The Short Answer: Most Commercial Projects
Any project that modifies or installs mechanical, electrical, or plumbing systems in a commercial building requires MEP engineering documents for the building permit. These documents — signed and sealed by licensed professional engineers — tell the plan reviewer and building inspector exactly what systems are being installed and how they comply with the applicable codes.
What Triggers MEP Plan Requirements
Mechanical (M Permit)
- HVAC system installation or replacement
- Ductwork modifications or new duct systems
- Commercial kitchen exhaust and make-up air
- Ventilation systems
- Rooftop equipment installation
Electrical (E Permit)
- New or expanded electrical service
- Panel additions or replacements
- Lighting systems
- EV charging infrastructure
- Generator and emergency power systems
- Solar PV systems
Plumbing (P Permit)
- New or modified water service
- Plumbing fixture additions or relocations
- Gas piping modifications
- Grease interceptors
- Sewer line work
What's in a Permit-Ready MEP Set
A complete MEP permit package includes: plans showing equipment locations, duct and pipe routing, and fixture layouts; schedules listing equipment sizes and specifications; one-line diagrams for electrical; calculations demonstrating code compliance (load calculations, ventilation calculations, energy compliance); and PE stamps from the engineer of record for each discipline. Some jurisdictions also require a separate energy compliance package (Title 24, IECC compliance forms).
Tenant Improvements Are the Most Common Trigger
Commercial tenant improvement projects are the most frequent driver of MEP permits. Even "simple" TIs — a new coffee shop, a medical suite, an office renovation — typically touch all three MEP disciplines and require a full engineering package. Starting the engineering process as soon as the architectural design is underway keeps permitting on schedule.