Why Concrete Contractors Need Certification for Big Box Store Jobs


In 1962, retailers began building large suburban stores surrounded by parking lots, and the “big box” store was born. Since then, supercenters and megastores have continued to find success in the retail environment. Besides their eponymous tall and boxy design, big box stores have several identifying characteristics: they are typically single-story structures with warehouse-style construction, have few interior columns (thus maximizing floor space), and have a concrete slab foundation.

One of the largest online retailershas added a requirement for ACI commercial/industrial flat finishers on each project.

Concrete slabs are often 100,000 square feet or more and require sophisticated construction methods compared to conventional floors. Floor flatness is a critical consideration, as floors need to accommodate ultra-high density overhead storage. Warehouse sections in large-area buildings may have the additional requirements of narrow aisles. Robotic equipment, ultra-high-density systems and buffer systems, as well as wire-guided forklifts, may need to operate along predefined paths. Consideration should also be given to extreme loading demands via heavy equipment installed in addition to loading from stored items.


Many retailers choose to install polished concrete finished surfaces in large-area installations. These floors are aesthetically pleasing, have lower upfront and maintenance costs, and have less potential liability for slips and falls. However, if floors are not flat enough, the polished surface makes imperfections such as bumps and dips very visible. Many retailers closely associate store branding with floor aesthetics, so the quality of concrete finishes is very important.


Floors that are not flat enough will not only require extensive repairs over their lifetime, but will put stress on robotic and other equipment. This results in unnecessary costs and wasted time for facility managers, maintenance personnel and building owners. Additionally, some of the benefits of flat floors are not immediately related to construction issues. For example, when forklifts and other moving vehicles can move easily over floors that are free of roughness, cracks, or irregularities, they can handle materials faster, improving plant productivity. facility. They can even navigate into tighter spaces, allowing for more consolidated storage and reducing the square footage required to operate a facility.

For the purposes of commercial and industrial floors, floor flatness (FF) measures deviations from a theoretically flat plane, i.e. the bump of a floor. Floor flatness (FL) is defined as a deviation from a horizontal plane. ACI’s Fmin values ​​represent a separate system from traditional FF and FL. An Fmin number is used to define the lowest acceptable flatness on super flat ground that has defined traffic patterns (where vehicle wheels are always in the same wheel path).

The role of certification

Another very large retailer plans to build about 60 distribution facilities in the United States. They have declared their intention to specify certified personnel for advanced leveling work (in addition to regular certified personnel, who have been required for more than 15 years) for the construction of the two distribution centers. equipment and stores.

Many local, national, and international building codes already require personnel certified by the American Concrete Institute (ACI) for various construction roles. But it can be beneficial to have ACI certified workers for positions beyond these required roles. As a result, project owners, including big-box store owners, are demanding more certified personnel on their job sites as well as certification from a wider range of ACI programs.

The ACI Specialty Commercial/Industrial Concrete Flatwork Finisher/Technician program was designed to set a higher minimum standard for all commercial/industrial concrete flatwork and to teach an in-depth knowledge of concrete codes and standards. Program participants gain an understanding of the various aspects of concrete construction, which saves them time and effort on the jobsite. Jobsite communications are also improved between certified individuals, as there is a common understanding of proper procedures, which reduces excessive rework and makes the overall project run more smoothly.

During a typical two-day program, hosted by various supporting organizations, certification seminars present information on the following. Particular attention is paid to commercial and industrial flatness requirements. The content of the seminar draws heavily from ACI CP-11(08), “Craftsman Workbook for ACI Certification of Specialty Commercial/Industrial Concrete Flatwork Finisher”.

  • Site preparation and setup environment
  • High quality concrete leveling materials
  • Pre-placement placement, concrete placement and consolidation
  • Application of surface treatments and finishing of different classes of floors
  • Surface tolerance issues
  • Hardening
  • Special considerations for silica fume
  • And more

Flat Concrete Finishing Certification is offered in the following categories, with designations of Associate (Technician), Finisher, Advanced Finisher (Finisher/Technician) which differ not only in the knowledge required to achieve certification, but also by the level of practical skill required.

The three categories themselves represent the different types of finished grading installation.

  • Concrete leveling certificate focuses on proper procedures and equipment for placing, consolidating, finishing, edging, grouting, curing and protecting concrete plates.
  • Decorative concrete leveling certificate focuses on placing, finishing, curing and protecting decorative concrete plates.
  • Specialized Certificate in Commercial/Industrial Flat Works Addresses additional areas of concern and offers several endorsements, or add-ons: The High Tolerance Floor Construction Endorsement requires an applicant to know how to handle fresh concrete to achieve floor tolerances that meet pre-set numerical level measurements and flatness; The Surface Treatments Addendum includes information on items such as the application and encapsulation of aggregate hardeners; The silica fume endorsement requires applicants to place, finish, control evaporation, and cure concrete with silica fume (also called micro-silica).

Those wishing to obtain their ACI certification as a Commercial/Industrial Flat Concrete Specialist Technician must pass a written exam and pass a performance exam, constructing an actual superflat slab using a vibrating lattice screed and/or of trowels, straight edges, control rods, channel floats, finishing blades and various hand tools.

Don’t lose an auction

Shortly after the initial offering of “ACI Specialized Commercial/Industrial Flat Concrete Finisher/Technician” in 2008, specifiers at big box stores and other commercial/industrial facilities began requiring that flat work crews have at least one ACI certified commercial/industrial finisher. For more than 13 years, the need for certified personnel has increased considerably. For example, one of the largest online retailers, which previously required the use of ACI flat finishers, added a requirement for ACI commercial/industrial flat finishers on every project. Considering the retailer has more buildings currently under construction than any other private entity – with more than 200 in the United States alone – this represents a surge in demand for ACI-certified flatwork specialists. In many of these facilities there are thousands of robots, the efficient operation of which depends on very high quality concrete floors in terms of flat and level floor tolerances as well as the minimum of cracks and defects. It is not acceptable to shut down a facility for floor repairs.

Another very large retailer plans to build about 60 distribution facilities in the United States. They have declared their intention to specify certified personnel for advanced leveling work (in addition to regular certified personnel, who have been required for more than 15 years) for the construction of the two distribution centers. equipment and stores. Yet another very large retailer has specified regular certified personnel for a similar period and also expects to require advanced pavers and commercial/industrial pavers soon.

Architects, engineers and big-box store owners are improving project quality by specifying more ACI-certified workers on flat work crews. Certified team members find that jobsite workflows are improved, time is saved, and rework is reduced. After all, it is in everyone’s interest to promote quality and maintain the highest standards in the industry.

About the authors

John W. Nehasil is General Manager, Certification, American Concrete Institute.

Bryan Birdwell, FACI is Principal/Principal Flooring and Paving Consultant, Structural Services Inc. and Chair of ACI C640 and Others Committee.

Jerry Holland, FACI, is the Vice President/Director of Design Services/Principal, Structural Services Inc. and the ACI C640 and Others Committee.


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