Epoxy Failures and Solutions – Vapor Transmissions

Vapor Transmissions and Floor Coatings

Concrete epoxy floor coatings are known to be sensitive to excess moisture. How this works may be surprising to you if you have not looked into it before.

Where is the moisture coming from?

Moisture problems in concrete occur in 2 different ways- moisture content in the concrete itself, and vapor transmission from below. The moisture itself is not always an issue as many epoxies can handle higher moisture in concrete. Vapor is a problem when it is transmitted to the surface. This will occur when the vapor pressure in the concrete is higher than the air at the surface.

Vapor needs to be able to move from one area to another, instead of being trapped. Vapor transmission is often seen in areas where the water table is high, as this provides a constant source of moisture from below the ground.

Why is it important to prevent vapor transmissions?

In some installations, such as in humidity controlled rooms, vapor transmission is also a critical production requirement. The need to prevent excess moisture in the room from below the concrete is particularly important. Not only is the flooring at risk, but so is the product being made there.

When vapor is trapped under a coating it can cause an adherence issue.  This will result in delamination and failure of the floor coating. You may also see blistering, peeling and moisture that will cause mildew on carpeting installed over it.

Wood flooring might see buckling or warping. Tile may crack or curl up on the edges and concrete coatings may be soft and re-emulsify.

How to prevent vapor transmission

Every concrete installation is a bit different from the others. Conditions during installation, techniques used and materials will all make each slab just a little different, but there are some similarities in how vapor transmission should be handled:

  • Ensure the concrete is cured long enough
  • Create a barrier under the concrete to prevent vapor from migrating, and make sure the edges are managed correctly
  • Control drainage in construction so water is not pooling near the building
  • Use lower quantities of water in concrete mixes

Testing is a great way to determine if vapor transmission is an issue for your surface. A few different techniques are used by professionals and can provide valuable information about your unique floor.

If vapor is a problem, Urethane Cement overlays are an excellent option.  urethane Cement can typically withstand up to 20 pounds of pressure per 1000 feet.  This is substantially greater than epoxy coatings, which typically prevent up to 3 pounds of pressure per 1000 feet.  But urethane cement can be expensive.  Another option is an epoxy moisuter mitigation system.  An epoxy moisture mitigation system can be installed.  Most moisture mitigation systems can prevent as much as 20 pounds per 1000 square feet.  And even prevent moisture from slabs that are saturated with up to 100% relative humidity.

Polished Concrete is an excellent flooring system to prevent vapor transmission.  Firstly, polished concrete doesn’t require any coatings.  Without coatings, there can be no coating failure.  Polished concrete utilizes the stone and aggregate within the concrete slab, and sweeps across the substrate with grinding stones.  Each grinding successive grinding stone gets finer and finer, so that the final product is a smooth industrial finish.

PennCoat, Inc. has been providing industrial painting, commercial painting, epoxy flooring, and polished concrete services for nearly 30 years.  Our experienced installers are trained and equipped with the proper knowledge and tools to ensure that every installation is installed efficiently and safely.  PennCoat, Inc. provides service to Pennsylvania, New Jersey, Maryland, and Delaware.  And we cover York, Lancaster, Philadelphia, Chester, Montgomery, Baltimore, Harrisburg, Dauphin, Bucks, Berks, and other counties in the surrounding area.