Ordering Check the weather forecast before ordering concrete. This information will help you decide if hot or cold weather precautions need to be made. As concrete temperatures increase, setting time shortens, leaving less time to complete the job. Reduced temperatures lengthen setting time. Concrete is ordered by the cubic yard.
Errors are common when calculating the quantity required.
To calculate the required volume, an irregularly shaped slab may be broken down into recognizable geometric shapes. These shapes are generally the rectangle, circle and triangle. Calculate the square feet of surface area for each individual section, and then add them to determine total surface area. Multiply the surface area by the thickness in feet to determine the total volume in cubic feet. Divide this value by 27 to obtain the volume in cubic yards.