Tender drawings are a critical part of the construction process, but many people are unsure how they differ from other types of trade drawings. These drawings have a specific purpose, mainly helping companies bid for construction projects. But, how exactly are they different from shop drawings or as-built drawings? This article will explore the key distinctions, ensuring you understand the purpose and importance of tender drawings in construction.
What Are Tender Drawings?
Tender drawings are the technical plans used during the bidding phase of a project. They serve as the baseline for contractors to estimate costs, labor, and materials. These drawings are essential for anyone submitting a tender (a formal offer) in construction projects.
Tender drawings are often incomplete or generalized. This happens because they are primarily meant for pricing and not for direct construction. Contractors analyze these drawings to prepare their bids, including costs and timelines.
Key Points About Tender Drawings:
- Purpose: Tender drawings are designed for competitive bidding.
- Detail Level: They include enough information for cost estimation but not intricate details like exact dimensions for building.
- Accuracy: While relatively accurate, these drawings are sometimes revised during the project to include more details.
How Are Trade Drawings Different From Tender Drawings?
Tender drawings are primarily used for cost estimation, while trade drawings serve a more specialized purpose. Each type of trade drawing focuses on a particular aspect of the construction project, such as plumbing, electrical systems, or structural components.
Trade Drawings Include:
- Shop Drawings: Detailed versions of tender drawings, used for actual construction.
- As-built Drawings: These show what was actually built, often including modifications that occurred during construction.
Trade drawings are far more detailed than tender drawings. They include exact measurements and specifications needed to carry out construction work accurately.
Why Are Trade Drawings Important?
Trade drawings guide contractors through the specifics of construction. Each drawing provides a clear set of instructions for various teams like electricians, plumbers, or structural engineers. Unlike tender drawings, trade drawings don’t focus on pricing but on ensuring the project is executed correctly.
Key Differences:
- Focus: Tender drawings are for cost estimation, trade drawings are for construction execution.
- Detail: Trade drawings are more detailed and precise.
- Usage Stage: Tender drawings are used during bidding, while trade drawings come into play during the construction phase.
Why Are Tender Drawings Less Detailed?
Tender drawings tend to be less detailed than other trade drawings because they are created during the project’s early stages. At this point, not all design aspects are finalized. Therefore, these drawings present an outline or rough concept of the project, allowing contractors to give a ballpark estimate of costs.
Do You Know?
Tender drawings might lack detail, but they still play a crucial role in deciding who wins the project bid. Inaccuracies in these drawings can lead to costly miscalculations later!
How Do Tender Drawings Help in Cost Estimation?
Tender drawings are the foundation for the bidding process. Contractors use these documents to estimate:
- Material Costs
- Labor Expenses
- Project Timelines
For example, a contractor bidding on a bridge construction project will use tender drawings to figure out how much steel, concrete, and labor are required. However, without the fine details available in shop drawings, they’ll need to make educated guesses for some aspects of the project.
Common Mistakes in Tender Drawings:
- Inaccurate Dimensions: Missing details can lead to wrong cost estimates.
- Omissions: Sometimes, crucial elements are left out, which leads to confusion later in the project.
What Are Shop Drawings?
Shop drawings take over where tender drawings leave off. These drawings are created after the bid is won and provide the exact specifications needed to construct the building or structure. Unlike tender drawings, shop drawings are:
- Highly Detailed: Include material specifics, dimensions, and placement.
- Created by Contractors: These drawings are developed by the contractors for specific trades like steelwork, HVAC systems, or electrical wiring.
How Are Shop Drawings Used?
Contractors use shop drawings as a step-by-step guide during construction. They ensure that each element is built correctly according to the design specifications. Shop drawings are also shared with engineers and architects for approval before construction begins.
Comparison:
- Tender Drawings: Generalized and for pricing.
- Shop Drawings: Specific and for construction.
What Are As-built Drawings?
As-built drawings capture the project as it was constructed. They differ from both tender and shop drawings in that they reflect all changes made during the construction process. If a contractor deviates from the original plans due to site conditions or client requests, those modifications are documented in the as-built drawings.
Importance of As-built Drawings:
- Documentation: They act as a record of what was actually built.
- Maintenance: Useful for future repairs and renovations.
Which Drawings Come First: Tender or Shop Drawings?
Tender drawings always come first, as they serve as the foundation for initial project planning and cost estimation. Shop drawings are produced after the tender is awarded and the construction phase is ready to begin. Without tender drawings, there wouldn’t be a competitive bidding process. However, without shop drawings, construction couldn’t proceed with the necessary precision.
Do You Know?
Tender drawings often exclude minor details, which means contractors must rely on experience to fill in the gaps. This is why larger projects usually prefer experienced contractors who can work with less detailed plans.
What Are the Do’s and Don’ts of Working with Tender Drawings?
Do’s:
- Review Carefully: Make sure all aspects of the drawing are reviewed for accuracy.
- Seek Clarifications: If something is unclear, consult with the designer or client.
- Estimate Conservatively: It’s better to overestimate costs than to submit a low bid and face budget issues later.
Don’ts:
- Don’t Assume Details: If details are missing, don’t guess—ask for clarification.
- Don’t Rush the Review: Taking your time can save headaches down the road.
- Don’t Ignore Changes: If the drawings are updated, ensure your bid reflects these changes.
FAQs:
1. What are tender drawings?
Tender drawings are used to provide an estimate for the cost of a project, including labor and materials.
2. Are tender drawings the same as shop drawings?
No, tender drawings are for cost estimation, while shop drawings provide the specific details needed for construction.
3. Can tender drawings change?
Yes, tender drawings can be revised before and during construction as more details become available.
4. Why are tender drawings less detailed?
Tender drawings are less detailed because they are created during the early stages of project planning.
5. Who creates tender drawings?
Tender drawings are usually prepared by architects or engineers, but they are intended for contractors to use in preparing bids.
6. What are trade drawings?
Trade drawings are specific to different disciplines like electrical, plumbing, or structural work. They are used to execute the actual construction.
7. Do contractors use tender drawings during construction?
No, contractors typically use shop drawings for construction. Tender drawings are only for the bidding phase.
8. How do tender drawings help in cost estimation?
Tender drawings outline the project scope, allowing contractors to estimate material, labor, and other costs.
9. What happens if tender drawings are inaccurate?
Inaccurate tender drawings can lead to incorrect bids, which may cause financial issues during the project.
10. Are as-built drawings more detailed than tender drawings?
Yes, as-built drawings document every change made during construction, making them much more detailed than tender drawings.
Conclusion:
Tender drawings play an essential role in the construction industry, serving as the foundation for project bids. While less detailed than shop or as-built drawings, they allow contractors to estimate costs and compete for projects. Understanding the differences between tender and other types of drawings can help streamline project planning and avoid costly errors. Always review tender drawings carefully and seek clarifications where necessary.
Key Takeaways:
- Tender drawings are crucial for bidding but lack the detail needed for actual construction.
- Trade drawings like shop and as-built drawings offer more precision and are used during the construction phase.
- A thorough review of tender drawings helps prevent cost estimation mistakes.