Construction Drawings vs Shop Drawings – Key Differences
Before actual construction begins, a plethora of drawing sets, each having its use, significance, and benefits need to be prepared for successful building completion. These drawing sets are utilized by various stakeholders from preconstruction to actual construction.
Many types of construction drawings are prepared by architects to represent the overall design intent, and at the same time shop drawings are prepared by contractors to illustrate actual field executables. These 2D documents are dominant deliverables in the erection of complex and large-scale structures.
All of these architectural documents and construction site drawings including structural drawings are crucial for execution of different types of construction projects. In this article we’ll look into them and the differences between shop drawings and construction drawings in particular.
Construction drawings vs shop drawings
What are construction drawings or CD sets?
Construction drawings or architectural construction documents, also designated as working drawings and are prepared by architects to visualize architectural elements before actual construction begins. Some construction drawings are also called IFC drawings meaning drawings issued for construction.
Hitech BIM Services undertook a residential building construction project through an architectural engineering firm from the USA. PDF files with markup drawings were converted to an MEP 3D model at LOD 400. The clash-free 3D MEP model fueled a greater detailing level wherein construction documents were extracted from the Revit 3D model. The construction drawings supported the client with accurate fabrication and installation of MEP components. Model-driven drawings reduced onsite rework for the client and increased saving of cost and time.
LOD 400 Modeling in Revit
Revit Drafting Services
Revit Drawings Preparation
What are shop drawings?
Shop drawings are crucial for fabricators to understand component manufacturing and installation during construction. Drafting shop drawings demands a higher level of accuracy, because they carry greater details than an IFC issued for construction.
A BIM consultant firm from Europe approached the team at Hitech BIM Services for an institutional construction project. The team used 2D PDF files and manufacturing information of MEP components to create Revit models and extract MEP shop drawings. The clash-free 3D model with accurate shop drawings helped the client detect and resolve clashes to achieve cost savings and build FTR deliverables.
3D MEP Modeling Revit
MEP 3D Modeling for Plant Room
Key differences between construction drawings and shop drawings
Who is responsible for creating these drawings?
- Construction drawings: Created by architects or engineers at the request of the owner
- Shop drawings: Created by contractors, sub-contractors, manufacturers, or suppliers after a contract has been signed with the owner
When are they created?
- Construction drawings: Before actual construction begins
- Shop drawings: Produced before the start of a construction project from contract drawings and as per project specifications
The purpose of producing these drawings?
Construction drawings
- These drawings contain accurate and detailed specifications of the architectural components reinforced with graphical representations for precise decision-making
- These drawings outline the results or outcome of ongoing work and the final product
- Construction drawings take into consideration the structural use, features, appearance, estimated dimensions, fixtures, materials, equipment performance, and connections to other building components
- Serve as bid drawings for contractors to price out a project, estimate labor, material consumption, and construction costs
Shop drawings
- These sets of drawings interpret the actual design intent, field conditions, and information for fabricators to achieve accurate coordination, fabrication, assembly, and installation
- They ensure all the elements are fabricated and assembled to industry specifications and codes and are also known as prefabrication drawings
- Shop drawings are a greater elaboration of construction drawings as they include detailed components like beams, trusses, etc. to equipment and various layouts
- Every sub-contractor produces its own set of shop drawings for approval
How accurate are these drawings?
Construction drawings
- Since construction drawings are prepared before contractors are hired, they may contain a certain level of errors or ambiguities
- Construction drawings are marked with Verify-in-Field labels to confirm dimensions and actual conditions
- These drawings do not provide specific details but the overall project intent
Shop drawings
- Shop drawings provide accurate dimensions, time stamps, and assembly from a professional engineer
Liabilities and risks during drafting and submission process for these drawings
Construction drawings
- Construction drawings are labeled “Not for Construction” to reduce risks for owners before actual construction begins
- These drawings represent the entire scope of work
- Contractors reference these drawings to budget work and produce change orders if certain aspects are left out
Shop drawings
- Shop drawings reflect the entirety of the contractor’s work scope with in-field conditions and work scope
- These drawings need the construction team for consent or approval
- Shop drawings are referred to many times once the project has commenced
- Drafting these drawings is a step-by-step assembly manual made during the built process
What are the details needed to be included in these drawings?
Construction drawings
- Elevations (Interior and Exterior)
- Plans (Framing, Utility, Roof, Electrical & Lighting)
- Details (Interior and Exterior, and Structural)
- Sections (Buildings and Walls)
- Schedules (Doors and Windows)
- Finishes
- MEP information
Shop drawings
- Component identification with tags and dimensions
- Details about interferences, adjacent components & Tags [Level & Materials ]
- Component coordinates for site surveying and site location
- Location and size of openings (Structural shop drawings containing MEP openings)
- Order and sequence of each shop drawing
- Clearance needs, Assembly details
- Section views
- Notes containing changes, deviations, and dimensions
- Title block containing project name, number, subcontractor names, general notes, abbreviations, and legends
- Initial submission date of drawings and revision dates with descriptions
- Fabrication standards Installation and erection data
Conclusion
Large and complex construction projects begin on paper and need a plethora of drawing sets to achieve project outcomes and perfection. Investing money and time for these minute details fuels the successful completion of a construction project.
Reinforcing new projects with 3D BIM modeling plays a vital role in augmenting the accuracy, reliability, and quality of construction and shop drawings. 3D Model-extracted drawing sets reduce errors, ambiguities, and delays and illustrate information completeness for architects and contractors.
About the Author:
