Innovations in Flooring

Advances in flooring can sometimes happen right under your feet

By Peter J. Arsenault, FAIA, NCARB, LEED AP

Flooring is one of the most used and most noticeable features of any building interior. Its aesthetic impact is related to both its initial material makeup and the ability of that material to hold up over time with continual use. The presence of not only people walking in all types and manner of shoes but also the things they carry in on those shoes, such as dirt, snow, water, and other contaminants, can wear down the finish of the floor. The use of heavy-duty cleaners and polishes to overcome that issue is the usual response, but some of those can be equally as harsh and damaging to flooring. Further, many floors in commercial buildings need to withstand rolling carts, suitcases, or even small motorized vehicles, all of which add their own stress on the floor system. Beyond all of this, the ubiquitous nature of flooring means that the materials used either in the flooring product itself or the materials needed to install it, such as adhesives or cements, can have a significant impact on the indoor environmental quality of buildings. Hence, it is often the focus of green building design attention.

In response to the need to not only look good in a variety of colors, styles, and patterns but also to hold up to the usage and environmental demands of commercial buildings, flooring product manufacturers have worked hard to develop and improve their offerings to design professionals. In this course, we will look first at some considerations for the structure that a flooring system rests on and then some of the innovations and options currently available. By understanding flooring choices as well as the characteristics and properties related to those choices, architects and others can design and specify flooring systems that hold up and perform well, contribute to better indoor environments for people, and look great.

Floor Structure

Before delving into particular finish flooring choices, it is important to consider that the structural system of a commercial floor is a critical component of any flooring. As the structural substrate to the flooring, its attributes interact with the flooring in ways that either create favorable conditions for the finish flooring to function or, alternatively, can cause problems. In fact, most finish flooring problems come about not because of problems with the finish material but because of problems with the material or structure underneath it. As such, the attributes of the structural floor system can directly affect the real or perceived attributes of the finish flooring, regardless of what is selected.

Structural floor systems commonly involve steel and concrete, although there are plenty of variations in how they are designed. Traditional, lightweight systems use steel girders, beams, or trusses to support a metal floor deck that is topped with concrete. That can create some deep systems that require a tall floor-to-floor height. Precast concrete or poured-in-place concrete structural floors can be thinner, but those systems need to be assessed for the amount of additional dead weight they create compared to other attributes that may or may not offset the cost of the added weight. With an understanding of the benefits and drawbacks of different traditional systems, it is not surprising that an innovative alternative is becoming popular in the form of long-span composite floor systems that combine the versatility and ease of erection of steel with the strength and durability of concrete. Referred to as a long-span composite floor system, it achieves a thin-slab advantage characterized by a narrow floor structure, longer unobstructed floor spans, and a range of under-floor aesthetic ceiling options. So while these systems address the economy of the structure, they also address the economy of room spaces with an eye on ceiling design, including the efficient integration of acoustical treatments, controlled sound attenuation, and fire resistance.

Long-span composite floors function by using the best of each material in this hybrid or composite system: the tensile strength of a corrugated metal deck and the compressive strength of reinforced concrete. Together, this system allows for longer spans that can eliminate the need for intermediate supports and create a single floor/ceiling assembly that allows more economical floor-to-floor heights. Two common types are as follows:

• Dovetail composite deck profiles: This typical profile is capable of supporting clear spans up to 28 feet. Its name comes from the dovetail-shaped profile of the corrugated metal panel that receives the concrete and bonds firmly with it. This can provide extra rigidity and strength that allows finish flooring to function properly without fear of deflection or movement. This profile can be particularly useful in midrise or multistory residential projects, such as hotels, health-care communities, and dormitories where walls between units can support the floor deck without the need for intermediate supports.
  
  
• Deep deck composite profiles: Deep deck composite floors support even longer, wider, and more open spaces than dovetail profiles. Clear spans up to 36 feet are commonly achievable, meaning they are well suited for buildings where open space and free-flowing interiors are sought.

