Narrow-strip concrete placements are the industry standard for narrow-aisle, defined-traffic warehouse slabs. To meet the tight flatness tolerances, usually Fmin 50 to 100, contractors perform narrow-strip construction by setting edge forms 14 to 20 feet apart and striking off the concrete with a vibratory truss screed. Though you can get the needed flatness with narrow-strip construction, the extra time and expense required to complete large floor areas with this method are major disadvantages.
This article describes how a construction team overcame these disadvantages by using the wide-placement method to build a 125,000-square-foot narrow-aisle warehouse floor. By using laser-guided fine graders and concrete screeds as well as riding trowels equipped with front-mounted straightedges, crews were able to place five 100-foot-wide by 250-foot-long strips within seven working days to a flatness tolerance of Fmin 65.