Mechanical Section

The Section is responsible for mechanical review within DPIE’s Building Plan Review Division to ensure the public safety through the effective enforcement of International Mechanical Code, International Energy Conservation and Prince George’s County Codes. These include commercial and industrial plans. This is accomplished through mechanical engineering plan review and inspection related to the administration and enforcement of building mechanical and energy conservation codes and standards. The purpose of enforcing these codes is to provide safe and comfortable environments in which occupants may live, work, or perform recreational activities.
Mechanical Inspection
Mechanical reviewer studying plans
NOTICE:  Mechanical Trade Permit Applications Completed Online
The online application process has been instituted for HVACR/Mechanical Trade permits. Payment of permit fees are also processed online.

To be able to apply and have permits processed online, all HVACR Masters must first provide proof of a valid and current Maryland State issued license in DPIE’s Licensing Center, which will be verified by staff. Masters will then complete the Electronic Signature Acknowledgement Form. Upon completion of these two steps, Masters will be given permission to use the online system.

Please contact the Licensing Center at 301-883-3840 for additional information. 

Commercial Walk-through

Monday, Tuesday and Thursday, 8:00 a.m. to 3:00 p.m.
Wednesday, 9:00 a.m. to 3:00 p.m. 

Permit Application Type

  • CIW permit — (Commercial Interior/Remodel Walk-through) requires mechanical drawings for mechanical work to be performed. 
  • CEW permit — (Commercial Exterior/Parking Lot Lighting Walk-through) requires mechanical drawings for mechanical work to be performed. 
  • CUW permit — (Commercial Interior with Use and Occupancy Walk-through) requires existing mechanical drawings for a change in use type and/or occupancy load. Otherwise, provide drawings for mechanical work to be performed only
  • CGU permit — (New Construction/Major Renovation with Grading) requires complete sets of mechanical plans.

CIW - Commercial Interior Walk-through
CEW - Commercial Exterior Walk-through
CUW - Commercial Interior Walk-through with Use
CGU - Commercial Grading with Use

Mechanical Plan Review Requirement

  1. A scope of work is necessary for every project submitted for permit.
  2. Require original seal and signature by a Maryland Professional Engineer, including professional statement with expiration date of license.
  3. Ductwork layout, duct sizes, air devices and air flow (CFM) at each air device.
  4. Provide equipment schedule indicating total cooling/heating load, total supply air (CFM), outdoor air (CFM), entering/leaving dry bulb and wet bulb temperatures through coil, basis of design and equipment installation details.
  5. Equipment location(s) on the floor plan including labeling all equipment and identifying the space it serves.
  6. HVAC roof plan showing all roof-mounted equipment.
  7. HVAC piping floor plan (e.g., chilled water/heating, hot water/condenser water piping, refrigerant piping, condensate piping, steam piping, etc.)
  8. HVAC piping riser diagrams indicating pipe sizes and pipe fittings.
  9. Show combustion air provisions on the plans for the fuel-burning equipment. Size of openings and/or ducts and their points of termination should be indicated.
  10. Show commercial cooking hood, exhaust ducts, and exhaust fan(s) on the floor plans including all dimensions for each item.
  11. Show the make-up air unit and airflow rating on plans. Make-up air shall be approximately equal to the amount of the exhaust air.
  12. Provide mechanical energy calculation certification per International Energy Conservation Code (IECC); the software may be downloaded at
  13. Provide air balance diagram or table including the sequence of operation for all mechanical equipment.
  14. An outdoor air schedule or calculation in accordance with International Mechanical Code (IMC) 2018 table 403.3.1.1 must be included with any renovation, new construction or existing HVAC system.
  15. A manufacturer’s cut sheet must be provided for any domestic/commercial clothes dryer with an exhaust duct run greater than 35 feet.
  16. The drawings shall be sized to 24" x 36" (minimum) with a scale of 1/8" = 1' - 0" (minimum) and a text height of 1/8".
  17. Symbols and abbreviations list.