Since the nature of the composite metal deck profiles can vary notably between suppliers, and so can the structural capabilities, it is advisable to work early on with the technical support staff of the manufacturers. Some of them engineer and offer a complete range of steel building systems, both traditional and new, so they can provide information for architects and engineers to select the best system appropriate to a particular project. That can help a building not only excel in the area of design intent but also holistically take into account related factors, such as material costs, erection costs, performance capabilities, and project timelines. For example, long-span composite floor systems can be engineered to address unique loads that may be imposed by a particular use, such as equipment placed in the building or curtain wall systems that impose loading on the floor edge. Those conditions may cause unwanted vibrations or deflections in the floor. Working collaboratively, the design team and the manufacturing team can determine the best floor system to address those issues with the proper rigidity and load transfer design. That design also helps to assure that whatever finish flooring is placed on top of the concrete, it will not be subject to undue movement, which can cause degradation and failure of the flooring.

Common Flooring Choices

The possible choices in finish flooring are extensive. Selection can be based purely on aesthetic considerations, performance concerns, green building requirements, or some combination of any or all of the above. With that in mind, let’s look at some of the innovative choices currently available.

Tile and Stone

The use of tile and stone for flooring is centuries old, and the available choices reflect that history. The properties and attributes of each of these materials are well-known, and the range of colors, textures, and patterns is impressive. One of the recent innovations here is the use of large-format porcelain tile (officially known as gauged porcelain tile/panels/slabs) made possible by modern manufacturing equipment and processes that can consistently produce quality products. Directly related to this innovation has been the need for new lightweight mortars designed specifically for large tile installations. Accordingly, manufacturers of adhesive mortars (i.e., different from producers of tile and stone) have developed specific formulations designed for large, gauged porcelain tile/panels and large-format tile and stones, for both floors and walls. Such mortars can prevent slippage of the large tile once it is in place, while providing exceptional bond strength over the full area of the tile.

Whether large format or not, all tile and stone work is dependent on the quality and makeup of the mortar, grout, and other products that are necessary for a successful installation. Identifying a manufacturer that offers a comprehensive line of high-performance flooring installation products is important to meet the needs of flooring, whether for interior or exterior applications for commercial or residential buildings. Some offer a significant warranty to cover a professional installation based on following manufacturers’ guidelines and recommendations. Many such mortars and grouts are proven around the world in virtually every climate and application where tile and stone are used. Their ease of use, strength, and durability help architects bring designs to life knowing that they will perform well over time.

Resinous Flooring

Resinous flooring is essentially a durable coating over concrete that offers many benefits to owners and specifiers. There are several types, including epoxies, acrylics, and urethanes, but one of the more innovative options is referred to as a polyaspartic concrete coating. Polyaspartics are seamless, high-performance polymer coatings designed for protection that are often viewed as a variation or type of polyurea coating. They were first developed in the early 1990s as a protective coating for steel bridges subject to harsh outdoor environments. Today, polyaspartic coatings are widely used in protective resinous concrete floor coating applications, both interior and exterior. Generally, any type of environment where a resinous concrete floor coating is called for, a polyaspartic coating system may be used. This includes heavy-traffic industrial and commercial flooring as well as residential garage floor coatings.

One of the primary benefits to polyaspartic coatings is the versatility of the material. Common coating systems can be selected from standard solid colors for industrial floors, but seamless flake and monolithic quartz flooring systems are also common. Recently, new decorative floor coating applications, such as dye and seal and metallic floor coating systems, have been developed. From a performance standpoint, based on empirical testing data, polyaspartic coatings offer abrasion-resistant capabilities that exceed those of typical epoxy systems. During installation, polyaspartic coatings may be applied with a squeegee, seal-coat broom, or even a simple nap roller and will dry in a matter of hours, allowing use of the floor the next day. And, depending on the formulation, polyaspartics may be applied in extremely low temperatures below 32 degrees Fahrenheit (0 degrees Centigrade).

