Surface prep is one of—if not the most—important aspects of any flooring project. Substrates serve as the structural and foundational support for a vast array of flooring types and are crucial to the proper wear and stability of the surface. But when construction timelines shrink and installation budgets come under intensifying scrutiny, this crucial step can be a hard sell to building owners and developers. Plus, proper surface prep is often ignored or mishandled by inexperienced, untrained floorcovering installers. 

Considering a floor is only as good as the substrate beneath it, these situations can translate into major problems down the road. Complications range from subfloor telegraphing to moisture problems to total flooring failure. The “worst-case scenario,” total flooring failure, can lead to enormous financial and logistical headaches for you and your client. It can also result in a major loss in revenue for commercial building owners while flooring and substrates are removed and re-installed. 

In order to avoid these costly mistakes, proper training and certification are key. It’s also important to learn from industry professionals who are implementing successful best practices in the field. Whether it’s effective moisture testing, incorporating advanced new products or working alongside concrete contractors to ensure the right make-up and finish, there are a number of tips and tricks that improve the surface prep process and eliminate flooring failure. 

Crucial Steps for Reducing the Threat of Flooring Failure 

Before beginning any installation, installers should thoroughly prepare the substrate to confirm the surface area is properly cleaned, level, dry and structurally sound. This step is crucial to ensuring the finished flooring performance will not be compromised and require a complete reinstallation or costly repairs. 

There are also specific considerations when choosing a substrate as this building material’s primary role is to provide optimal adherence to the desired floor covering. Although there are many types of substrates, plywood and concrete slabs are the most commonly used because of their strength and durability.

Plywood substrates are made by layering fabricated sheets of wood veneer that are bonded together with special adhesives under heat and pressure, and cross-laminated. This technique ensures the substrate is not susceptible to the expansion and contraction that hardwood is known for. 

When using plywood, installers are recommended to apply a subfloor adhesive to the top of the floor joists to prevent the plywood from moving around and squeaking. Lastly, the appropriate type and thickness of the required underlayment depends on the specified flooring finish.

With concrete substrates, the existing floor surface can often be removed without complete damage to the concrete when remodeling is in progress. This is one of the most appealing aspects when working with this material. But since concrete slabs are typically 4” to 6” thick, they take months to fully dry out. Before proceeding with finished flooring installations, installers will need to test the slabs to ensure the substrate is in good condition.

A number of new products have hit the market that are more accurate and easier to use than ever before. These include in-situ probe testing units that can provide an instantaneous moisture reading. For each probe or sensor, a hole is drilled measuring 3/4” in diameter and at a depth equaling 40% of the slab’s thickness for slabs that are drying from one side or at 20% depth for a slab drying from two sides. The probes can also be left in place for weeks at a time to see if there is a change in moisture levels.

It is also important for installers to consult floor covering manufacturers since surface preparation requirements and methods vary depending on the type of substrate. For example, when applying floor finishes over concrete substrates, some floor coverings require a light grind or shot blast to a specific concrete surface profile while others require a more aggressive mechanical surface preparation in order to achieve a tenacious bond. Slab moisture conditions such as relative humidity (RH), moisture vapor emission rates (MVER) and the level of alkalinity (pH), must also be taken into consideration.

Thankfully, moisture is less of a concern for contractors working on retrofit or remodel projects. We always check for slab moisture, however, in retrofit and remodels moisture is generally only a concern in ground floors and below.” explained Steve Poniatowski, Vice President of Sales, INSTALL Warrant Contractor Resource New Jersey Commercial Flooring. “Renovations come with other challenges such as old adhesives, patch subfloor irregularities which often require profiling and patching to make smooth and flat.

“What we do have to worry about is the increase in power troweling in new construction,” he interjected. Concrete contractors often use power trowels to create a smooth finish on newly poured floors. The trowel’s large blades can burnish the floor and turn the surface of the concrete into a non-porous layer. While this provides required flatness for the general contractor it is also similar to  polished concrete with slab being non-porous. There are no open cells for moisture to escape and the result is a slab that takes longer to cure and makes it nearly impossible for flooring material to bond. 

To remedy this, flooring contractors lightly grind or shot blast the surface. However, in a world of fast-paced construction this is a time-consuming process that can put them behind schedule. “Even when you shot blast the surface, the slab can still have a high level of moisture,” added Poniatowski. “We end up recommending a moisture mitigation system and use a self-leveler to correct any moisture and slab imperfections. This puts us further behind but is necessary to ensure the integrity of the installation.”

When using self-leveling products, installers also have to address moving joints and cracks present in the substrate to avoid the transference of cracks in the finish. It’s recommended that installers evaluate and isolate the area around walls, columns, penetrations and other building elements where movement may be anticipated to allow for natural building movement against retraining surfaces.

Changes in the Industry and Areas for Opportunity 

Poniatowski has spent nearly two decades building the company’s presence in New Jersey, New York City and Philadelphia. During his tenure, he has initiated a number of best practices that helps Resource Commercial Flooring stand out from its competitors. 

“We pride ourselves on the training and education level of our installers and our project managers” explained Poniatowski. “Thanks to this expertise, installers are able to identify potential problems on the jobsite. This includes contaminants in the substrate, such as mastics, curing compounds and oil which can affect the finished flooring system.”

His team is also well versed in advanced products that reduce flooring failure as well as turnaround times for occupied buildings. This includes spray adhesives with high moisture resistance, self-levelers and other underlayment products.

With the inclusion of a self-leveling underlayment or waterproofing membranes, the finished flooring system has added protection from water intrusion and cracking. Additionally, underlayment products can aid in noise reduction and help to present a better overall surface to adhere finished flooring – leading to longer-lasting installations and happier building owners.

Another best practice Poniatowski introduced comes in the form of relationship management. Resource Commercial Flooring started work on a 63-story apartment tower. Long before any flooring was installed, Poniatowski got in touch with the concrete contractor to fine tune the power troweling process. 

“We wanted to know what kind of finish we would be working with” said Poniatowksi. “If it was perfectly smooth then we would need to shot blast all 63 floors at an enormous cost to the building owners. However, if it was wavy or full of irregularities, we would have the opposite problem, and need to self-level” he added.

After several test runs, they agreed that three passes with power trowel would provide a flat floor that was rough enough to be porous and bondable “We ended up spray painting this section of concrete with an approval date and it became the standard for the rest of the building,” he said. “Doing this in other major projects will save us time, money and headaches – along with time and money for building owners and developers.”

A Revamped Effort to Improve Substrate Preparation

In spite of progress there is still the need for better awareness and aptitude of proper substrate preparation and installation. That’s why INSTALL is evolving its groundbreaking Surface Prep Certification to meet new challenges and demands. 

First introduced in 2016, the certification process is a collaborative effort between INSTALL educators, contractors, installers and industry manufacturers. It combines intensive substrate training curriculum with written and hands-on evaluation. This process starts with classroom hours and an extensive written exam, followed by the certification evaluation in the form of a hands-on application and installation of underlayment material. 

Today, INSTALL has expanded its industry partnerships for the program to 10 substrate and underlayment manufacturers and is hard at work revising curriculum to meet new challenges in commercial construction.

See more floor installation best practices and industry updates

“Surface prep remains an exciting opportunity for INSTALL and the UBC,” said Mark Olsen, INSTALL instructor and member of the North Central States Regional Council of Carpenters. “We are on the forefront of training that addresses new technology, products and installation techniques, and will continue to lead the industry in terms of certification and best practices.”