The Short Answer
A complete MEP set documents the mechanical (HVAC), electrical, and plumbing systems of a building through plan sheets, equipment schedules, single-line diagrams, riser diagrams, details, and written specifications. Each discipline shows equipment locations, sizing, routing, connections, and code-compliance information the contractor needs to install and the building department needs to permit. The set is stamped by licensed professional engineers who design and take responsibility for the systems.
Mechanical (HVAC) Sheets
Mechanical drawings show heating, ventilation, and air conditioning systems. These sheets include equipment locations (rooftop units, split systems, furnaces, exhaust fans), ductwork layouts with sizes and airflow quantities, diffuser and grille locations, and outside-air ventilation routing. Mechanical schedules list each piece of equipment with its capacity, electrical requirements, and performance data. Load calculations back up the equipment sizing and are typically provided with the set or on request.
Electrical Sheets
Electrical drawings document power distribution and lighting. Typical contents include a one-line (single-line) diagram of the service and distribution, panel schedules, power plans showing receptacles and equipment connections, lighting plans with fixture types and switching, and load calculations sizing the service to NEC requirements. Larger projects add low-voltage, fire alarm, and site-lighting sheets. Fixture schedules and legends define every symbol used on the plans.
Plumbing Sheets
Plumbing drawings cover domestic water, sanitary waste and vent, storm drainage, and often natural gas. These sheets include fixture locations, pipe routing and sizing, water heater and equipment details, and riser diagrams showing the vertical arrangement of waste, vent, and water piping. Fixture-unit calculations and fixture-count tables demonstrate that the system meets code for the occupancy served.
Schedules, Details, and Specifications
Beyond plans, an MEP set relies on supporting documentation. Schedules organize equipment data in tabular form so contractors can order and install the correct products. Details show typical connections, mounting, and installation methods. Specifications — either written notes on the drawings or a separate document — define materials, quality standards, and acceptable products. Together these ensure the installed systems match the engineer's design intent.
When Do You Need a Full MEP Set?
Most commercial permits require MEP drawings whenever mechanical, electrical, or plumbing systems are new or modified. Tenant improvements, ground-up construction, restaurant build-outs, medical and lab spaces, and change-of-occupancy projects almost always need coordinated MEP documents. Simple like-for-like equipment swaps sometimes need only limited sheets. When in doubt, the building department's submittal checklist is the definitive guide, and we can review your scope to confirm what's required.
Frequently Asked Questions
Do all three disciplines always appear in one set?
Not necessarily. A project may need only electrical, only plumbing, or a full three-discipline package. We scope the set to the actual work, so you only pay for the sheets your project requires.
Who stamps MEP drawings?
Licensed professional engineers in the relevant discipline design, review, and seal the drawings. The engineer accepts professional responsibility for the design — we do not stamp work we have not engineered or reviewed.
Are load calculations part of the drawings?
Calculations support the design and are provided with the set or upon request. Many jurisdictions require HVAC load calcs and electrical load calcs to be submitted alongside the plans.