Precision is crucial in the construction industry. MEP shop drawings are highly detailed documents which are used for guiding fabrication and installation of the systems. MEP shop drawings differ from design drawings as they are not supposed to present the design intent of the project, but rather the instructions for fabrication and installation of the building systems.
The quality of MEP shop drawings directly affects the project success rate. Mistakes in the shop drawings cause project rework, delays, additional costs and safety risks. A quality assurance (QA) process of the shop drawings is crucial for reducing the number of requests for information, minimizing site changes, speeding up the approvals and achieving better cost control and safety outcomes.
This article presents a practical QA checklist for the MEP shop drawings with useful tips which can help your team reduce rework, improve coordination and get quick approvals. Whether you are an in-house team or using specialized shop drawing services, this guide is for you!
Quick Primer on MEP Shop Drawings and QA
MEP shop drawings are very detailed documents which are produced by contractors, fabricators or specialized shop drawing services. MEP shop drawings present the details of the installation of the MEP systems. They include dimensions, equipment schedule, routing, type of connections, details for fabrication and on-site installation.
Shop drawing services are not just about producing drawings, but also ensuring that the designs are manufacturable, installable and coordinated with other building systems. Good MEP shop drawings guarantee a smooth process of approving them by the consultant or the client and help to avoid conflicts during construction.
Quality assurance is crucial in this context, as MEP systems take quite a lot of costs of the building (about 40-60% of the total project cost) and are among the most complex in terms of coordination. The key risk areas in MEP systems include clashes with structure or architecture, manufacturability (the systems which cannot be fabricated and installed), non-compliance with codes, missing or incorrect dimensions. A single mistake can cause huge costs and delays. Therefore, QA is not only a final step of checking drawings, but a process of checks and sign-offs which help to eliminate the issues early in the project life cycle.
Who Performs QA and When
Quality assurance of the shop drawings is a joint effort of the multiple parties. First of all, detailers and drafters perform self-check, then BIM coordinators are responsible for clashes detection and model federation. MEP engineers ensure the compliance with design intent and codes and the QC managers perform systematic quality control. In turn, contractors and fabricators review drawings for constructability and manufacturability, whereas the client and consultant reviewers give final approval for construction.
QA should be performed at specific points in the workflow:
• Initial Drafting: The detailer checks basic drawing standards and dimensional accuracy.
• Internal QA: A full QA checklist is applied to the drawings to identify errors.
• BIM Clash Detection: Automation tools are used to detect clashes between architectural, structural and other MEP services.
• Pre-Submission Review: Multi-disciplinary team review the drawings to check coordination and compliance before submitting them to the client or consultant.
• Post-Approval Revision Checks: Any changes performed after the approval are re-checked to make sure they do not introduce new errors.
Core QA Checklist: What to Check
Below there is the checklist with the main points to review in the MEP shop drawings. It includes tips on why each point is important and how to check it properly.
General Drawing Standards
Check title blocks, revision history, drawing numbering, scale, north arrow, units, legends and notes. These are the fundamental elements which guarantee clear communication.
Why it matters: Missing or inconsistent information can result in confusion and delays.
Tip: Use a company-standard template for consistency. Automatically check title blocks using your drafting software.
Coordination and Clashes
Detect clashes with architectural, structural and other MEP services. Check that the coordination spaces and clearances are sufficient for installation and maintenance. Clash resolution is the major issue in MEP coordination. Clashes can be divided into hard clashes (intersection), soft clashes (lack of clearances) and constructability clashes (sequencing).
Why it matters: Unresolved clashes are a main source of on-site rework and cost overruns.
Tip: Use automation tools for clash report generation. Add visual clash checks in congested zones such as plant rooms, risers and corridors. Start with the high risk clashes (structural vs MEP).
Dimensional Accuracy and Levels
Ensure that there are proper dimensions, offsets, clearances to structure, ceiling height, slab level and datums are accurate. This is the basis of a good drawing.
Why it matters: Even small mistakes can result in fit issues during the fabrication and installation.
Tip: Make sure the drawings contain annotations of the critical dimensions, which are needed for fabrication. Do not use vague notes such as "verify on site". If some kind of field verification is required, make sure that it is clearly described.
Equipment and Panel Schedules
Check correct equipment tags, model numbers, sizes, capacity, orientation, access and clearances, maintenance spaces. The information in the drawings should correspond to the project specifications and equipment submittals.
