Construction projects experience delays, costly rework, and budget overruns as a result of the improper quality of shop drawings. Imagine how much time and money you waste because your installation teams arrive on site and find out that the ducts clash with the structure or the electrical conduits pass right through the plumbing stack.

MEP shop drawings represent the detailed and dimensioned drawings that guide the installation and fabrication of all mechanical, electrical, and plumbing systems . These drawings are usually prepared either by contractors/subcontractors or by specialized shop drawing providers. A quality checklist is one of the important tools to make sure that every component of the system is installed properly without any errors.

In this article, we are going to discuss MEP shop drawing checklist which includes documentation review, technical checklist for all systems, clash detection and coordination, and handover deliverables.

Importance of QA/QC Process in MEP Shop Drawings

As a result of lack of QA/QC process in MEP shop drawings, a project experiences delays and rework costs that occur due to the clashes during installation process. A survey on construction project delays has found that rework due to errors is one of the factors that caused delays in the submittal and approval process . There is even a case study in which strict quality control during the process of shop drawing resulted in reducing the amount of rework by 30% .

However, a proper QA/QC process gives numerous benefits, including coordinated drawings, which is crucial for accurate prefabrication. Since all components are made based on precise drawings, there is less probability of making an error. Also, fewer RFIs from the field, proper clearance during installation process, and easier project completion can be listed among other benefits.

Who is Responsible in the Workflow

Quality assurance and control is the responsibility of all project participants. There are certain handovers that require the QA/QC of drawings at specific points of the process. The designer of the original concept is responsible for reviewing drawings for the general conformity to the contract documents . At the same time, the general contractor (GC) coordinates and manages the submittal process.

The MEP subcontractor and his/her specialist in charge of shop drawings (BIM manager or a shop drawing coordinator) is responsible for preparation and internal QA/QC for technical accuracy and coordination prior to the submittal.

There should be quality checks at the stage when design drawings are converted to shop drawings, when the shop drawings are completed for fabrication, and again prior to the installation to ensure that all field conditions are accurate.

QA/QC Checklist: General Documentation and Administrative Items

  • It is necessary to carry out the review of documentation prior to performing technical QA/QC for all systems.
  • Project Information: Make sure that all sheets contain the project name, drawing number, revision number, and issue date. This is one of the basic checks for verification of all teams’ work .
  • Revision History: Check whether there is a block with a revision history. All changes in revisions should be “clouded” and marked by the revision triangle .
  • Sheet Index and Drawing List: Verify the completeness of the drawing set, presence of sheet index and the description of the content of the drawing in its title.
  • Specification and Scope Reference: Refer the drawings to relevant specification sections. The drawings should refer to the contract documents, general details, and RFIs.
  • Approval Status and Signature Block: It is necessary to make sure that the drawing has the correct status (e.g. “Approved”, “Approved as Noted”, “Revise and Resubmit”), approved by the responsible member of the designer team .

Cross-reference of Materials and Equipment Submittals: It is crucial to verify that all materials and equipment used in the drawing were already approved. It is not recommended to approve drawings if the submittal of some materials related to the drawing is still pending . Changes in the material submittal can affect the shop drawings drastically.

Tolerances, Coordination Zones, and Site Constraints: Include notes regarding installation tolerances, site constraints, and coordination zones.

Technical Checklist: Mechanical Systems

  • Reviewing the mechanical system drawings is crucial for proper performance, accessibility, and coordination of all equipment.
  • Equipment Schedules: Verify that all mechanical equipment (air handling units, fan coil units, chillers, pumps) have proper model numbers, capacities, power, weight, and clearances. They should conform to the approved submittals .
  • Duct Routing and Sizes: Make sure that all ducts are sized properly based on friction and velocity calculations. Verify that there are proper transition pieces and access doors at the coils, dampers, and filters.
  • Locations of AHU and FCU, Access: Make sure that the location of equipment provides necessary access to AHU and FCU for maintenance and filters changing. Coordinate the information about equipment with the structural drawings.
  • Piping Sizes, Slope, Insulation and Hanger Spacing: Make sure that all piping systems are designed with the appropriate slope for draining purposes, proper insulation, and hangers spacing. It should be done according to mechanical codes.
  • Hydronic System: Verify all parameters including pump curves, delta-T (temperature difference), size and location of the expansion tank and balancing valves.
  • Exhaust and Fresh-Air Outlets: Verify termination details of the exhaust system and fresh air intake to comply with code requirements and maintain proper distance.

One of the most frequent mistakes during the design of the mechanical system is that the location of a large air handler is chosen so that there is no access to its panels because of the presence of some other equipment (e.g. structural columns). The checklist catches this issue at the early stage, comparing the clearance requirement with the architectural/structural drawings.

Technical Checklist: Electrical Systems

  • Precise electrical drawings review prevents overload of circuits, makes conditions safe and avoids last-minute changes.
  • Power Distribution System: Compare the single-line diagram with feeders’ sizes and setting of breakers to check the correctness of sequence and protection.
  • Panel Schedules: Check the load, spare capacity, and labeling in panel schedules. Make sure that the distribution of the circuits is balanced and there are no overloads on any particular phase .
  • Conduits and Cable Trays Routing: Verify conduit fill calculations, bend radius, and clearance between different systems. It is necessary to verify the routing of cable trays and pathways of the low-voltage system.
  • Locations and Access to Equipment: Verify the locations of all equipment (switchgear, panels, transformers etc.) and make sure that there is access to equipment and proper grounding/earthing details.
  • Lighting Layouts and Lighting Controls: Verify lighting layouts and make sure that there are enough lumens. Coordinate lighting controls with BAS (building automation system).

