This is a continuation of advantages of epoxy vapor barrier installations for existing slabs that help mediate moisture transmission. If high RH readings are present in existing slabs and require epoxy vapor barriers a couple of risks should be considered.
One of the biggest risk is prior surface contamination. In many of our epoxy flooring projects we work with owners that may have an automotive shop or industrial space that has heavy concrete surface contamination. Epoxy flooring installations are a great way to improve the function and cleanliness of floor spaces in areas like these and in many cases is a requirement by the facility we are working in. We approach this type of work with not only an eye on the age of the slab and RH readings but we also try to get an understanding of the processes over time that have contaminated the slab. We have seen airborne misted oil, improper chemical removal of asbestos that contaminates concrete in commercial areas, cutting fluids, and even silicone as contaminants. When you combine certain contaminants with high RH the risk of a failure in the epoxy vapor barrier application is very high.
Steps to Reduce the Risk: If you read the technical data sheets for reputable vapor barrier manufacturers they will spell out what is required for warranty. Basically it is proper concrete surface profile on clean, dust free, hard concrete without contaminants.
Our first step in assessing the risk is to ask the customer what are the processes and materials that contaminate the slab. Once we have a feel for the history and what may be in the slab we try to determine if we can accept the risk. Many times we have of core sampled the concrete using an outside lab testing firm to look at what contamination is so we know what level of surface prep is required. Other steps always include some type of surface prep usually shot blasting and when contamination is known we will try different forms of cleaning to remediate the contamination. For example if we know its oil we will use microbial enzymes for treating oily floors. Once this step is complete and the floor is dry we will proceed with epoxy vapor barrier. Most of the time we are finishing the moisture remediation with a finished epoxy floor, urethane, or chemical resistant floor coating that meets the customer’s needs.
Informing the customer in our proposal that contaminated floors have risk of bond failure especially in older slabs with moisture problems. That risk is not one the our company takes on, we always disclaim responsibility for bond failure if contamination is confirmed. Most of the time we are able to proceed with projects with an understanding that our best efforts for surface prep and addressing contamination the best it can be. But other times we have lost or turned away contracts or work that present too much risk to Industrial Safety Coatings or the customer.
In any event if slab contamination is addressed properly the odds of a successful epoxy vapor barrier are pretty high. The key for us has been to get agreement and an understanding of risk before proceeding.