Surveying: Why Get an Estimation?

An estimate is necessary to give the owner a reasonably accurate idea of the cost to help him decide whether the work can be undertaken as proposed or whether it needs to be curtailed or abandoned. This article looks into what is involved in the Estimating process.

Estimating Materials

From the estimate of a work, it is possible to determine which materials, and in what quantities, will be required for the work so that the arrangements to procure them can be made.

In making estimates for materials the following are relevant:

• Compliance of materials with specification: alternative materials may be cheaper and the estimator can price these subject to the contractor’s approval.

• Cost of transport: sometimes small loads or part loads can cost additional charges.

• Accounting for fixed sizes: a job may require a certain size but the supplier only provides material in fixed sizes. Obviously more has to be ordered than is needed. Consequently, this can be considered as waste or, alternatively, the surplus might be used on another project which will accrue storage costs.

• Quantities must be recorded; such as the number of bricks per square metre of a wall or the amount of paint required to cover an area.

• Unloading and distribution: costs can range from the initial cost of removing bricks from a lorry, for example, to the movement of materials around the site by a fork-lift.

• Waste: this can range from theft/vandalism to cutting materials to fit and includes other things like damage, breakages and incorrect use.


Estimating Labour

To estimate the labour costs, it is recommended to use the Code of Estimating Practice advice. Normally labour is calculated on the basis of an hourly rate.
This is calculated by using the formula:

Hourly rate = annual cost of employment / hours worked annually.

The annual cost of employment includes aspects such as holidays and overtime variation due to weather.
In calculating labour costs it is important to be aware of factors that may increase the nominal cost such as importing skilled labour unavailable in the location, and paying travelling and subsistence expenses.

Estimating Plant

To estimate plant requirements it is first of all necessary to specify what plant is required for specific and general operations. For example, a forklift will be required for many different aspects of the project whereas a crane might only be required for lifting roof trusses into place.

Next the source of each item of plant must be identified. Some plant may be owned and maintained by the contractor already whereas other plant may need to be purchased or hired/leased. Following this, the next step is to establish the prices for each item. For owned plant, the contractor may have an internal rate already established whereas for externally acquired plant, the prices will be available from the hire or leasing companies. In the case of hire or lease, alternative quotes should be considered. It is important to calculate the all-in hourly rate of plant based on:

• Plant cost per hour including licences, training, maintenance,
Depreciation and storage

• Fuel and lubricants to be required during the project for each item of plant

• Other overheads such as replacement tyres

• Operator all-in-rate based on the national working rule agreement.


Estimating Time

The estimate of a work and the past experience enable one to estimate quite closely the length of time required to complete an item of work or the work as a whole whereas the importance of knowing the probable cost needs no emphasis. Estimating materials, labour, plant and time is immensely useful in planning and execution of any work.

Estimating often involves the following:

• Site Investigation
Site investigations are crucial to the success of an estimate. It is necessary to examine and document access restrictions, area climate, utilities, construction facilities and other conditions unique to the site.

• Quantity surveys
Drawings are studied for interferences and conflicts, omissions or duplications. Plan views are compared to details and sections. The quantities are evaluated for waste amounts and included as appropriate.

• Construction methods
Individual parts of the project are analysed for construction methods. The estimator looks at the scope, conformance to the documents and needs of the project. This involves the time of year for construction(weather conditions), completion status of other work (ease or difficulty) and other site specific requirements.

• Pricing of materials and equipment
Once the materials and equipment are identified, the estimator sometimes solicits vendor quotations. These are documented on individual vendor quote sheets and kept as part of the estimate backup information.

• Specific overheads
An integral part of each estimate is the cost of the overheads on the project. These include items such as mobilisation and demobilisation, staffing, temporary buildings and construction, temporary utilities, job office expenses, small tools and consumables, insurance, taxes, home office support and finance expenses.

• Labour analysis and wage rates
Man-hours are determined from experience. Wage rates are detailed and documented. The total hourly rates include amounts for wages, fringe benefits and payroll burdens. Each craft then has applicable foremen and general foreman incorporated into the crew.


This article has been put together by the distance learning organisation Start Learning who are experts in home study.

If you want to find out more about Advanced Surveying or many other distance learning courses please browse their website: Start Learning

Kerrana McAvoy
Academic Director – Start Learning
Start Learning