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Shop Drawings vs. As-Built Drawings: What is the Difference?

Bojan Ladjinovic on September 27, 2024
Author: Dejan Jovanović| Rebar Detailer | NS Drafter

 

In the construction industry, technical documentation plays a critical role in the successful planning, execution, and monitoring of construction projects. Two primary types of technical drawings that are of utmost importance during this process are shop drawings and as-built drawings. These drawings serve different functions, but both types of documentation contribute to achieving precision and quality at every stage of construction. In this article, we will take an in-depth look at the differences between shop drawings and as-built drawings, their roles, and how each of them contributes to the construction process.

Shop Drawings – Definition and Function

Shop drawings are specific, technically precise illustrations created by manufacturers, contractors, or subcontractors that contain all the necessary details for the production or installation of certain elements in a construction project. These drawings are far more detailed than the original architectural and engineering drawings, as they focus on exact dimensions, materials, connections, and installation methods. They show how elements such as windows, doors, reinforcement, ventilation systems, or electrical installations will actually be fabricated and installed on-site.

Shop drawings serve as detailed guides for executing specific parts of the project. Unlike basic architectural or engineering drawings, which provide a general overview of the building, shop drawings focus on the details of each individual element. Their purpose is to reduce the possibility of errors during execution, ensure coordination among different teams, and improve construction efficiency.

For example, shop drawings for steel structures will show the exact dimensions, joints, bolts, and weld points, ensuring that all parts are properly connected and integrated into the building as a whole. Additionally, shop drawings allow contractors to plan work processes in advance and identify potential issues before they are implemented on-site.

Shop drawings include precise technical specifications, such as dimensions, materials, and details on how elements are connected. They also contain information on the production process, logistical challenges, and methods of installation on-site. The drawings go through rigorous stages of review and approval by architects and engineers before production or installation begins.

Shop drawings vs As-Built Drawings

As-Built Drawings – Definition and Function

As-built drawings are technical drawings that depict the final state of a project, showing how the structure was actually built compared to the planned state presented in the original architectural and shop drawings. They document all changes and adjustments made during construction, whether due to unforeseen on-site issues, errors in the initial design, or specific client requests.

As-built drawings are crucial for documenting the final appearance of the building. They allow owners and facility managers to understand the exact configuration of all systems and components, which is essential for future maintenance, repairs, or renovations. Without as-built drawings, any intervention on the structure would be much more complicated, as all information would need to be re-verified on-site.

One of the key goals of as-built drawings is to ensure that all contractors document any modifications made during construction. For instance, if changes were made during the installation of the HVAC system compared to the shop drawings due to unexpected field conditions, those changes must be reflected in the as-built drawings. This ensures that all future users of the building, including owners, managers, and technical staff, have accurate information about the actual state of the structure.

As-built drawings often contain hand-drawn modifications to the original shop or architectural drawings, including changes in dimensions, materials, or installation positions. They may also include photos or notes that document specific modifications made on-site. These drawings are typically the final set of technical documentation handed over to the building owners and are often part of the legal documentation contractors are required to provide after project completion.

Comparative Analysis: Shop Drawings vs. As-Built Drawings

While both types of drawings are used during the construction process, they differ in terms of when they are created, their purpose, and the level of detail.

Purpose and Timeline

Shop drawings are created during the preparation phase of construction, and their primary function is to ensure that all technical elements are precisely planned before manufacturing and installation begin. They focus on the individual components of the building, providing detailed information about their production, delivery, and installation.
As-built drawings, on the other hand, are created after the construction project is completed and serve as documentation of the actual condition of the structure. Their purpose is to record all changes and deviations from the original plans, providing an accurate depiction of what was ultimately built.

Technical Details and Precision

Shop drawings are typically much more detailed when it comes to the specifics of individual building components. For instance, shop drawings for a steel structure might show the exact dimensions and position of each steel beam, including joints, bolts, and the specific materials to be used.
As-built drawings do not focus on the technical details of each element in this way but rather on depicting the final position and condition of each system and component within the building. They are often more concise but invaluable for future building maintenance.

Review and Approval Process

Shop drawings undergo detailed review and approval processes, including multiple iterations of review by engineers, architects, and contractors. These reviews ensure that the drawings accurately reflect the project’s technical requirements before moving on to the fabrication phase.
As-built drawings, however, do not require such a level of review. They are essentially a record of the building’s final state, and although they may be reviewed by the client or the building owner, their primary goal is to provide accurate documentation of the final construction.

The Role of Shop and As-Built Drawings in Successful Construction Projects

Both types of drawings play a crucial role in ensuring the success of a construction project.

Shop Drawings and Their Role in the Preparation Phase

Shop drawings help contractors and subcontractors precisely understand all the technical requirements of the project. Without them, there would be a significant potential for errors during construction, which could result in delays, increased costs, or even structural issues. For example, shop drawings for concrete reinforcement enable on-site teams to accurately place the rebar according to the engineer’s specifications, ensuring that the building is structurally safe and stable.

As-Built Drawings and Their Role in Future Maintenance

As-built drawings are essential for the long-term maintenance and renovation of a structure. They allow technicians and engineers to understand how different systems are installed and how they function, making future interventions on the building easier. For instance, as-built drawings can show the precise location of underground installations, helping to avoid potential damage during later construction work.

Conclusion

In the construction industry, shop and as-built drawings play distinct but complementary roles. While shop drawings are key for the planning and preparation phase, as-built drawings are essential for the long-term management and maintenance of buildings. Understanding their roles and correctly applying both types of documentation is vital for the successful execution of construction projects and ensuring the longevity and functionality of structures.

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