Quick-Service Restaurant (QSR) projects are booming across the U.S., with strong market expansion and continued investment in restaurant construction — the industry reached an estimated $9.1 billion in 2025.
Yet even as demand grows, many QSR projects face permit drawings — especially MEP (Mechanical, Electrical & Plumbing) sets — getting rejected during plan review, leading to costly permit delays, redesigns, and stalled openings for architects and developers.
Below, we break down the real reasons Illinois authorities reject QSR MEP plans, answer architect-driven questions, and explain how to avoid these delays.
Common Reasons QSR MEP Drawings Are Rejected in Illinois
Key Issues That Lead to Rejection
Many architects ask: Why do QSR MEP drawings get rejected in Illinois?
The answer starts with code compliance, incomplete details, and coordination gaps.
Primary reasons include:
- Missing compliance documentation for HVAC, electrical, or fire systems
- Insufficient coordination between architectural and MEP systems
- Improper electrical load calculations that don’t reflect kitchen demands
- Incomplete plumbing and drainage plans
- Fire protection mismatches with hood ventilation systems
These can lead to multiple corrective submissions, which expand approval timelines and increase costs.
This isn’t unique to restaurants — nearly 98 % of U.S. construction projects face delays, often extending 37 % longer than expected due to workflow and review challenges.
Avoid Illinois Permit Rejections Before Submission
Illinois-Specific Code Issues Architects Miss
What Reviewers Look For in Illinois?
Architects sometimes wonder: What Illinois building codes apply to QSR MEP plans?
In Illinois (including Chicago and Cook County), plan reviewers expect:
- Detailed HVAC load calculations matching ASHRAE / IECC requirements
- Gas piping and interlock documentation for kitchen equipment
- Grease interceptor plans that reflect sewer authority expectations
- Clear plumbing layout and trap sizing
- Fire protection system design compliant with NFPA standards
Errors here can trigger rejections because reviewers interpret codes strictly at the permit stage — especially around kitchen exhaust, makeup air, and grease control.
Learn more about grease trap sizing and installation requirements from industry guidance that details minimum retention and interceptor volumes for commercial kitchens.
HVAC & Hood System Errors That Trigger Rejection
Typical HVAC Failures in QSR Submissions
Architects often ask: Why do hood and HVAC plans fail review?
Common issues include:
- Undersized hood exhaust systems relative to cooking equipment
- Missing or incorrect make-up air calculations
- Inaccurate zone control strategies for dining vs. kitchen spaces
- Lack of compliance with local energy codes
Misalignment between HVAC layouts and architectural plans is one of the most frequent causes of plan comments, because it affects indoor air quality, comfort, and code compliance for commercial kitchens.
Plumbing & Grease Interceptor Mistakes
Plumbing Failures That Cause Rejections
In restaurant environments, plumbing systems are under extra scrutiny because of grease, water waste, and sanitation.
Architects frequently face questions like:
- Is a grease interceptor required, and how is it sized?
- Are floor drains located and sloped correctly?
Issues that trigger comments or rejection include:
- Incorrect interceptor sizing
- Improper waste line slopes
- Missing clean-outs or traps
- Lack of documentation for health department review
Proper integration of plumbing with kitchen layouts is essential to avoid resubmissions.
Get Permit-Ready QSR MEP Drawings in Illinois
Electrical Coordination Issues Reviewers Flag
What Causes Electrical Plan Comments
A common architect concern is: Do electrical load calculations impact permit approval?
Yes — and they’re often scrutinized.
Key problems include:
- Incomplete electrical load calculations
- Missing or unclear single-line diagrams
- Misplaced emergency shutoff requirements
- Lack of clarity on panel schedules
These issues force reviewers to request revisions, slowing down approvals.
How Architects Can Avoid Costly Revisions
Best Practices for Permit-Ready Submissions
Architects repeatedly ask: How can we reduce mep permit delays?
Here are proven strategies:
- Integrate MEP engineers early in the design process
- Include all compliance calculations and documentation
- Drive MEP coordination before finalizing architectural layouts
- Conduct internal QA/QC reviews before submission
- Use Clash detection tools (e.g., BIM) during design
- Provide clear annotated plans and schedules
Bundling accurate details helps reviewers approve plans quickly, reducing repeated comments.
Successful QSR projects start with early coordination between architects and engineers specializing in restaurant MEP design, ensuring permit-ready submissions.
Need help with integration? Check out our related blog Three Problems You Can Avoid by Working with Qualified MEP Designers that covers how early engineering involvement speeds approvals.
When to Involve an Illinois-Based MEP Engineer
Why Local Expertise Matters
Many architects wonder: When should we bring in a local MEP engineer for QSR projects?
Best time:
During schematic or early design development.
Bringing in specialists early prevents:
- Misalignment of building systems
- Missed code requirements
- Permit delays and extra cost
Local MEP engineers experienced with Illinois codes speed approvals and ensure your project avoids unnecessary resubmissions.
For project consultation, see our comprehensive services at QSR MEP Design Services in Illinois
Get Permit-Ready QSR MEP Design
Don’t let permit comments delay your QSR project. Our Illinois-based MEP engineers specialize in:
- Permit-ready MEP drawings
- Code-compliant HVAC, electrical, and plumbing systems
- Fire protection coordination
- AHJ review support
Request a QSR MEP Design Proposal Today
Final Thoughts
MEP plan rejection is common, but avoidance is predictable. By understanding what reviewers expect — from HVAC load calculations to electrical coordination and grease interceptor sizing — you can significantly reduce permit delays in Illinois.
The restaurant construction market continues to evolve, and with restaurant construction projected at billions in 2025, efficient design and compliance will be key to staying ahead of competitors.
If you’re planning a QSR or fast-food restaurant project in Illinois, Nearby engineers can help you move faster with code-compliant, coordinated MEP design.
