather tape
  • Butyl Seal Tape-Double Sided Tape Used to attach the plastic to the foundation walls of  the crawl space.
  • Vapor Seaming Tape Used to seam the vapor barrier plastic together in the crawl space. Minimum overlap of 6 inches.

Call for more information. Thank you!