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When asked to define “design error,” not all disciplines in the construction process agree on a common definition. Depending on which discipline you address, the owner, the designer or the contractor there will be a common understanding surrounded by varied conclusions, “a mistake.” From the basic definitions of “design” and “error” we conclude that a design error is a deviation from a drawing or specification, also including omissions and ambiguities. It is the seriousness of this error that must be considered to determine its consequences on the overall outcome of the project One of the most important challenges facing management today is controlling the all too frequent cost and schedule overruns that effect the construction industry (Diekmann and Thrush, 1986). One of the major issues to control growth in project costs and time is the reduction of design errors.
The owner, designer and contractor all have different interests in, or uses for the design of a facility. But what they do share is the commitment to complete the project safely and within a given budget and completion time. There are many initiatives being conducted to control the growth of cost and schedule within the construction industry.
The major issue is “accuracy of the drawings,” or the number of design errors, omissions and ambiguities within the plans and specifications that affect the quality of the facility. Inadequacies in the plans and specifications are the major causes of changes to the contract So much emphasis is placed on the issue of time and cost that quality takes a back seat The quality of the project depends on the conformance of the objectives and requirements from the owner. An informative quality management technique will provide an agreement to procedures and definitions among the principle parties for the project. Since design errors have an impact on the outcome of the effectiveness of the contractor’s effort on the project it is essential that all parties determine what the definition of a design error should be. When asked to define design error, not all disciplines in the construction process agree on a common definition. From the basic definition of design and error it can be determined that a design error is a deviation from a drawing or specification. It is the seriousness of this error that must be considered to determine its consequences on the overall outcome of the project


Design errors indicate the total design in-effectiveness of a project. Major design quality problems occur during construction when errors, omissions and ambiguities in plans and specifications become evident (Davis and Ledbetter, 1987). This statement directs that the inadequacies in the plans and specifications are the major causes of changes to the contract. There have been extreme examples of design errors such as numerous building collapse in Nigeria – projects that have wrought disaster after the construction are completed. These are examples of design errors that escaped the close scrutiny of all parties. One or two major errors that can be corrected with only cost considerations and little effect on the schedule can impact projects. The projects that really suffer are those with many small errors (design, rework or change of scope) which when finally added up cause major impacts on the cost and schedule growth. Through Davis and Ledbetters research it was determined that “accuracy of the design documents” was the most critical of the criteria used in the initial evaluation of design effectiveness. This accuracy was further described as the concern for the frequency and impact of errors in the specifications and drawings. This is due to the fact that the drawings and specifications are the most “readily identifiable outputs of the design process.” It is evermore important that the quality control of designs be addressed during the planning phase and closely monitored during the construction phase.

The main aim of the study is to investigate how design errors can affect the initial cost of a project. The specific objectives are:

  • To determine what constitutes a design error.
  • To examine the contributing factors to design errors in Nigeria.
  • To examine how these factors can affect initial cost and growth of a project.


  • What makes or contributes to a design error?
  • What are the factors that lead to design errors?
  • What effect can design errors have on initial cost and growth of a project?


Hi: There is no significant relationship between design error and initial project cost.
Ho: There is significant relationship between design error and initial project cost.

This study gives a clear insight into the various ways in which contractors in the construction companies in Nigeria can maximise profits and reduce initial cost through effective and efficient contract planning and management. The study also gives a clear insight into the various effects of design errors on the cost of a project. The findings and recommendations of the researcher will help in building a strong and better project management guideline for contractors in Nigeria.

This research focuses mainly on the investigation of design errors on initial cost of a project. Results and recommendations may not be used to generalise other construction companies in Nigeria, as the researcher could not cover a wider scope due to financial and time constraints.
Based on the findings of this study other possible researchable areas may include studies on the various effects of other aspects of contracts such as contract laws in Nigeria and contract management and control.


The only limitation faced by the researcher in the course of carrying out this study was the delay in getting data from the various respondents. Most respondents were reluctant in filling questionnaires administered to them due to their busy schedules and nature of their work. The researcher found it difficult to collect responses from the various respondents, and this almost hampered the success of this study.


  • Design: The basic definition of design, according to Webster, is “the making of drawings or plans to plan and fashion the form and structure of an object to have intentions or purposes.” The quality of planning and design is one of the primary factors of success in any project endeavor (Chalabi, Beaudin and Salazar, 1987). The design includes every aspect of the facility construction including operation and maintenance. The design incorporates a set of specifications to guide the contractor in developing his means and methods of construction. Figure 2-1 shows the traditional flow diagram of a design/construction method.
  • Error: An error is defined, according to Webster, as “a deviation from accuracy or correctness; a mistake, as in action or procedure; an inaccuracy, as in speaking or writing.” There are basically three types of errors: imperfections, non-conformance and omissions. Imperfections are deviations in details that have no affect on the assembly or facility (Davis and Ledbetter, 1987).
  • Design Error: From the evaluation above a simple definition of design error is “a deviation from the plans and specifications.” It is not the intention of this definition to include any cost or schedule growth or insinuate its root causes or legal responsibility. It is the responsibility of the owner, designer and contractor to establish the criteria in order to make a reasonable determination for responsibility. The survey shows a common theme, that of a mistake or error in the design. The survey also indicates several reasons why design errors exist and who cause them. This provides evidence that there is not a concise definition within the construction industry.
  • Contract:  Erikson (2002) defined Contract as an agreement that creates an obligation binding upon the parties thereto. The essentials of a contract are as follows: (1) mutual assent; (2) a legal consideration, which in most instances need not be pecuniary; (3) parties who have legal capacity to make a contract; (4) absence of fraud or duress; and (5) a subject matter that is not illegal or against public policy.
  • Contract Planning: According to Simmons (2007), Contract planning is the process of systematically and efficiently managing contract creation, execution and analysis for maximising operational and financial performance and minimising risk.
  • Contractor: General contractor, organization or individual that contracts with another organization or individual (the owner) for the construction of a building, road or other facility.
  • Profit:  Tucy (2008) defined profit as the difference between the purchase price and the costs of bringing to market
  • Initial Cost: Initial costs are fixed, one-time expenses incurred on the purchase of land,buildingsconstruction, and equipment used in the production of goods or in the rendering of services. Put simply, it is the total cost needed to bring a project to a commercially operable status. Whether a particular cost is capital or not depend on many factors such asaccountingtax laws, and materiality.

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