In construction projects, having the right set of drawings is crucial for success. But many people get confused between tender drawings and shop drawings. What are they exactly? And why does it matter? In this post, we’ll dive deep into both types of drawings, explaining what they are, how they differ, and why they are important for ensuring your project stays on track. Whether you’re a contractor, architect, or engineer, understanding these differences can help you avoid costly mistakes and delays.
What Are Tender Drawings?
Tender drawings are the initial set of plans prepared by architects or engineers to outline the scope of a project. These drawings are submitted during the bidding process to help potential contractors understand what the project entails.
Key Points of Tender Drawings:
- Purpose: Tender drawings define the general design and specifications of a project.
- Prepared By: Usually created by the project’s architect or designer.
- Details Included: Layouts, elevations, material specifications, and design intent.
- Accuracy Level: More general, focusing on the overall vision rather than specific details.
- When Used: Tender drawings are submitted during the tendering process, helping contractors understand the project’s scope for accurate bidding.
Do You Know?
Tender drawings are not final. Contractors often submit questions or requests for clarification based on these drawings, which can lead to adjustments before the contract is finalized.
What Are Shop Drawings?
Shop drawings are highly detailed plans that come into play once the tender is won. These drawings are produced by contractors, suppliers, or fabricators to show how specific elements will be manufactured, assembled, or installed.
Key Points of Shop Drawings:
- Purpose: They provide detailed instructions for fabrication and assembly of components.
- Prepared By: Usually created by the contractor, fabricator, or supplier.
- Details Included: Measurements, dimensions, material specifications, and fabrication methods.
- Accuracy Level: Highly precise, focusing on construction-level details.
- When Used: Shop drawings are prepared after the tender is awarded and are used during the construction phase.
Do You Know?
Shop drawings can vary slightly from tender drawings due to real-world considerations like material availability or site conditions. Any changes made in shop drawings need approval from the project’s architect or engineer.
How Are Tender Drawings and Shop Drawings Different?
While both types of drawings are crucial for the construction process, they serve very different purposes. Let’s break down the key differences between the two:
1. Purpose
- Tender Drawings: Provide an overview of the project’s scope and are used for bidding.
- Shop Drawings: Offer detailed instructions for fabrication and assembly.
2. Level of Detail
- Tender Drawings: Tend to be broad, covering general aspects of the design and layout.
- Shop Drawings: Are very detailed, often including exact dimensions, materials, and construction methods.
3. Timing
- Tender Drawings: Created before a contractor is chosen, during the bidding phase.
- Shop Drawings: Created after the contract is awarded, during the construction phase.
4. Prepared By
- Tender Drawings: Usually prepared by architects or engineers.
- Shop Drawings: Usually prepared by contractors, fabricators, or suppliers.
Do You Know?
Contractors often use shop drawings to coordinate between various teams, ensuring that everyone is on the same page during the construction process.
| Criteria | Tender Drawings | Shop Drawings |
|---|---|---|
| Purpose | Outline the general design and project scope for bidding. | Provide detailed instructions for fabrication and installation. |
| Prepared By | Architect or Engineer | Contractor, Supplier, or Fabricator |
| Timing | Created during the tender or bidding phase | Created after the contract is awarded, during the construction phase |
| Level of Detail | General, broad design and specifications | Highly detailed with exact dimensions, materials, and methods |
| Accuracy Level | More general and focuses on the design intent | Very precise and focuses on construction-level details |
| When Used | During the bidding process | During the fabrication and construction phase |
| Details Included | Layouts, elevations, material specifications, and design intent | Specific measurements, material specifications, fabrication methods |
| Approval Needed | Approval by the client before finalizing | Reviewed and approved by the architect or engineer before fabrication/installation |
| Revisions | Can be revised based on contractor queries before finalization | Must be revised and resubmitted if not approved |
| Conflict Resolution | Can be adjusted based on contractor feedback | Discrepancies resolved through the RFI process |
| Importance | Helps contractors understand project scope for accurate bidding | Ensures components are built and installed correctly |
| Focus | Vision and design of the project | Execution and technical details of the project |
| Examples of Use | Building layouts, elevations, general material selections | Fabrication drawings, installation methods, joint connections |
| Changes Allowed? | Can be adjusted before final approval | Any changes must be approved by the architect or engineer |
| Legal Standing | Forms part of the contract documents | Acts as a guide for construction but must align with tender drawings |
Why Are Tender and Shop Drawings Important?
