The contract drawings and specifications prepared by the design professionals are indicative and are generally meant for determining the tender pricing and for planning the construction project. In many cases, they are not sufficient for installation or execution of works at various stages. More details are required during the construction phase to ensure the specified quality. These details are provided by the contractor on the shop drawings.
Shop drawings and material submittals (submittals) are a critical element of every construction project. The contractor has to submit the material specifications to the owner/consultant for review and approval. They are essential to identify materials which may have a long lead time that could impact the proposed schedule for the project. The detailed procedure for submitting shop drawings, materials, and samples is specified under the section titled “SUBMITTAL” of contract specifications.
Shop drawings are used by the contractor as reference documents to execute/install the works. A detailed shop drawing helps the contractor achieve zero defects in installation at the first stage, thus avoiding any rejection/rework. Based on the contract drawings, the contractor prepares shop drawings and submits them to the consultant for approval. All the work is executed per the approved shop drawings. These drawings indicate the size of openings, sleeves, and location/level references with the help of detailed elevations and plans of the building, fully coordinating the requirements of all the trades. Detailed sections are also shown for complicated areas. Example of shop drawings are the Bar Cutting List, Bar bending schedule, and bar placement drawings of reinforced concrete.
All the materials, equipment, and systems specified in the contract documents need prior approval from the owner/consultant. If the contractor is unable to obtain the specified product or is unable to find an approved equivalent product, then he or she may propose a substitute product for the approval of the consultant/owner for their review and approval. Upon receipt of material at site, the contractor submits the material inspection report.
The work at site is executed per approved shop drawings with approved materials only. With materials and components received on site, records of receiving inspection and testing provide documented evidence of quality. With building works, records of in-process inspection and testing virtually become a register of the stage-by-stage acceptance of the works.