Why it matters: Incorrect equipment information can cause procurement of wrong equipment, its wrong installation and failure.
Tip: Cross-check Bill of Materials (BOM) and schedules with the project specifications and manufacturer's datasheets. Early involve procurement to flag long-lead items.
Ductwork, Piping and Cable Routing Details
Check correct sizes, material specification, slope or pitch for drainage, supports and hangers (with proper spacing), isolation and valve locations, access panels.
Why it matters: Wrong routing, materials or hangers cause system failures, leaks and other safety issues.
Tip: Show alternative routing options and types of hangers directly on the drawings. Coordinate routing, taking into consideration hierarchy of systems (first HVAC ducts, then electrical trays, then fire network and plumbing pipes).
Fabrication and Installation Details
Check shop-specific details such as splices, connection type, welds, fabrication tolerances, hanger/shop fit details. Such information is crucial for the prefabrication and modular construction.
Why it matters: These details bridge the design and fabrication stages. Correct instructions prevent on-site guessing and mistakes.
Tip: Add shop notes and the fabrication sign-off block to check that the drawings were reviewed by the fabrication team.
Electrical Specifics
Check conduit runs, cable tray routing, cable types, segregation of different voltage levels, fault current and short circuit ratings, panel schedules, earthing or grounding details.
Why it matters: Not following segregation rules or wrong sizes result in serious electrical hazard and system malfunction.
Tip: Check cable fill, derating and conformity with local codes. Make sure there is enough space in cable trays for additions.
Mechanical Specifics
Check pump schedules, valve tagging, balancing valves, HVAC terminal unit tagging, airflow direction, test or commissioning ports.
Why it matters: Proper identification and layout of the equipment is essential for balancing, testing and further maintenance.
Tip: Include commissioning access and balancing information in the drawings. Make sure there are convenient access points for valves and panels.
Codes, Standards and Specifications
Make sure there is compliance with local building codes, HVAC, electrical, plumbing standards, fire safety, acoustic and energy requirements.
Why it matters: Non-conformity leads to rejection of the drawings, project delays and potential legal liabilities. According to researches about 17-27% of shop drawings are rejected due to non-conformity.
Tip: Reference the clause from the code on the drawing or QA checklist. Stay informed about amendments of the national codes in the local jurisdiction.
Manufacturability and Procurement Checks
Make sure that the drawings specify available materials and equipment, lead times, prefabrication possibility and weight-lifting limitations.
Why it matters: Drawings which specify the materials or equipment which cannot be manufactured are useless and lead to serious delays.
Tip: Early involve the procurement team to coordinate materials and flag long-lead items. For heavy equipment include weight and lifting points in the drawings.
Quality Annotations and QA Sign-offs
Check QA stamp, approval block, comments of the reviewers, open items list, revision control.
Why it matters: This procedure guarantees accountability and that all the issues were addressed before the drawings are approved for construction. It helps to avoid the work with unapproved drawings.
Tip: Require sign-off from the discipline lead and BIM coordinator before submission. Use the consistent revision numbering and cloud all changes.
Safety and Maintainability
Make sure there is no problem with access for maintenance, safety clearances, safe routing of services (for instance, no overhead electrical lines in proximity of water pipes) and labeling of dangerous systems.
Reason: Drawings not taking into account safety and maintainability create dangerous working environment and further operational problems. Safety during design is the highest priority.
Recommendation: Mark out maintenance paths and service points in drawings. Make sure clearances comply with equipment access requirements provided by manufacturer and codes.
Tools and Methods to Improve QA
Modern MEP coordination and QA process involve lots of technology. The best tool for this purpose is Building Information Modeling (BIM). BIM allows for clash detection automation and model federation, when all models from all disciplines get combined in order to identify conflicts in digital environment. Automated rule-checkers can be used to verify compliance with drawing standards and project requirements. When using standard CAD standards managers, checklists and templates mistakes are reduced and efficiency is increased. With virtual walkthrough and photorealistic renderings team members can easily see complicated space and potential problems which can hardly be seen on the drawings.
Main recommendations for successful implementation of these tools and methods:
Peer Review: Create a procedure for peer review of drawings performed by an experienced colleague.
Integrated QA/QC Checklist: Integrate your QA checklist into drawing release process.
