By: John Hoover

Content: surface preparation / underlayment

The successful installation of any flooring rests with properly preparing the substrate and correctly using the appropriate floor prep products to remediate any problems with it. The stakes are high because failed flooring installations cost retailers, specifiers, installers and others more than $500 million annually, according to some industry analysts. 

FCI recently turned to flooring industry veteran John Hoover for his thoughts on substrate preparation and today’s floor prep technologies. Hoover is a business manager in Virginia for Fishman Flooring Solutions and has assisted in the preparation of more than 1,000 substrates. 

FT: What’s the most important thing retailers, specifiers and others need to know about prepping substrates and the use of floor prep products?

Hoover: Without a doubt, a successful flooring installation begins with selecting the right flooring installation contractor. A top-notch installer, who has experience prepping substrates, can go a long way to avoiding costly immediate and long-term problems. 

The best flooring installers are knowledgeable about the latest floor prep technologies. An installer who understands the range of products on the market can save everyone time and money, which is important in today’s fast-track construction environment. 

Most distributors of flooring and flooring installation products are good sources for finding the most qualified flooring installers for a given job.

FT: Moisture in substrates seems to be today’s poster child for failed flooring installations. Why is that?

Hoover: Moisture is a significant issue because much of today’s flooring is less forgiving with respect to moisture than products of the past, as are many adhesives currently on the market. As a result, most flooring and adhesive manufacturers require stringent pre-installation moisture testing, not only on the surface, but also 40 percent down into the depth of the slab. For example, with a six-inch slab, the moisture testing probes should be set at a depth of 2.5 inches. Tolerance to moisture differs from one flooring product to another, so documenting test results and sharing them with manufacturers is essential. 

With older slabs, moisture barriers are commonly compromised or there is no moisture barrier at all. These issues need to be addressed to avoid a moisture-related installation failure.

FT: You mentioned today’s fast-track construction environment. Does that play into failed flooring installations?

Hoover: I think fast-track construction can certainly be a contributing factor when flooring installations fail. Let me give you an example. Many concrete slabs today have a curing compound that is topically applied to the surface of the slab when the concrete is poured. These compounds are designed to accelerate curing, but are potential bond breakers if not properly removed, often by sanding, before the flooring is installed. 

Also, prepping a slab properly can be very challenging. So, cutting corners to meet tight deadlines can lead to costly problems over the long term.

FT: Let’s shift to floor prep products. Is there a key to successfully using them?

Hoover: That’s a very simple question to answer. For any floor prep product to perform as advertised, you need a clean, structurally sound, properly prepared surface with no bond breakers. That’s true for both new and old slabs. 

The quickest way to see if a slab is clean is to put a piece of duct tape on it and then peel it off. If it peels off easily or there is dirt on the tape’s adhesive, it’s a signal that the slab has not been properly cleaned. 

FT: Are there one or two common mistakes regarding the use of floor prep products that you see in the marketplace? 

Hoover: It’s all about bond breakers, which I commonly see on substrates. For example, removing old adhesives is necessary because newer floor prep products are potentially incompatible with them. This is particularly true with today’s latex-based adhesives that often do not bond with older solvent-based glues.

FT: Do floor prep products differ by the type of flooring to be installed?

Hoover: Yes. Wood, ceramic and carpet can usually be installed over Portland base patch. The outlier is vinyl, especially heat-welded vinyl. Vinyl needs a smoother finish that won’t telegraph through the installed flooring. This is where smooth finish patching compounds are typically used.

FT: Is there a rule of thumb regarding thickness when using a floor prep product? Does the thickness matter?

Hoover: Most adhesive manufacturers require a minimum of one-eighth inch thickness for porosity and to give the adhesives a chance to work properly. Thickness becomes an issue if a substrate needs a deep fill or tapers off to nothing. Fortunately, there are products that address these situations ranging from skim coats to those that can be built up several inches. 

FT: How have floor prep technologies evolved over time? What are some new technologies that have caught your eye?

Hoover: There are floor prep products now available to meet every possible marketplace need. They range from products that are applied by hand to those mixed in a machine and poured on the floor and smoothed. I’m impressed with new patch technologies that can withstand a much higher level of moisture than older products. Some of them can even be applied prior to a moisture mitigating product.

Also, new moisture testing technology was recently introduced that consolidates many concrete moisture testing tasks and simplifies the moisture testing process. The same system is also capable of storing more than 500 time-stamped measurements, so it’s possible to recover historical data years after the original moisture testing took place. That information can be very valuable to retailers, specifiers, installers and others in today’s litigious society.