Calculating Composite Production Values for Multi-Item Assemblies

By:  Charles B. Antone

In the following brief, I will show the underlining governing equation for calculating composite production values for multi-item assemblies.  A multi-item assembly can be represented in a multitude of forms, but in this discussion I will focus primarily on calculating production based construction cost estimates. Once understood, the composite production value underlining equation can be used forensically, as well as as a means to track the real-time labor usage on an active construction site.     

 Governing Equation:

Where:

CP = the composite production value
n = individual item production values


Example:

If one was creating a cost estimate, based on production values, for an interior partition, it may take the following form:

Table 1.0 is the listing of the overall attributes of the example wall assembly.

Table 1.1 is the breakdown of the individual labor items that make up the wall assembly.

Please note that each individual labor item in the composite assembly must be in the same unit of measure (i.e. per linear foot or alternatively per square foot).  This may require conversion.  In this example, we are looking for the linear foot of the overall assembly per man-day of labor, so each item has been converted, as needed.

To calculate the composite production value, using the data in Table 1.1, one would proceed as follows:



As a check, one can perform the following calculation:

Conclusion:

Using the CP calculation one could but is not limited to:

• Measure the overall production of a multi-labor itemed assembly against their original cost estimate, as an ongoing measure of profitability.

• Approximate the overall manpower needed to install a multi-labor itemed assembly given a project’s duration.

• Algebraically approximate individual labor items when the composite production value  as well as the n-1 of the items are known.