Issue-Tracking Platforms: Use project management software such as BIM 360 or Procore for tracking of clashes, comments and approval workflow.
Periodic Audits: Perform regular audits of a random sample of drawings.
Most Common QA Failures and Their Prevention
There are some recurring problems which lead to poor quality of MEP shop drawings. Knowing about these mistakes is the first step to prevent them.
Failure #1: Missing or Incorrect Dimensions. One of the most widespread and serious mistakes caused usually by hurry or absence of coordination.
Prevention: Use standard templates and enforce mandatory QA process in order to verify all crucial dimensions.
Failure #2: Clash Not Detected. Noticing clashes with structure and other services is a problem which arises because of dependence on manual checking only.
Prevention: Perform automated clash detection and hold cross-discipline review sessions for physical walkthrough of the model.
Failure #3: Incorrect Size or Tag of Equipment. It can occur due to change of specifications or absence of cross-check of drawings with actual material submittals.
Prevention: Work with the procurement team from the beginning and review drawings in accordance with current BOM and approved submittal list.
Failure #4: Ambiguous Notes. Ambiguous or contradictory notes cause field misunderstanding and mistakes.
Prevention: Use clear, concise and explicit language in drawing notes.
Failure #5: Non-Compliance with Codes. Such failure is usually the result of using outdated data or lack of understanding of local code amendments.
Prevention: Have your drawings reviewed by a licensed MEP engineer who is aware of the local codes.
Example of Quick QA Process
Effective QA process should include certain steps in particular order. Below there is an example of quick QA process.
Drafting and Modeling: Detailer creates the initial shop drawing and model.
Internal QA: Detailer performs self-inspection with the help of QA checklist of the company.
BIM Clash Run: The BIM coordinator runs automated clash report and distributes results among team members.
Discipline Lead Sign-Off: The lead MEP engineer verifies technical correctness of the drawings.
Coordination Review: Hold formal meeting with all stakeholders (fabricators, other trades) for coordinated model review.
Client/Consultant Submission: Submit package for final review.
Fabrication Release: Release of drawing for fabrication after approval by the client/consultant.
Example: During BIM clash run for a commercial building, the system has detected the clash of new HVAC duct with structural support beam. It would have caused cutting of this beam on the field if it had not been found beforehand. In this case, MEP engineers have worked with structural engineers in order to reroute the duct before any actions and saved lots of money and project time.
Conclusion
A good QA process for MEP shop drawings is an investment into your project success. Implementation of a systematic checklist, BIM tools and cooperation culture helps teams to significantly reduce amount of RFIs, rework and site changes. It guarantees fast approvals, good safety results and control over project costs.
Use comprehensive QA checklist, perform BIM coordination and, if your project requires, use shop drawing services for complex MEP systems.
Investments into quality in advance guarantee your time and cost savings.
frequently Asked Questions
What does MEP shop drawing QA checklist include?
It should include checks for drawing standards and title blocks, dimensional correctness and level, equipment and panel schedules, coordination with other services and fabrication details, codes and specifications compliance, QA sign-offs, provision for safety and maintainability.
Who should sign off on MEP shop drawing QA?
It should include multi-level sign-off by discipline lead (MEP engineer), BIM or coordinating engineer, QC manager and, if necessary, client or consultant.
How do BIM tools improve MEP shop drawing QA?
They help to detect clashes automatically and perform model federation, which allows to find all conflicts between architecture, structure and MEP systems in digital environment.
How can we reduce rework from shop drawing issues?
We should use standard templates, hold early coordination meetings, implement mandatory internal QA process, perform automated checks and work with procurement and fabrication team at early stages of project. It is important to implement multi-level QA process.
What are the most common shop drawing mistakes that lead to delay?
The most common mistakes are missing or incorrect dimensions, not resolved clashes with structure or other services, incorrect equipment tags or sizes, incorrect fabrication details and non-conformance with building codes.
How long should QA take before submission?
The duration of QA depends on the size and complexity of project. For usual package spend 48-72 hours for internal QA and clash runs. More complex systems and multi-discipline coordination will take additional time.
Need Help with Your MEP Shop Drawings?
At CAD Drafting Services we provide you with high-quality MEP shop drawings and BIM coordination services. Our specialists use BIM technologies to provide you with accurate, coordinated and code-compliant drawings and to help you to reduce rework, avoid delays and gain fast project approvals.