All resinous floorings, such as polyaspartics, provide significant benefits to a building project. The first is the ability to be a visually attractive, decorative concrete option that can be customized in appearance and finish. At the same time, it is a very durable choice that can be formulated for dramatic wearability and resistance to harsh conditions. This includes formulations that are resistant to chemicals that can cause stain or other damage that may be present in a facility. Of course, it is important to remember that a floor coating is only as good as its adhesion to concrete. Typically within the industry, concrete floor coating adhesion is measured with a pull test that provides a PSI reading, with concrete fracturing at 400 PSI of pull force. Coatings at or above this reading are recognized as having optimal substrate adhesion. From a user perspective, resinous floorings can achieve slip-resistance factors that are consistent with The Americans with Disability Act or other accessibility standards. Finally, related to floor maintenance, investing in a proper concrete floor coating can make floors easier to clean, which is particularly beneficial for high-traffic areas. Such maintenance can be enhanced when resinous coatings are applied up the base of a wall, allowing for a cove or seamless transition between the wall and the floor, thus eliminating joints or seams where dirt and bacteria can thrive.

Resilient Flooring

Resilient flooring includes a range of materials that are characterized by their ability to take some pressure or force and “bounce back” from that force to look as good as new. These include things like vinyl composition tile (VCT), vinyl sheet goods, PVC flooring, or rubber products. Sometimes overlooked in this category is linoleum, which was first invented in 1860 and has always been considered to be an excellent, inexpensive material for high-use areas. It has enjoyed a resurgence in use lately because of its use of all natural and mostly bio-based ingredients, making it a very sustainable choice. These ingredients include rosin tapped from pine trees, linseed oil obtained by pressing the seeds of the flax plant, wood flour made from timber grown in controlled forests, cork flour made by grinding the bark of the cork oak, and limestone found all over the world in enormous quantities. Added to this combination, ecologically responsible pigments are selected to create a wide range of attractive colors, while backing material, including webbing for the linoleum, can be made from natural jute grown as a renewable material.

Linoleum-finished products using these natural ingredients commonly include sheet, tile, and specialty floor coverings that are very well suited to the needs and demands of a healthier, safer indoor environment. That is in part because it is easier to clean and care for than other resilient flooring alternatives. But another important characteristic is its ability to provide natural antimicrobial functions without using any pesticides or biocides. Linoleum is made of natural ingredients that resist microbial growth by their very nature.

There are some practical benefits from installing linoleum as well. The nature of the product is that pieces seal tightly together, meaning that seam welding is not required, thus saving time and cost in installation. Linoleum also outperforms vinyl and rubber in dimensional stability, hygienic protection (when properly installed with net fit seams), and resistance to topical moisture. Linoleum is occupancy ready at installation and half as expensive to maintain, freeing maintenance staff to focus on other work. In terms of durability, the 25- to 40-year service life of linoleum far outperforms vinyl or rubber.

Entrance Flooring

Too often, one of the most overlooked and underappreciated products within a building is an entrance flooring system, which is an engineered mat or grid flooring system designed to trap dirt and debris at the door. They’re usually the last products to get installed, and one of the first products to get value-engineered off the project. However, they are one of the most functional and cost-saving products that can be included in a building relative to their overall cost. That is because entrance flooring stops dirt at the door, thereby reducing the damage it can do when tracked over other flooring systems and greatly reducing maintenance costs. It also improves indoor air quality by reducing airborne particles and the need for harsh cleaning chemicals. Since it can trap rainwater too, dangerous conditions like slippery floors can be reduced, thus helping to eliminate slip-and-fall accidents. There is a wide range of entrance flooring products available, so selections can be made to suit different building types, usage, and budgets, all while contributing to a positive first impression at doorways and entrances.

Permanent entrance flooring systems have been manufactured and incorporated into buildings since the 1960s, so they have proven themselves repeatedly over time. Products include systems that are made from aluminum or stainless steel with common choices of computer-milled, modular mats, and grids. There are options for both surface-mounted systems that sit above a concrete floor and recess-mounted applications that require that the concrete slab be formed to accept it. Most manufacturers will provide technical assistance during the design phase to assure proper sizing coordination, product samples, and other details. Through this collaboration, products can be selected that are best suited to different building types and design factors, such as weather, foot traffic, rolling loads, and ADA compliance. It allows architects and designers to gain insights into addressing the complexities of proper space layout and product choices for different applications. It also helps determine which aesthetic options and materials will best suit the overall design intent to either blend with the surrounding flooring or provide a visual accent. Once the project moves from design into construction, the manufacturing team can assist with field-verified dimensions, onsite technical support, product mockups, and sample coordination.

