What Shop Drawings are and their importance in Construction

In the construction sector, design accuracy and coordination between the various phases (from design to execution) are crucial elements to ensure the successful outcome of a project. Within this dynamic, the role of shop drawings is positioned. These are detailed technical documents produced by suppliers and subcontractors that translate design intentions into operational guidelines for the production and installation of specific components.

Although sometimes confused with other detailed technical documents (such as construction drawings), shop drawings are distinguished by their purpose and content. They represent the operational link between the design phase and the execution phase, offering a level of detail that prevents inconsistencies on site, optimizes processing times, and ensures that each element is produced in accordance with the required technical specifications.

In this article, we will analyze in detail what shop drawings are, who is responsible for them, and why they play a strategic role in the construction process. We will also provide some concrete application examples, with particular attention to steel structures and MEP (mechanical, electrical, and plumbing) systems.

Before we begin, it is important to know that today it is possible to create graphic project documents (such as plans, sections, and elevations) directly from a BIM model, even without using specific BIM software. With an online drawing creation software, you can generate any type of technical drawing from IFC models, without having to rely on the professional who created the project or install BIM authoring software. Discover all the details about shop drawings in this article and start creating them too with this innovative solution!

Shop drawings: what they are and what their purpose is

Shop drawings are graphic documents that represent a highly detailed version of specific elements of a construction project. Unlike technical drawings produced by the architectural or structural designer, shop drawings are developed by those responsible for the production, prefabrication, or installation of a component, such as a window installer, a metal carpenter, or an MEP installer.

Their main objective is to provide all the necessary information for the physical realization of an element, including materials, measurements, tolerances, assembly methods, and interfaces with other construction systems. They thus serve as an operational guide for the workshop, factory, or construction site, ensuring that what is built corresponds to the design intentions and technical requirements of the work.

In addition to dimensional aspects, shop drawings often include annotations, codes, construction details, reference numbers, exploded views, and assembly diagrams. These features make them essential tools for the accurate production and installation of components.

It is important to emphasize that shop drawings do not replace project drawings but rather integrate and translate them into practical operational instructions, sometimes introducing modification proposals (known as shop drawing submittals) to be submitted for approval by the designer or project manager.

What are Shop Drawings?

Differences between shop drawings, working drawings, and as-built drawings

In the construction process, terms like shop drawings, working drawings, and as-built drawings are often confused, but they actually refer to distinct documents, each with a specific function and placed in a different phase of the project lifecycle.

Here is an overview of the main differences:

• working drawings: prepared by the designer (architectural, structural, or systems), represent the detailed and executable version of the project to be realized. They contain all the technical information necessary for the execution of the work (measurements, materials, construction details, and regulatory references). They are the official basis on which the construction intervention is founded;
• shop drawings: developed by suppliers or subcontractors, focus on specific components (e.g., prefabricated elements, systems, fixtures). They are extremely detailed and operational, and serve to guide production, assembly, and installation. They may also contain proposals for modifications to the initial project, subject to approval;
• as-built drawings (drawings “as constructed”): prepared at the end of the work, document the project as it has actually been realized. They include any changes made during the work and represent a fundamental tool for the maintenance, management, and future modifications of the building.

Differences between Shop Drawings, Working Drawings, and As-Built Drawings

How are shop drawings created and approved?

The preparation of shop drawings involves various actors in the construction process, each with a well-defined role. These documents are not produced by the main designer, but by those who are directly responsible for the material realization of a part of the work, particularly in cases where prefabricated components, specialized processing, or complex installations are required.

Who creates them?

Shop drawings are generally created by:

• specialized suppliers and manufacturers, such as metalworking companies, prefabricators, window manufacturers, continuous facade producers, etc.;
• subcontractors responsible for MEP systems (mechanical, electrical, plumbing), HVAC, fire protection, or other complex technical systems;
• technicians and CAD or BIM drafters within the executing companies, or external ones specifically hired for this activity.

These figures, working from executive drawings and BIM models, develop technical documentation that meets not only the design specifications but also the needs of production, logistics, assembly, and coordination with other elements of the work.

