Bill Mabeus, vice president of sales for Fishman Flooring Solutions, has been involved in evaluating and preparing thousands of slabs for flooring installations during his more than 30 years in the flooring industry. He recently shared with Floor Trends his unique perspectives on why the proper preparation of surfaces is so important to architects, designers, specifiers, building owners and end users. He also discussed some of the issues with slabs that need to be addressed to ensure a successful flooring installation.

How would you assess the importance of properly preparing slabs for flooring installations?

Mabeus: Proper slab preparation is one of the most important factors in successfully installing a floor. Taking shortcuts in the process can result in flooring failures, unsightly show-through of slab imperfections, a shortened flooring life and even loss of warranty, all of which will result in end users who are not satisfied. Regardless of the type of flooring to be installed, proper installation always begins with proper slab prep.

Could you put a price tag on the annual costs to building owners, contractors and others when uninformed decisions are made about slab preparation?

Mabeus: I can’t quote a specific number, but the price tag is astronomical. Moisture failures alone are costing building owners tens of millions of dollars per year. That’s why testing for moisture is now a standard requirement at most commercial flooring companies.

What is the single most important factor in prepping a slab for a new floor?

Mabeus: Good communication is the key, so that everyone involved understands the scope of work. That means the general contractor walks the job site with the flooring contractor’s project manager or installer before the job starts in order to assess the condition of the slab surface and determine what’s necessary to properly prepare it. When old flooring is involved, the scope of work generally includes removing adhesives and minor floor prep, such as patching control joints on the slab. On new slabs, the scope of work may include sanding to clean off drywall mud and paint overspray. Minor prep never includes addressing slab imperfections.

What is the most common problem you see with slabs that needs to be addressed?

Mabeus: The most common problem today is high relative humidity in the slab. New slabs are often treated with curing compounds and then power-troweled to a tight finish that keeps the moisture in the slab to help cure the concrete. To save costs, general contractors will often avoid turning on the HVAC in the building as long as possible, which results in the moisture not being pulled out of the slab. As a result, the relative humidity in the slab is often too high to install the flooring when the flooring contractor arrives to begin work.

What are the implications of too much moisture in slabs and how can moisture problems best be remediated?

Mabeus: Flooring installed on a slab with high moisture will most likely fail. The failure may be as simple as the floor releasing from the slab. It could be water re-emulsifying the old adhesive, which is pushed through the seams in the flooring and can be tracked throughout the building. Or it could be gapping and peaking in resilient tile or mold and mildew forming in areas.

High moisture in a slab may delay the installation until it can be addressed. In order to move the installation along, it’s not uncommon for a general contractor to offer to sign a document stating the flooring contractor or installer will not be held responsible for flooring failures due to high moisture. I’d never advise the flooring contractor or installer to accept such an agreement.

The best systems to deal with moisture problems involve shot blasting or grinding the slab to a recommended concrete surface profile (which varies by product), applying a two-part epoxy moisture system and then priming and leveling or patching, depending on the flooring requirements. There are several sheet membranes that are proven to work as moisture barriers as well, when they’re used within the recommended parameters and installed properly.

What advice do you have for removing old adhesives?

Mabeus: The first step is to verify that the old adhesive doesn’t contain asbestos. Once that’s determined, the most common way to remove the old adhesives is with a scarifying disc with carbide bits attached to a sander or proper buffing machine. I say proper buffing machine because most common floor buffers that are used for waxing are not sufficient to remove adhesives.

So many of the new flooring backings today contain recycled content, which may not be the same from manufacturer to manufacturer. As a result, it’s critical to use proper techniques to remove the old adhesive, which may not be compatible with the recycled backings, and follow proper guidelines and the manufacturer’s instructions for installing floors.

Given its implications for human health, addressing a flooring slab with asbestos requires extreme care. How should asbestos be removed?

Mabeus: Asbestos removal is beyond the scope of work for most flooring contractors. There are strict guidelines and requirements for removing and disposing of asbestos. The work should always be done by a licensed asbestos removal company.

Asbestos adhesive is considered a contaminant on the slab and is typically removed with chemicals that ultimately soak into the slab. Good communication between the general contractor and the abatement company is important to ensure that the old chemicals are removed properly. If communication is lacking, the slab that has been chemically abated needs to be prepared properly to isolate these chemicals. Failure to remove or isolate them almost always results in a floor failure.

What are the problems that can surface when curing compounds and moisture mitigation products are mixed with concrete? How prevalent is this practice?

Mabeus: There’s been a trend in recent years to add moisture mitigation products to the concrete mixture. These products are often specified by architects or building owners. Some of them require that the slab is burnished so tightly it creates a very high surface gloss, which is completely non-porous. This makes it nearly impossible to stick resilient floor to the slab.

Many of the resilient manufacturers require a minimum of one-eighth inch porous material to adhere their products to the slab. This may require grinding the surface and patching it to properly install the floor, which may void the manufacturer’s warranty of the moisture mitigation product.

How has the technology to enable better surface preparation evolved over the past five to 10 years? Are there new and better products on the market?

Mabeus: There are many new specialty problem-solving patches and levelers on the market that are designed to address the toughest problems. These include levelers that can go over old adhesive and even carpet and floor patch that resists high moisture. There have also been many improvements in tools, including buffing machines and grinders, which are designed to remove old adhesives and coatings.

Where can building owners, contractors and flooring installers go for answers to their questions about proper surface preparation?

Mabeus: An excellent source of information is local floor covering supplies distributors. They have detailed knowledge regarding a range of products designed to avoid or address any problem involved in properly preparing a slab. Also, distributors can easily tap into the resources of many adhesive, patch, moisture mitigation and tool companies for solutions to particularly tough problems.