Cost Breakdown Structures


A cost breakdown structure (CBS) is simply a way of breaking down and organizing costs in a structured fashion. If you have experience in project management, you will probably be familiar with the concept of a work breakdown structure (WBS). The Mandrel CBS is very similar, but since Mandrel can be used for other applications besides project budgets, we use the more generic term cost breakdown structure.


The units from which a cost breakdown structure is built are called cost items. Other terms you may be familiar with are tasks or line items.


You must create a cost breakdown structure before you can input any cost data.


Creating a Cost Breakdown Structure

A cost breakdown structure is shaped like an inverted tree. At the top is the level zero item, from which the entire structure descends. Mandrel creates the level zero item for you when you open a new datafile. You then fill in the lower levels (level 1, level 2, and so on).


Mandrel provides capabilities to add, delete and move cost items in a cost breakdown structure. CBS numbering is automatically adjusted whenever a change is made to the structure, so as to remove any gaps and duplications in the numbering caused by the change. This means you don't have to think about the mechanics of adding, deleting or moving items, only the end result you want to achieve.


You can use either a decimal numbering system (1.2.3. ...) or a fixed digit numbering system (1230, or 12300, etc.). Fixed digit systems can use anywhere from 2 to 9 digits.