Ensure optimum amount of modularization vs pre-assemblies
The objective of modularization is to move as much labour offsite as possible, but some modules that have lower amounts of labour density may not be practical to modularize. In these cases, they would be converted from modules to pre-assemblies.
Labor density is number of hours required per volume of module. The ideal module would have a high labor density. The most optimum module would require the module labor density to be above the location minimum labor density. This will vary depending on the location in the world the project is located. The below Figure demonstrates that there is an optimum level of modularization.
The green line in the Figure will move based on a calculation used to determine if the site labour cost is greater than the shop labour plus the additional cost for steel, engineering and transportation to modularize. A sensitivity cost analysis should be performed to determine if the amount of modularization chosen will add value to the project and schedule savings should also be taken into consideration. DyCat Solutions has a cost analysis tool that can be utilized to determine the optimum level of modularization.
Another rule of thumb would be if there is 60% or more structural steel than any other commodity, the module would not be practical and pre-assembly would be a preferred option.