AdvancedTopic 102 of 112Civil & Structural
Estimating and costing
Quantities and rates produce project budgets.
In depth
Quantity take-off, unit rates, overhead and profit generate cost estimates: preliminary (parametric), detailed (bill of quantities) and tender estimates. Accuracy improves with design development. Contingency covers uncertainty. Cash flow and escalation matter.
Key points
- Direct and indirect costs
- Productivity rates
- Bill of quantities
ExampleA concrete slab estimate multiplies volume by rates for concrete, steel, formwork and labour.
What is Estimating and costing?
Quantities and rates produce project budgets.
Why is it important to understand estimating and costing?
Estimating and costing turn quantities and rates into a budget, which is needed to tender competitively and control spending.
What is a bill of quantities?
A document listing the quantities of each item of work, which allows bidders to price the project on a common basis.
What is a unit rate?
The cost of one unit of work, such as one cubic metre of concrete placed, including labour, materials and equipment.
How is Estimating and costing used in practice?
Typical applications include preparing a bill of quantities for a school building, estimating the cost of excavation for a foundation and checking a contractor's tender price against the estimate.
What should I learn before Estimating and costing?
Study "CPM and PERT" first (topic 101 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of Estimating and costing?
Direct and indirect costs. Productivity rates. Bill of quantities.
Can you give an example of Estimating and costing?
A concrete slab estimate multiplies volume by rates for concrete, steel, formwork and labour.
What comes after Estimating and costing?
The next topic is "Contracts and tendering", which builds directly on this one.
How difficult is Estimating and costing?
It is classed as Advanced in Civil & Structural (topic 102 of 112). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Civil & Structural.