Estimating take-off is the process of quantifying the material and labor quantities associated with the project. The term take-off is also used to refer to the quantities themselves (often known as a bill of quantities).
Takeoff involves a detailed examination of the engineering drawings and deliverables to count the number of each item appearing on the drawings. The quantities of like items are
then summarized according to the control structure (WBS/RBS) of the project.
Once the take-off is complete, and total quantities for each like item summarized, the items can be costed (or priced), and the results added together resulting in the estimated direct field costs for the project.
Allowances are often included in an estimate to account for
the predictable but undefinable costs associated with project scope. Allowances are most often used when preparing deterministic or detailed estimates. Even for this class of estimate, the level of project definition may not enable certain costs to be estimated definitively. There are also times when it is simply not cost-effective to quantify and cost every small item included with the project. To account for these situations, an allowance for the costs associated with these items may be included in the estimate.
Allowances are often included in the estimate as a percentage of some detailed cost component. Some typical examples of allowances that may be included in a detailed construction estimate are:
• design allowance for engineered equipment;
• material take-off allowance;
• overbuy allowance;
• unrecoverable shipping damage allowance;
• allowance for undefined major items.
Generally, the process of “take-off” for the estimate is much more efficient when standard estimating guidelines are established and followed. This provides advantage enough when a single estimator is preparing a specific estimate, but is even more important when multiple estimators are working on the same project.
By keeping a uniform and consistent take-off process, the chance of error or omission is greatly reduced, and productivity is increased. Multiple estimators will find it easier to work on the same project; and if a personnel change takes place, it is much easier for a new estimator to pick up.
After the take-off is completed, the quantities can be extended, consolidated, and priced. If a procurement department or other resources will be utilized to investigate certain pricing (major equipment, large bulk material purchases, subcontracts, etc.), a listing should be compiled and sent to the appropriate person.