Both tender and shop drawings play vital roles in the success of a construction project. Without tender drawings, contractors wouldn’t have enough information to submit an accurate bid. And without shop drawings, it would be difficult to fabricate or install components according to the project’s requirements.
Top Facts:
- Tender drawings set the stage for project scope and cost estimates.
- Shop drawings ensure that the project is built according to the design intent and specifications.
- Misunderstandings between tender and shop drawings can lead to costly delays and errors.
- Shop drawings often include more technical details like joint connections, fastening methods, and welding procedures.
- Both sets of drawings need approval before construction begins to avoid miscommunication and mistakes.
Do Tender Drawings and Shop Drawings Ever Overlap?
In some cases, yes. However, while tender drawings give a broad understanding of what needs to be built, shop drawings go into the nitty-gritty details of how it will be built. For example, while a tender drawing might show the overall layout of a building’s façade, shop drawings would detail how each panel is installed, including connections and materials.
What Happens If There’s a Conflict Between Tender and Shop Drawings?
Conflicts between tender and shop drawings can occur, especially if details were missed during the initial tender phase. When this happens, the contractor needs to seek clarification from the architect or engineer. Adjustments are made through a Request for Information (RFI) process, which helps resolve discrepancies.
How Are Tender Drawings Reviewed?
Tender drawings undergo multiple rounds of review by different stakeholders before being finalized. Typically, the architect submits the drawings to the client, who reviews them for approval. After client approval, these drawings are issued to contractors for bidding.
How Are Shop Drawings Reviewed?
Shop drawings go through a more rigorous approval process since they include detailed manufacturing or installation instructions. The contractor submits the shop drawings to the architect or engineer, who reviews them for accuracy and compliance with the tender drawings. Once approved, they can proceed with fabrication or installation.
What Happens If Shop Drawings Aren’t Approved?
If shop drawings are not approved, the contractor must revise and resubmit them. This process can take time, and delays in approval can lead to project delays. Therefore, it’s essential to ensure that shop drawings are as accurate as possible before submission.
FAQs
1. What are tender drawings used for?
Tender drawings are used to define the scope of a project during the bidding process.
2. Who prepares shop drawings?
Shop drawings are prepared by contractors, suppliers, or fabricators.
3. What’s the main difference between tender drawings and shop drawings?
Tender drawings are for bidding purposes and provide a general project overview, while shop drawings are detailed and used for fabrication and construction.
4. Can shop drawings change tender drawings?
Yes, but any changes must be approved by the project’s architect or engineer.
5. Why are shop drawings important?
Shop drawings provide the detailed instructions necessary to fabricate and install components correctly.
6. When are shop drawings created?
Shop drawings are created after the tender has been won and during the construction phase.
7. What if tender drawings don’t match shop drawings?
Any conflicts must be resolved through an RFI process to ensure that the project is completed accurately.
8. Can tender drawings be revised?
Yes, tender drawings can be adjusted based on contractor feedback before finalizing the project scope.
9. Do tender drawings include dimensions?
Yes, but they are generally less detailed than those in shop drawings.
10. What happens if shop drawings are not approved?
The contractor must revise and resubmit the shop drawings for approval.
Conclusion
In the world of construction, both tender and shop drawings are indispensable. While tender drawings give an overview of the project for bidding, shop drawings ensure precise execution during the construction phase. Understanding the differences between these two types of drawings is key to keeping a project on schedule and within budget. Make sure you have a clear plan for handling both sets of drawings to avoid costly delays and errors.
Key Takeaways
- Tender drawings outline the general design and specifications for a project.
- Shop drawings provide detailed instructions for fabrication and installation.
- Both drawings are crucial for ensuring a successful construction project.
- Any discrepancies between tender and shop drawings should be resolved through the RFI process.
