QUANTITY TAKE-OFF

A Vision To Clear Solutions.

QUANTITY TAKE-OFF:

The quantity “takeoff” is an important part of the cost estimate. It must be as accurate as possible and should be based on all available engineering and design data. Use of appropriate automation tools is highly recommended. Accuracy and completeness are critical factors in all cost estimates. An accurate and complete estimate establishes accountability and credibility of the cost engineer, therefore, providing greater confidence in the cost estimate. The estimate contingencies for programming purposes reflect the estimate confidence.

Importance of Quantity Takeoff and Required Documents:

The quantity of material in a project can be accurately determined from the drawings. The estimator must review each sheet of the drawings, calculate the quantity of material and record the amount and unit of measure. Each estimator must develop a system of quantity takeoff that ensures that a quantity is not omitted or calculated twice. A well organized check-list of work will help reduce the chances of omitting an item. The estimator must, also, add an appropriate percentage for waste for those items where waste is likely to occur during construction. The material quantity takeoff is extremely important for cost estimating because it often establishes the quantity and unit of measure for the costs of labor and contractor’s equipment.

Contract documents:

The contract is defined by the contract documents, which are developed from the tender

documents. In a logical order, these documents refer to the following subjects:

• Input from the client (task description).
• Output of the contract (specifications, results to be achieved).
•  Prices for the contractor's contribution.
• Responsibilities and procedures (liability, resources provided, time schedule,
• payment conditions, changes procedures, etc).

Contract documents are usually arranged according to the following sequence:

 General (for any project).

 Special (for a specialty area of the project).

 Supplementary (unique to a given project).

 Additional (during bidding or negotiation).

 Agreement form (for singing very important and particular clauses).

 Modifications (during contract fulfillment).

The complete contract agreement usually consists of the following documents:

 Conditions (general, special, supplementary).

 Drawing and specifications.

 Addenda.

 Agreement form.

 Modifications.

The most important document from the legal point of view is the agreement. It is sometimes called the contract. Since so many documents are included as contract documents, the agreement is the better term for this particular one. The form of the agreement can be standardized and used for many projects, or a unique document can be prepared for each project. The standard form of agreement prescribed by the American Institute of Architects has proved to be satisfactory and has been used on many building projects with good results. The form followed for non-building projects is often more

varied. Man: agencies have own standard forms, which are used on all their projects.

Information usually included in the agreement of three parts. The first part is a short introductory paragraph which defines the parties, gives the date of the agreement, and state that each party agrees to what follows. The second part contains the elements of contract and defines the work to be undertaken. The final paragraph confirms the agreement and provides space for signatures of the parties. Thus, the agreement usually composed of the following articles:

1. A short introductory paragraph.

2. Scope of the work.

3. Time of completion.

4. Contract documents.

5. Performance bond.

6. Contractor's insurance.

7. Owner's insurance.

8. Laws, regulations and permits.

9. Payments.

10. Extensions of time.

11. Changes in the work.

12. Owner's right to terminate the work.

13. Contractor's right to terminate the work.

14. Confirmation and signatures.

Quantity take-off: Why?

Owner perspective:

- Initial (preliminary) estimate of the project costs at the different stages of the project.

- Preparing the BOQ as a requirement of the contract documents.

- Estimating the work done for issuing the contractor payments.

Contractor perspective:

- Pricing different work items.

- Identifying the needed resources (Labor, Equipment, etc.).

- Project schedule.

- Preparing invoices for work done.

- Subcontractors’ payments.

- Review and control of crews’ production rates.

Quantity Development

After the scope has been analyzed and broken down into construction tasks, each task must be quantified prior to pricing. Equal emphasis should be placed on both accurate quantity calculation and accurate pricing. Quantities should be shown in standard units of measure and should be consistent with design units. Assistance for preparing “takeoffs” may be provided by others within the organization in support of cost engineering; however, the responsibility for the accuracy of the quantities remains with the cost engineer. Distinction should be made between “net” quantities without waste versus quantities that include waste or loss. This is necessary to ensure duplication does not occur within the estimate.

The detail to which the quantities are prepared for each task is dependent on the level of design detail. Quantity calculations beyond design details are often necessary to determine a reasonable price to complete the overall scope of work for the cost estimate. A simple example would be fabrication waste material that is a material cost to the project. Project notes will be added at the appropriate level in the estimate to explain the basis for the quantity calculations, to clearly show assumed quantity allowances or quantity contingencies, and to record quantities determined by cost engineering judgment that will be reconciled upon design refinement. Use the following recommended guidelines in quantity development:

- Coordinate the quantity takeoff process and plan with the estimator.

- Ensure full project scope is reflected within the estimate.

- Include a list of materials in quantity takeoffs. 

- Utilize a process that easily records the quantity development, i.e., document source and date, estimator name and date, location within the project, demonstrated calculations and additions such as waste or loss.

- Use a systematic approach similar to the construction methodology required.

- Check scales and dimensions on each drawing sheet.

- Highlight or mark drawing areas where quantities have been determined to ensure all scope is captured but not double counted.

- Consider items that have no material but still require cost, e.g., job office overhead (JOOH), task setup, training and certifications, and labor preparation.

- Develop quantities within a reasonable range for the work using decimals where critical.

- Add a certain amount of waste, loss, drop off, or length related to the material purchases for a bulk order. Ensure this addition is separate from the original quantity measured.

- Select a natural stopping point during work interruptions.

- Coordinate with designers if the design appears in error, if a better approach is discovered, or a value engineering process is warranted.

Bill of Quantities

The Bill of Quantities (BOQ) is defined as a list of brief descriptions and estimated quantities. The quantities are defined as estimated because they are subject to admeasurement and are not expected to be totally accurate due to the unknown factors which occur in civil engineering work. The objective of preparing the Bill of Quantities is to assist estimators to produce an accurate tender efficiently and to assist the post contract administration to be carried out in an efficient and cost-effective manner. It

should be noted that the quality of the drawings plays a major part in achieving theses aims by enabling the taker-off to produce an accurate bill and also by allowing the estimator to make sound engineering judgments on methods of working. Figure 2.1 shows a sample of a bill of quantities.