What Are Shop Drawings in Construction? Understanding Their Role

May 21, 2024

Construction projects rely heavily on detailed plans to ensure precision, coordination, and effective execution from conception through completion. Two critical types of drawings — construction drawings and shop drawings — are fundamental to this process. Understanding the differences between these drawings, their creation, and their purposes significantly impacts the success of a construction project.

Definition and Purpose

Construction Drawings (CD Sets)

Construction drawings, often labeled as IFC (Issued for Construction) or working drawings, are prepared by architects or engineers. These plans offer a comprehensive visualization of architectural and structural elements before construction begins. They serve as a basis for contractors to price out the project, estimate labor, and calculate material consumption and overall costs.

Shop Drawings

Shop drawings are produced by contractors, sub-contractors, manufacturers, or suppliers. They include highly detailed information crucial for component manufacturing and installation. Shop drawings encompass precise details about beams, trusses, equipment layouts, and other components, enabling accurate coordination and assembly.

Timing of Creation

Construction Drawings

These drawings are created before the actual construction begins. They provide a detailed visualization of the architectural components and structures, including estimated dimensions, fixtures, materials, and performance specifications.

Shop Drawings

Shop drawings are prepared after a contract is signed and before the start of the construction project. Derived from contract drawings, these detailed plans are developed to adhere to project specifications.

Responsibility for Creation

Construction Drawings

Architects or engineers create construction drawings at the owner's request.

Shop Drawings

Contractors, sub-contractors, manufacturers, or suppliers prepare shop drawings after the contract is established.

"shop drawing detail" by Caliper Studio is licensed under CC BY-NC-SA 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/2.0/.

Accuracy and Detail Level

Construction Drawings

Since construction drawings are prepared before contractors are hired, they may contain errors or ambiguities. These drawings focus on the overall project intent rather than specific details and are often marked with “Verify-in-Field” labels to confirm measurements and actual conditions.

Shop Drawings

Shop drawings offer precise dimensions, timestamps, and assembly details essential for fabricators. They function as an assembly manual developed during the construction process, often requiring approval from the construction team.

Liabilities and Risks

Construction Drawings

These drawings are labeled "Not for Construction" to mitigate risks for owners before actual construction begins. They represent the entire scope of work and provide a reference for contractors to budget work and produce change orders.

Shop Drawings

Shop drawings reflect the contractor’s complete work scope and actual field conditions. These drawings are referred to multiple times as the project progresses, requiring detailed drafting to ensure accurate fabrication and installation.

Inclusions and Components

Construction Drawings

Construction drawings cover various details, including elevations (interior and exterior), plans (framing, utility, roof, electrical & lighting), sections (building and walls), schedules (doors and windows), finishes, and MEP (Mechanical, Electrical, Plumbing) information.

Shop Drawings

Shop drawings include component identification, interference and adjacency data, tagged components, assembly details, material identifiers, fabrication standards, installation and erection data, and notes on revisions with descriptions.

Role of 3D BIM Modeling

Utilizing 3D Building Information Modeling (BIM) enhances the accuracy, reliability, and quality of both construction and shop drawings. BIM models help reduce errors, ambiguities, and delays by providing comprehensive information for architects and contractors.

By thoroughly preparing diverse drawing sets and leveraging advancements like 3D BIM modeling, it is possible to achieve successful and precise outcomes in construction projects. Understanding the distinct roles and benefits of construction drawings and shop drawings is essential for efficient project execution.

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