Skip to content
SetbackIQ

Floodplains, RPAs, wetlands and stormwater in Fairfax County, VA

Resource Protection Areas (the 100 ft buffers along streams), floodplains and grading are the big three. SetbackIQ checks the county's RPA map for your lot.

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

The details

  • RPA: any development or land disturbance generally needs county approval. Fences are allowed without an exception if they don't block drainage or remove trees. Sheds, garages, pools, gazebos and patios need an exception with a public hearing. Some decks qualify for an administrative waiver.High confidence
  • Floodplain: accessory uses like patios, decks and play areas are allowed without major fill. Pools, buildings and major fill need a special exception.High confidence
  • Stormwater and erosion control: more than 2,500 sq ft of disturbance needs a plan with silt controls.High confidence

Check a project at your address

SetbackIQ reads the zoning, flood zone, historic district, and environmental maps for your lot. Then it applies these rules.

What are you building?

Open the checker

Common questions

What if my lot is in a floodplain, Resource Protection Area or wetland in Fairfax County?
Resource Protection Areas (the 100 ft buffers along streams), floodplains and grading are the big three. SetbackIQ checks the county's RPA map for your lot.

Sources

  1. Fairfax County LDS, FAQs on Resource Protection Areas (Chesapeake Bay Preservation Ordinance, Chapter 118). Checked 2026-10-21
    Any development, land disturbing activity or other use within an RPA generally requires prior approval from the county... [Fences are allowed without an exception if they don't block surface flow or remove trees; sheds, detached garages, pools, gazebos and …
  2. Virginia Chesapeake Bay Preservation Area Designation and Management Regulations (9VAC25-830-80, -140). Checked 2026-10-21
    Land development may be allowed in the Resource Protection Area, subject to approval by the local government, only if it [is water dependent, is redevelopment, or fits the other listed cases]... The 100-foot wide buffer area shall be the landward component …
  3. Fairfax County Zoning Ordinance § 5104 (grading) and § 5105 (floodplain). Checked 2026-10-21
    Sod and soil may be removed from or added to any lot to a depth of not more 18 inches without approval of a grading plan if the total disturbed area is 2,500 square feet or less... [Floodplain] major fill includes any fill, regardless of amount, in an area …

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.