The value of entrance flooring systems is most fully realized by the building owners and maintenance staff. If these systems are not included, then many owners resort to hiring a laundry service to bring in portable, roll-out floor mats that need to be washed and replaced routinely depending on the conditions. That solution simply traps as much water and dirt as the mats will hold, often creating saturated, overloaded conditions that overflow onto the rest of the flooring. The cost of this ongoing maintenance can quickly exceed the cost of installing a proper entrance mat system in the first place. Wade Brown, senior product marketing manager of Construction Specialties, notes, “If entrance flooring systems are not designed and included at the time of construction, it becomes the owner’s problem to solve how to best keep dirt and water from entering through their front door, and ultimately protect all the building’s occupants from hazards, such as slips/falls and poor indoor air quality. The architect’s decision on what products to use, or whether to use them, can have a lasting effect on those who inhabit the building over its life time.” Overall, by stopping dirt at the entrance, the rest of the building thrives. Since entrance flooring systems are known for their durability with systems that stand up to years of foot traffic, heavy equipment, harsh weather conditions, and tracked-in debris, it is easy to see why they have very favorable payback periods.

Green Building and Acoustic Considerations

With a good overview of some of the types of flooring systems and design issues that need to be addressed, let’s turn our attention to some performance issues specifically related to sustainability. When looking at the systems already discussed, here are some things to be aware of in terms of how they can contribute to green building certifications and environmentally conscious decision making in general.

• Composite floor systems: Long-span composite floor systems align well with green building programs such as the U.S. Green Building Council LEED v4 rating system. That’s because they support a holistic, long-term view of project performance and costs, both to the building owner and to the environment. The longer a building can remain in service, the fewer resources that are needed to construct a replacement. This applies not only to the building structure but also to interior changes. Long-span composite floor systems afford large open spaces that make it easy for internal tenant moves, additions to tenant space, or other configuration changes without requiring extensive demolition and disposal.
  
  
• Tile and stone mortar products: The best way to be sure that mortar and related products help with positive indoor air quality is to request product-specific environmental product declarations (EPDs) for mortars, grouts, and similar products used as part of a tile or stone floor. In addition, health product declarations (HPDs) can be requested to document that products are free of toxic chemicals. Either of these documents can help a project achieve LEED certification, however, not all manufacturers can provide the needed information. Therefore, if certification is important, then it is worth seeking out manufacturers that have taken the initiative to be transparent in their product formulations and can demonstrate their commitment to the environment through the use of safe ingredients and compounds. Mortars, including thin-set mortars, can be independently tested and verified by independent agencies for low levels of VOCs and other specific compounds. For example, Underwriters Laboratories Environment (ULE) is the exclusive provider of GREENGUARD Certification for products that meet stringent chemical emissions requirements and have tested and certified some mortars. As Mitch Hawkins, technical services manager of LATICRETE, points out, “The goal is to provide maximum disclosure so as to allow the design team and building owners a better opportunity to make more informed decisions when it comes to choosing what products will go into their projects.”
  
  
• Resilient flooring: As noted earlier, linoleum is the only resilient flooring material that is 100 percent bio-based from natural materials and is biodegradable. Based on this, independent life-cycle assessments (LCA) have been performed that prove that linoleum is far less harmful to the environment than vinyl and rubber. Thanks to a formulation that is free of the environmental toxins emitted by vinyl and rubber flooring, linoleum minimizes threats to current human health and the genetic wellbeing of future generations.
  
  
• Entrance flooring: An important purpose of entrance flooring is to improve indoor environmental quality. It is an integral part of a green building design because it removes and traps a bulk of the dirt and moisture from pedestrians’ shoes before they travel farther into the building. This keeps contaminants out of the building and is recognized as such in most green building certification programs. From a long-term durability standpoint, entrance flooring helps to extend the life of the interior floors and decrease maintenance needs. By requiring less chemical based floor cleaners, they help improve indoor air quality during building operations and maintenance.

