Welcome, you've gotten some great advice so far, and if I may, I'd like to take it a step further.
In case you haven't noticed, trafic in the DC area is undesireable on a good day. Street closings and traffic jams are just a way of life. While you'fe creating a house kit, you might start one for your vehicle too. If you happened to be over here in VA when the next attack occurs, you're not getting home because all the bridges will probably be closed at least temporarily. Doug has a good vehicle kit listed on this site that you can build and modify to fit your needs.

Just a thought,
Chris.