Decks, porches and roof decks across the DC area
What are the rules for decks, porches and roof decks? The rules differ at every jurisdiction line. Here is the short answer for each.
Disclaimer: This is general information, not legal or professional advice for any one property. Codes change. SetbackIQ is not a zoning determination, a permit, or a survey, and it does not replace an architect, engineer, or lawyer. Confirm with your building and zoning offices before you build, buy, or sign a contract.
| Where | Short answer |
|---|---|
| Washington, DC | Every deck and porch in DC needs a permit, including changes to existing ones. Low decks and the first 200 sq ft of a main-floor deck don't count toward lot occupancy. |
| Montgomery County, MD | Every deck needs a DPS permit, built to the county's deck guidelines. Unenclosed porches and decks may project into setbacks only as far as § 59-4.1.7 allows. |
| Prince George's County, MD | Decks need a building permit. DPIE offers homeowner walk-through review for simple decks. |
| Alexandria, VA | Every deck needs a building permit. Open decks up to 2 ft above grade may sit in any yard except the primary front yard, and a one-story front porch up to 10 ft deep may extend into the front yard if 10 ft of front yard remains. |
| Arlington County, VA | Every deck needs a building permit in Virginia. Decks and porches follow the yard encroachment rules in ACZO § 3.2.6. |
| Fairfax County, VA | Every deck needs a building permit in Virginia. A deck may extend into setbacks: an open deck 4 ft or lower, 20 ft into the rear setback and 5 ft into a side setback, never closer than 5 ft to the line. |
Towns and cities inside these counties (for example, Rockville, Gaithersburg, Bowie, Laurel, Herndon, Vienna, and Falls Church) have their own rules.