I know when it comes to many cities there are long permit processes and also there are specific air laws that go into each city.I would love to hear a story that goes over an experience pertaining to developing/rehabbing a property in the DC area. 

This is who will approve or deny your plans when you apply for a permit.

Quote from @Cheryl Abram: What legal filed docs are LPs entitled to see to help validate a deal's failure?

Permiting will be stricter I imagine. 

Short term rental permits are only granted to owners who will be renting their primary residence.

Does it require a highway occupancy permit if its on a state road, in my area it cost me around $1000 just to get the permitting and design for my driveway entrance.

For our ADU (garage conversion), I am handling the design/engineering and then selecting a final contractor once its permitted and ready to go. 

Similar areas that have legal under utilized permitted space convert to max studios that you can fit.  

Your main concern should be whether these bedrooms and bathrooms on the lower level are legal and have the proper egress require for fire code and livability.

Chris, you’re on the right track asking about permit timelines..