Any construction done without required building permits is illegal construction. Illegal construction is a public danger: it can hurt people and property.
To report illegal construction, call DCRA’s Illegal Construction Unit, at (202) 442-STOP (7867) or call 311 during non-business hours and you will be routed to an on-duty inspector.
Please give the address and describe the illegal construction. DCRA will schedule an inspection to investigate.