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SetbackIQ

Decks, porches and roof decks in 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.

A person last checked these rules on October 20, 2026. This is guidance only, so confirm with Fairfax County before you build.

The details

  • Attached to a house, open, 4 ft or lower: 6 ft into the front setback (not closer than 14 ft), 5 ft into a side setback, 20 ft into the rear setback (not closer than 5 ft).High confidence
  • Higher than 4 ft, or roofed: 12 ft into the rear setback, not closer than 5 ft. No side or front extension.High confidence
  • A deck or patio 8 in or less above grade may extend into any side or rear setback.High confidence
  • Railings up to 4 ft must be at least 50% open. Privacy screens and pergola features may rise 8.5 ft above the deck floor.High confidence

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Common questions

What are the rules for decks, porches and roof decks in Fairfax County?
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.

Sources

  1. Fairfax County Zoning Ordinance § 5100.2.D, setback regulations (corner lots, sight distance, permitted extensions). Checked 2026-10-21
    [Sight distance] Points must be 30 feet from the property lines extended... Sight distance must be maintained between two horizontal planes, one of which is three and one-half feet, and the other ten feet above the established grade... [Extensions] heating,…

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.