Washington, D.C.

The differences between Washington, D.C., and Maryland are essentially nonexistent in this situation. The building code considers vented crawl space the default, with non-vented crawl spaces only available in very specific situations. You can have a non-vented crawl space if you meet these guidelines:  

• Certain minimum coverage with a vapor barrier 
• A method of mechanical crawl space ventilation that allows for at least a certain rate of ventilation, with the type unspecified

Washington, D.C., also doesn’t require a termite gap. Any “under-floor spaces” need certain requirements for proper functioning:  

• Access openings that come through either the floor or wall 
• Flood resistance, but only in hazard areas

As you can see, these guidelines are essentially identical to those in Maryland. That’s because they’re adapted almost identically from the IRC. Your crawl space expert will be able to give you more insight into how they can make your crawl space work in a high-quality manner using these guidelines.