It is commonly understood in the construction industry that unit price contracts entitle the contractor to payment for the actual executed quantities. However, a question arises as to whether this statement holds when the contractor fails to undertake his duty to seek clarification for patent omissions in the bill of quantities during the tender stage, which can result in these omissions surfacing as changes during the construction stage with a possibly unanticipated and significant cost overrun borne by the employer. All too often, in this case of clash of principles between the contractor’s right under a unit price contract for compensation of actual quantities, including those resulting from patent design omissions, and the principle of not compensating the contractor due to his failure to seek clarification of a patent design omission, there is a heated debate in the industry between employers (including their representatives and project management firms) and the contractors. Contractors argue that the obligation to provide a complete design rests with the employer and the action of not compensating the contractor for actual quantities executed for any cause confuses the delineation between a unit price contract and a lump sum contract. Employers, on the other hand, argue that the contractor gained an unfair advantage by not identifying patent omissions during the tendering stage and consequently submitting a non-responsive and misleading tender price.

Although this clash of principles is often encountered in the construction industry worldwide, it is seldom discussed in the literature. This paper sheds light on this topic and elaborates on the two opposing views. Case studies from three major projects in Egypt are discussed to illustrate the complexities of this scenario and how it was handled on each project. The paper concludes with a number of considerations and recommendations to construction practitioners that can contribute to a balanced and fair outcome to the contracting parties.