Acoustics

Acoustics is increasingly recognized as a significant factor in green building standards and deserves some specific attention here. Most people think of acoustics in terms of walls or ceilings, but the reality is that floors, particularly in multistory buildings, have a role to play in good acoustics too. Several important distinctions need to be made since there seems to be a fair bit of confusion on sound and acoustic properties of flooring materials:

• Sound movement: When sound radiates through the air and strikes a material, some of that sound energy is absorbed, some is reflected, and some is transmitted through the material. How much sound follows each of those three paths is a function of the acoustic nature of the material it strikes. Individual materials can be formally tested according to ASTM C423 to measure the sound-absorption rate on a scale of zero to one. Hence a material with a noise reduction coefficient (NRC) of 0.0 can be presumed to reflect back all of the sound striking it (i.e., not absorb any), while a material with an NRC of 1.0 is represented to absorb or transfer all of the sound that strikes it. The NRC is useful for determining the sound-absorbing characteristics of materials in many general building applications and may be used for some flooring materials.
  
  
• Airborne sound transfer: Airborne sound that is not absorbed or reflected from a material is transferred through it to the other side. Hearing loud music or speech coming from an adjacent room is an example of airborne sound passing or being transferred through a wall. The same thing can happen in floors—the airborne sound can pass through a floor/ceiling assembly to the room above or below. How much sound transfers through an assembly is determined by the sound transmission class (STC) according to ASTM test methods. A higher STC rating (50 to 60 or above) means that more sound is blocked, while a lower STC rating (35 or less) means that more sound is transmitted through. The important thing to remember about STC ratings is that they are necessarily based on the entire floor/ceiling construction assembly, not just a single material. That means that the floor structure, any underlayments, any ceiling materials, and sound-deadening materials are as important as the floor material itself. Dense materials like steel and concrete are good at reflecting airborne sound, thus allowing very little to pass through resulting in higher STC ratings. Similarly, softer materials such as carpet or some resilient flooring are good at absorbing airborne sound, also producing higher STC results. Assemblies without enough reflection or absorption will transfer more sound through them.
  
  
• Structure-borne sound transfer: Sound can be created or emanate within a building structure or assembly, radiating outward from the structure into the air and to the ears of anyone nearby. In floors, this can happen when someone walks along an upper floor in hard-soled shoes or drops an object onto the floor. In this case, the separate impact insulation class (IIC) is used as a measure of the ability of a floor/ceiling assembly to absorb or deflect sound from such impacts and keep it from being transmitted to the space below. The IIC is only a measure of such structure-borne sound and not of airborne sound. In this case, hard surfaces, such as concrete or hardwood flooring, are a detriment since they will transfer impact sound quite readily. Resilient and carpet flooring can soften impacts and thus produce more favorable IIC ratings.

The first step in controlling sound transfer through floors, then, is to understand the nature of the sound transfer as summarized above and how to design a floor/ceiling assembly to control it. In most cases, both airborne and structure-borne sound will need to be addressed for successful acoustical performance. The structure and any penetrations needs to be looked at in terms of acoustics, and then the rest of the assembly can be considered. In some cases, it will make sense to install an added underlayment layer that can isolate the finish flooring from the structure and improve the IIC, although it may have some limited effect on STC ratings too.

The choice of finish flooring will make a difference in the sound transfer but also the sound qualities within a space. Since hard surfaces, such as concrete and tile, are good at reflecting sound, they may create echoes within the space that can make it difficult to discern speech or just create a higher level of background noise unless other acoustic measures are undertaken. Softer surfaces, such as resilient flooring, can absorb more sound and help reduce the degree of echoes or noise in a space. Overall, it is the acoustical comfort of the people using the facility that is sought to produce a healthier, more enjoyable indoor environment that is conducive to a variety of activities.

Conclusion

Flooring is a significant interior design feature of a building. It provides a far-reaching aesthetic as part of an overall design concept. It needs to perform to hold up over time with an appropriate amount of maintenance. It can add or detract from indoor environmental quality and health concerns. Design professionals who acknowledge the options and understand the differences can achieve success in all three of these areas.

Peter J. Arsenault, FAIA, NCARB, LEED AP, is a practicing architect, green building consultant, continuing education presenter, and prolific author engaged nationwide in advancing building performance through better design. www.linkedin.com/in/pjaarch