How is the finish of a concrete slab tested for flatness?

The finish of a concrete slab is tested for flatness primarily by using a straight edge to check for deviations from the floor's intended grade. This method is effective because it allows for precise measurements along the surface of the slab. By placing a straight edge across the slab, any high or low spots can be easily identified. This technique relies on the flatness criteria defined in various standards and ensures that the finished surface meets the required specifications for both aesthetic and functional purposes.

The use of a straight edge provides a clear visual indication of variations in elevation, enabling the finisher to assess the quality of the work accurately. This method can identify abnormalities that may affect the placement of flooring materials or the overall drainage of the area.

While laser levels are advanced tools for checking elevation and grade, the straight edge method is a traditional and widely accepted method for testing flatness directly on the surface. Visual inspection alone lacks the precision needed to quantify flatness and can often lead to subjective judgments. Measuring the depth of the concrete may provide information about the thickness but does not assess the flatness of the finished surface itself.