VAPOR BARRIER PRODUCTS
Uncontrolled water vapor through concrete slabs has cost building owners, designers and contractors billions of dollars. This moisture infiltration into structures contributes to the proliferation of mold, mildew and fungus and leads to flooring system failures, including adhesive failures, warping, blistering and staining. In addition, water vapor migration carrying alkali can cause structural failure of the concrete when reinforcing steel is present.
Issues Directly Related to Flooring System Failures
Many flooring systems used today form vapor barriers on top of concrete slabs and therefore trap water and alkali between the flooring system and the slab.
1999 federal mandate on VOC emissions created the need and use of water-based flooring adhesives.
Excessive moisture content of slabs leads to adhesive failures, warping, blistering, and staining.
Elevated PH levels due to water vapor driving alkali to the surface of concrete slabs cause failures of flooring adhesives and epoxy systems when the PH level exceeds the PH tolerance of the material.
Underslab Vapor Barriers
The use of underslab vapor barriers is the best method and most economical solution for controlling water vapor migration through concrete slabs. The issue of admixtures and topically applied materials does not address the issue that concrete cracks or the potential for elevated PH levels.
ASTM E 1993 and ASTM E 1745 are the two industry standards for vapor barriers and retarders under concrete slabs in contact with soil. Note that typical polyethylene film does not meet the requirements of these standards because it degrades in this environment due to the high recycled content of the material.
ASTM E 1993-98 - Standard Specification for Bituminous Water Vapor Retarders Used in Concrete with Soil or Granular Fill Under Concrete Slabs.
These products are typically specified and used in applications where the best available protection from damaging moisture is warranted. The 1993 specification materials are also the toughest available
membranes, able to best resist the rigors of placing and finishing of the concrete slab. These materials are designed for the ultimate in water vapor permeance and strength. The perm rating requirement for this standard is 0.002 perms or less. In addition, these materials are designed to be extremely durable with tensile strengths over 140 lbs. lb./in.2 and puncture resistance of 90 lbs. force.
ASTM E 1745-09 - Standard for Plastic Vapor Retarders in Contact with Soil Under Concrete Slabs.
One of the primary requirements of this standard is that the material be manufactured using virgin materials. While there are some polyethylene materials that meet this requirement, these products require fiber reinforcement to meet the tensile strength and puncture resistance requirements of the standard. The most economical material is polyolefin, which meets the requirements of the standard without the need for reinforcement. The perm rating requirement for products that meet this standard is 0.1 perms. In addition, this standard has three classes that deal with tensile strengths and puncture resistance.