For all engineering works it is required to know beforehand the probable cost of construction known as estimated cost. If the estimated cost is greater than the money available then attempts are made to reduce the cost by reducing the work or by changing the specifications. In preparing the estimate, the quantities of different items are calculated by simple maturation method and from these quantities the cost is calculated.

It is a bill of quantities that is organized according to trades in the order in which they appear in the building and a sum of it given. It is also called sectional bills of quantities because work is divided into sections in which they appear in the construction project such as excavation works, roofing, concreting, etc.

Cost incurred on site, factors, situations, and items that affect the cost of a project and are temporary in nature but assist in the smooth running of the project. They include hoarding, security, power, and water. They affect the overall cost of the works but cannot be attributed to any particular section of the works.

Definition of the term “Law” There is generally no acceptable definition of the word law. Different schools of Law define it differently. Some important definitions of law include: - 1. Woodrow Wilson, has defined law in the words “That portion of the established thought and habit which has gained distinct and formal recognition in the shape of uniform laws, backed by authority and power of government” 2. According to Holland, “A law is a general rule of external human action enforced by sovereign political authority” 3. In the words of Salmond, “Law is a body of principles recognized and applied by the state in the administration of justice”. 4. Law may also be defined as” a rule of human conduct, imposed upon and enforced among the members of a given state”. From the above definitions, we may conclude that law refers to “a set of rules or principles that govern the conduct of affairs in a given community at a given time, whereby machinery is provided for an aggrieved party to enforce his right in case any of these rules or principle is broken.