Who approves them?

Once drafted, shop drawings must be submitted for verification and approval. This step is crucial to ensure consistency with the original project and to avoid errors or interference on site. The figures involved in the approval include:

• the responsible designer (architect, structural engineer, or systems engineer), who verifies technical compliance with the executive drawings and design specifications;
• the site manager, who assesses the adherence of the drawings to contractual and regulatory requirements;
• the BIM coordinator or BIM manager, when the project is developed in a BIM environment, to check for interferences and information consistency between models.

Only after formal approval can shop drawings be used as a basis for the production and installation of components on site. In case of observations or requests for modifications, the supplier must update the documents and resubmit them for a new review cycle (shop drawing submittal).

The importance of shop drawings in the construction process

In the modern construction context, characterized by increasingly complex projects, tight timelines, and a high level of specialization, shop drawings represent an essential tool to ensure order, consistency, and quality in the realization of the work. These drawings play a fundamental role, especially for the following aspects:

• coordination between disciplines and prevention of interferences: one of the main advantages of shop drawings is their role in coordinating between the various design disciplines (structures, architecture, systems). Thanks to their level of detail, it is possible to identify potential inconsistencies, overlaps, or geometric conflicts between components (for example, between a duct and a structural beam) in advance, avoiding issues that would otherwise arise only during the construction phase, with consequences in terms of delays and costs;
• quality control and reduction of errors on site: shop drawings serve as the operational basis for the production and installation of custom components, often prefabricated or pre-assembled. Their precision allows for minimizing tolerances, standardizing processes, and drastically reducing execution errors. Additionally, they provide clear instructions to operators on site, helping to simplify assembly phases and improve quality control;
• optimization of time and costs: careful planning based on approved shop drawings allows for optimizing the sequence of operations, avoiding interruptions or rework, and reducing waste. This translates into greater efficiency in the construction process and, consequently, a reduction in the overall time and costs of the project;
• support for digitalization and BIM: in an increasingly digital-oriented context, shop drawings represent a bridge between the BIM information model and the reality of the construction site. If generated directly from updated IFC models, they help maintain consistency between design, fabrication, and construction, facilitating the monitoring and traceability of operations.

Advantages of Shop Drawings

Practical Applications of Shop Drawings

Shop drawings find extensive application in all contexts where it is necessary to transition from a conceptual design to a concrete and detailed realization. They are particularly useful for prefabricated, customized, or technically complex elements, whose correct installation requires a high level of precision. Below, we analyze two key areas where the use of shop drawings is fundamental: steel structures and prefabricated components, and MEP systems (mechanical, electrical, and plumbing).

Steel Structures and Prefabricated Components

In the case of metal structures, shop drawings are essential for translating the structural design into execution diagrams for the production of individual parts: beams, columns, braces, connection nodes, bolting, and welding. These documents include millimeter measurements, allowed tolerances, identification codes for parts, assembly sequences, and construction details. Without shop drawings, it would be impossible to guarantee interchangeability and precision in industrial prefabrication.

The same applies to prefabricated concrete components, such as facade panels, hollow-core slabs, or stairs. Shop drawings precisely define shape, reinforcements, inserts, and lifting points, allowing for industrialized production with no margin for error and efficient assembly on site.

MEP Systems: Mechanical, Electrical, and Plumbing

MEP systems are among the most complex systems to integrate into a building due to their spatial arrangement and continuous interference with load-bearing structures and architectural elements. Shop drawings in this area serve to define the precise paths of ducts, conduits, pipes, and cables, also indicating supports, brackets, fittings, and inspection points.

In a coordinated MEP project, shop drawings allow for precise verification of clearances, planning of installation sequences, and prevention of geometric or functional conflicts between various systems. Furthermore, these drawings facilitate the preassembly in the workshop of sections of the system, resulting in reduced work on site and greater control over quality.

How to Create Shop Drawings?

