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Department of Buildings

In observance of the Emancipation Day holiday, DOB will be closed on Tuesday, April 16, 2024; no construction will be allowed on this day without an after-hours permit. You may report illegal construction by submitting an Illegal Construction Inspection Request Form during normal business hours or by calling 311.

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Get a Supplemental Permit

DOB now lets you apply, pay for, and get your supplemental building permits online.  These permits are required to install supplemental systems in buildings, per § 105.1.13 of the DC Municipal Regulations (DCMR). Only licensed DC contractors for each specific trade may apply for these permits. You may be required to complete a building permit for the supplemental permit.

Important Details

  • You cannot save a partly-completed application. 
  • You must complete each box marked with an asterisk (*) before you can pay for and receive your permit.
  • You may pay with Visa, MasterCard, or Discover.
  • If the fee for your supplemental permit is more than your available credit, you cannot get the permit online. 
  • You will get a supplemental permit application that you can print and bring in with payment. 
  • Supplemental permits cannot be issued online if the work address is in a historic or fine arts district. The supplemental permit is issued as an Adobe PDF file. You can save it on your computer and print it.

OSPI Permit Types

  • Electrical Supplemental Permit (includes Fire Alarm)
  • Plumbing Supplemental Permit
  • Gas Supplemental Permit
  • Air Conditioning or Refrigeration Supplemental Permit
  • Fuel Burning Equipment Supplemental Permit
  • Miniature Boiler Supplemental Permit
  • Unfired Pressure Vessel Supplemental Permit

Apply for a Permit



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