Underslab Vapor Barriers: What is ASTM E-1745-09

Many of the vapor retarders installed under building slabs do not perform adequately due to improper placement or puncturing. Ineffective vapor retarders will not reduce permeability enough to control even the small amount of moisture it takes to interfere with the bond integrity of modern flooring systems.

All major flooring manufacturers have specifications requiring moisture tests before installation of their flooring materials. Even if new concrete is allowed to dry to the point where flooring can safely be installed, the absence or improper installation of a vapor retarder can lead to expensive failures later. Research into moisture-related flooring failures has shown a high correlation between the severity of the failure and the absence of a vapor retarder or the use of an inferior one. Some of the problems commonly associated with moisture migration through the slab include:

Who is ASTM International?

ASTM International is a globally recognized leader in the development and delivery of international voluntary consensus standards that are used around the world to improve product quality, enhance safety, facilitate market access and trade, and build consumer confidence.

What is ASTM E-1745-09?

The ASTM standard for vapor retarders under concrete slabs is ASTM E-1745-09 “Standard Specifications for Water Vapor Retarder Used in Contact with Soil or Granular Fill Under Concrete Slabs”. This standard lists three classifications which may be used to specify vapor retarders:

•  Permeance ASTM E-96 (B) (ASTM E-154 Section 7) – Determines the rate at which water vapor passes through a material 73.4°F, 50% RH
• Tensile Strength ASTM D-882 (ASTM E-154 Section 9) – Measures the ability of the material to resist a tensile-type load
• Puncture Resistance ASTM D-1709 Method B – Determines the performance of the material when impacted by an object

Our Suggestion

When looking for an underslab vapor barrier, make sure the material passes the standard for these three classifications. Don’t waste money on an inferior product or try to save money by not using a vapor retarder. Even in the most arid of climates, there is still enough moisture in the ground to cause problems.

There’s also the added moisture due to landscape irrigation systems, planters, broken plumbing pipes, and other water sources. So often it becomes a “pay me now or pay me later” with the “later” being much more expensive. No one likes to spend time and money re-doing a job. Americover’s suggestion is to do it right the first time so that you can move on to the next job.