Coordination with other Trades: Make sure that the suggested pathway for the conduits and cable trays does not overlap with structural grid, HVAC ducts and plumbing pipes. As an example, the single-line verification can include tracing the path of the high-capacity feeder from the main switchboard to the rooftop AHU.

Technical Checklist: Plumbing and Fire Protection

Review of the plumbing and fire protection drawings is performed for compliance with code requirements, system integrity and coordination with other trades.

Plumbing Checks:

  • Count and locations of the fixtures: Count of the fixture units and their locations on the plumbing drawing should match architectural plans.
  • Sanitary and Storm Drainage: Verify that drainage pipe has proper slope and cleanout for maintenance.
  • Water supply: Verify that the drawings contain the information about pressure, correct location of backflow preventer and isolation valves.
  • Materials, insulation and thermal expansion: Verify that all materials, insulation types and locations of thermal expansion joints are according to the specifications.

Fire protection Checks:

  • Hydraulic calculation and risers’ diagram: Verify hydraulic calculations and risers’ diagram.
  • Sprinkler head type, spacing and obstructions: Verify that sprinklers have proper type, spacing according to the code requirements, and are not obstructed (by light fixtures or beams).
  • Locations of Standpipe and Control Valves, Signage: Verify that there are standpipe outlets, control valves (like FDC connection) and all necessary signage.
  • Coordination with Structural and Ceiling Systems: Make sure that all fire protection components, especially risers and sprinkler drops, coordinate with the structural and ceiling grid systems.
  • It is important to comply with all the local codes and AHJ requirements, which are the final word in the approval of the systems.

Clash Detection and Coordination

Clash detection is where QA/QC turns into a tool for site issue prevention. Clash detection in BIM is vastly superior to 2D overlay comparison. In 3D you can federate a model and perform an interference check to find out whether, for instance, a duct hits a steel beam .

Clashes need to be identified, assigned to the right trade, resolved in the model, and tested again to make sure that the problem is resolved. An effectively coordinated model or mark-up package proves it. Advanced teams even apply augmented/virtual reality technology to resolve the issue before installation saving tens of thousands in rework costs .

Review, Approval and Handover Deliverables

The last stage of QA/QC is formal handover of the package as-built documentation which will serve as a reference point for future maintenance and upgrades. The final deliverables include:

  • Approved shop drawings and as-builts – As-builts (record drawings that capture all the field changes) are often required for project closeout .
  • BIM Model – The coordinated BIM model usually constitutes the most valuable as-built deliverable.
  • Submittals and vendor data – The final list of all approved submittals (material submittals, product data sheets and test certificates) .
  • Version control – It is recommended to use archiving practices like adding a suffix to name of the final as-built set so that the future teams know the version they are working with.

Common Issues, Quick Fixes and Best Practices

Typical MEP shop drawings’ problems include no dimensions, incorrect models of equipment used in the drawing and inaccessible route planning because of poor coordination. Those issues can be prevented by the use of some quick fixes like creating drawing templates, building a library of accurate CAD/BIM families and embedding the QA/QC checklist from the very beginning. Good practices also include holding coordination meetings early on with all trades, using standard file naming convention and detailed drawings with focus on prefabrication.

Why Professional Shop Drawing Services?

Using a professional shop drawing service can be a smart step towards reducing risks and improving quality of your drawings. Professional services provide special speed, consistency and in-depth knowledge of QA/QC processes. They handle drafting, BIM coordination, clash detection and submittal process allowing your in-house team to concentrate on managing the site. Professional shop drawing services provide prefabrication-ready drawings that minimize RFIs and installation problems. Their expertise allows making sure that your drawings are not only coordinated but submitted and approved without any further back-and-forth.

Conclusion

An effective MEP shop drawings QA/QC checklist is a vital tool for any construction project. It helps reduce the risk of reworks and schedule delays associated with incorrect drawings through systematic verification of documentation and technical system details and their coordination between the trades.

Ready to achieve high quality, clarity and coordination of your MEP drawings? Get help from professionals.

[CTA] Contact Camellia Buildtech to get a free consultation, download a sample QA/QC checklist, or ask for quote of our specialized shop drawing services.

Frequently Asked Questions

  1. What is included in an MEP shop drawing QA/QC checklist?

The standard checklist includes: review of administrative documents (revision status, approvals), technical checks for mechanical (HVAC, piping), electrical (power, lighting) systems, plumbing and fire protection as well as BIM/clash coordination check and concludes with final approval sign-off.

  1. Who needs to approve MEP shop drawings before fabrication?

The approval of drawings comes from project design consultant or engineer of record who reviews drawings for general compliance with the contract documents . The MEP subcontractor’s QA team and general contractor sign off as well and sometimes final approval rights go to client or AHJ.

  1. How do I integrate BIM clash detection into my QA/QC process?

At first you need to federate all trade models into one view. Perform clash test (e.g. interference test) to identify clashes. Categorize and assign each clash to the responsible party. Resolve the issues in the model. Re-run the tests to verify that clashes are resolved and sign-off the coordinated model .

  1. How early should shop drawing QA/QC begin?

QA/QC process should start immediately after IFC (release for shop drawing documentation). For high-risk systems it is recommended to start coordination at the design development phase to catch all potential issues at the earliest time possible.

  1. Can shop drawing services reduce on-site installation issues?

Yes, professional shop drawing services significantly reduce installation issues by providing you with accurately coordinated and prefabrication ready drawings. Their early and in-depth clash detection workflow allows to solve the problems digitally rather than on-site .

  1. How long does a typical QA/QC review take?

It depends on project scope and complexity. Small packages might take 3 to 5 business days, while complex systems may take 1 to 3 weeks or even longer. It is crucial to plan milestones according to your fabrication lead times to avoid delays.