Creating shop drawings requires specific technical skills, a deep understanding of the project, and increasingly, the use of advanced digital tools. Depending on the complexity of the work and the level of detail required, the process may vary, but generally follows a series of recurring steps:

1. Analysis of the Executive Project: The first step involves a thorough study of the executive drawings provided by the designer. It is essential to fully understand the geometries, materials, functions, and regulatory constraints of the elements to be realized. In this phase, any technical doubts are clarified, often through dialogue with the design team. Shop drawings do not formally constitute part of the contractual documents, but they must still comply with their contents. In case of discrepancies between the shop drawing and the contractual documents, the latter always prevail;
2. 2D or 3D Modeling: Based on the executive project, the supplier or subcontractor develops a detailed model of the component to be produced or installed. This can occur:
   • with traditional CAD software for 2D representations;
   • or with BIM tools for parametric and informative three-dimensional modeling. In a BIM environment, it is possible to generate shop drawings directly from the IFC model, reducing errors and production times;
3. Insertion of Construction Details and Technical Notes: The drawing is then supplemented with all operational elements: dimensions, materials, sections, part numbers, tolerances, regulatory references, instructions for assembly or installation. Each component must be uniquely identifiable;
4. Verification and Coordination: Once completed, the drawing must be coordinated with other project documents, especially in cases where there are interferences (e.g., between systems and structures). If the project is managed in a BIM environment, clash detection is performed to avoid overlaps between models;
5. Review and Approval: The shop drawing is finally sent for review and approval to the designer, the project manager, and, if required, to the BIM coordinator. Only after formal approval can it be used in production or on site.

In many cases, especially for structural or system components, it is required that the shop drawing be signed or stamped by a qualified technician, confirming professional responsibility for the content of the drawing. The necessity of the stamp may depend on local regulations or contractual requirements.

How to create Shop Drawings

Shop drawings represent much more than simple technical drawings: they are an essential operational tool to ensure quality, efficiency, and coordination throughout the construction process. Whether it involves metal structures, precast components, or complex MEP systems, shop drawings form the operational link between the design idea and on-site execution.

Today, thanks to digital tools, it is possible to generate these documents directly from the BIM model, simply and quickly, even without using a specific BIM authoring software. You can leverage an online drawing creation software to autonomously create plans, sections, and elevations from IFC models. A solution that helps reduce time, eliminate interpretation errors, and maintain full control over graphic documents without relying on complex tools or external figures.

Simplify the management of shop drawings and start creating your documents directly online, practically, precisely, and completely integrated.

FAQ – Shop Drawings

What are shop drawings?

Shop drawings are highly detailed technical documents, created by suppliers, manufacturers, or subcontractors, that translate the execution project into practical instructions for the production and installation of specific components.

Who creates shop drawings?

They are produced by entities such as metalworking companies, prefabricators, installation contractors, MEP subcontractors, and CAD/BIM drafters, either internal or external to the executing companies.

How do they differ from other technical drawings?

Unlike execution drawings, drafted by designers, and as-builts, which document the completed work, shop drawings serve an operational purpose: they guide the manufacturing and assembly of specific elements, providing details on dimensions, materials, assemblies, and interfaces with other systems.

What are shop drawings used for in the construction process?

They ensure that each component is correctly manufactured according to the technical specifications of the project. They promote coordination among disciplines, prevent site interferences, improve execution quality, and reduce time and costs.

Who approves shop drawings?

They must be approved by the designer (architect, engineer), the project manager, and, if present, the BIM coordinator. Only after formal approval can they be used for production or installation.

What information do they contain?

In addition to dimensions and materials, they include tolerances, construction details, codes, assembly diagrams, annotations, and exploded views. They may also propose changes to the initial project (submittals), subject to approval.

In which fields are they used?

They are essential in structural prefabrication (steel, concrete), for the industrialized production of custom components, and for the installation of complex systems like MEP (mechanical, electrical, and plumbing).

How are shop drawings created?

The process involves: analysis of execution drawings, 2D or 3D modeling (CAD/BIM), insertion of technical details, coordination with other models, review, and approval. In many cases, the signature of a qualified technician is also required.