Land Development Services

Fairfax County, Virginia

CONTACT INFORMATION: Our offices are open to the public by appointment only from 9 a.m. - noon. Regular hours for calls and emails are 8 a.m. – 4 p.m., Monday through Thursday, and 9:15 a.m. - 4 p.m. on Friday.

TTY 711

12055 Government Center Pkwy
Fairfax, VA 22035

Bill Hicks,

Additions, Garages and Sunrooms


This information is the most common for how to obtain the necessary permits for your project and is not representative of all the conditions you may encounter.

Permits and Fees

You will be required to obtain a residential addition building permit, mechanical permit (for new heating and air conditioning system), electrical permit and plumbing permit (if new plumbing fixtures are installed).

Fees vary depending on the scope of your project; use the online fee estimator to help determine your costs.

Documents Required

When applying for a permit online, you must upload building plans, site-related plan, Property Ownership Form (when property ownership must be verified), and Permit Authorization Form (when the applicant is neither the owner nor a contractor).

Permit Process

Follow the steps below to obtain the necessary approvals and permits for your project. Vienna and Clifton residents require additional approval from their respective towns. You may obtain the status of your permit application at any time online.

  • Step 1) Permit Application

    Permit Application

    Begin your permit application process online using FIDO. Follow the prompts to create your FIDO account and apply for your residential addition building permit and pay the appropriate fees. Additional steps are required for your eplan upload process; learn more. Once complete, you will be invited by email to upload your required documents to ProjectDox for submission to the county.

  • Step 2) County Review

    County Review

    County staff from the Permit Application Center, Health Department (if on well or septic), Building Plan Review and Zoning will review your package for completeness and compliance with the building code and county ordinances. You will be notified of any deficiencies. Plan corrections, resubmission fees and additional supporting documents may be required.

    Residential Walk-thru

    Residential Walk-Thru allows customers with one-story structures less than 500 square feet to apply for a permit and obtain a review from county staff within 24 hours of plan acceptance.

  • Step 3) Permit Issuance

    Permit Issuance

    Once all county reviews are approved and outstanding fees have been paid, you can access your approved plans in ProjectDox and permit in FIDO. The permit must be printed and posted at the job site, and the approved plans must be also printed in full-size and available to the inspector.

  • Step 4) Trade Permits

    Trade Permits

    Electrical and plumbing permits can be obtained online after the building permit has been issued. Plans are not required. Input the building permit number issued in Step 3) when prompted for the “associated building permit number” in FIDO. If you are installing a new HVAC system, you must upload a Residential HVAC Certification for review prior to issuance of the mechanical permit.



You are required to obtain inspections from the county for your project. The county must be notified when the stages of construction are reached that require an inspection; see the table below. Ladders, scaffolds and other equipment necessary to access construction must be provided to the inspector. Schedule, cancel or modify an inspection online or with the Fairfax County smartphone app.







  • Footing trench/formwork ready for concrete; bottom of trench on solid soil.

Residential wall (masonry or concrete foundation wall)


  • Forms ready for concrete with reinforcing steel in place.
  • Masonry ready for grout with reinforcing steel in place.

Plumbing groundwork


  • Under-slab sewer and water pipe in place.



  • Parging and waterproofing installed.



  • Area prepared with gravel, vapor barrier and reinforcing steel in place.
  • Drain tile in place, properly sloped and tied to proper outfall.

Combined inspection:

  • Building framing
  • Mechanical concealment
  • Plumbing concealment
  • Electrical concealment


  • Vents and gas, sewer or water pipe installed and pressure tested.
  • Electrical wiring and boxes installed.
  • Ductwork installed.
  • Platform for HVAC equipment installed.
  • Sill plates secured to the foundation.
  • Stairways in place and secured.
  • Sub-flooring installed.
  • Structure weather tight.
  • Wall and roof sheathing installed.
  • Windows and doors installed.



  • Wall, ceiling and crawl space insulation in place.

Combined inspection:

  • Building final
  • Mechanical final
  • Plumbing final
  • Electrical final


  • Plumbing fixtures and piping installed.
  • Roughed-in plumbing fixtures permanently capped.
  • Appliances, fixtures, outlets, panels, switches, etc. installed.
  • Panel box index completed.
  • HVAC equipment operating properly.

Building Plans

When applying for a permit, the plans must meet or show the following, if applicable:

  • Minimum scale of ¼ inch = 1 foot; fully dimensioned.
  • Minimum sheet size: 11 x 17 inches.
  • Code year and local design criteria used for the design.
  • Name, address and occupation of the designer.
  • If prepared by a Virginia registered design professional, show the electronic signature, seal and date.
  • List of materials used, including strength, wood species, grade.
  • Live load and dead load.
  • Foundation plan, footing details and basement wall design.
  • Thickness of slab-on-grade, gravel base and vapor barrier.
  • Garage slab slope toward garage door.
  • Crawl space vent and access locations.
  • Floor plans of all levels with each room function labeled.
  • Location of smoke and carbon monoxide alarms.
  • For garages, ½-inch drywall applied to the walls and 5/8-inch, Type-X applied to ceilings.
  • 20-minute fire-rated door between an attached garage and house.
  • If detached garages are within 3 feet of the existing house, show drywall and fire-rated door equivalent to attached garages.
  • Outlets in garages must be GFCI. Garages shall include at least one outlet and one ceiling mounted light with a wall switch.
  • Structural framing plans for floors and roof identifying all members’ sizes, span lengths and spacing.
  • For sunrooms on an existing deck, provide details on the deck attachment to house and the deck’s lateral load resistance at the posts.
  • Manufacturer’s design specifications of pre-fabricated fireplaces.
  • Manufacturer’s name, series number and depth of all manufactured wood products.

Truss Shop Drawings

Roof or floor truss shop drawings are required to be reviewed by the county and can be submitted after the permit has been issued but before erection. Submit online.



  • Typical wall section with sheathing thickness and type.
  • Wall bracing. For more information, see our wall bracing publications.
  • For additions and sunrooms, insulation R-values and fenestration U-factors. See our Energy Conservation website.
  • Exterior elevations noting dimensions and locations of windows and doors.
  • Building height; maximum height is 35 feet measured from grade to roof midpoint.
  • Jacuzzi/whirlpool tub manufacturer’s information.
  • Location of safety glazing.
  • Structural calculations for main wind reinforcing system and components and cladding may be required for pre-made sunrooms. Calculations must include:
    • Wind pressure per ASCE 7.
    • Shearwall and diaphragm design per SDPWS.
    • Electronic signature and seal of the registered design professional responsible for the design.

Site-Related Plans

To determine your project’s impact on your property, one of the site-related plan types listed below must be submitted. To learn more, see our Site-Related Plans publication or contact the Permit Application Center.


House location surveys, or plats, are required for the construction of additions and accessory structures. The proposed construction must be drawn on a plat to-scale with the dimension from the lot lines to ensure compliance with minimum yard requirements (setbacks). To learn more, see our Site-Related Plans publication.

Why do plats have to be “to-scale”? What exactly does that mean?
A “to-scale” plat is an exact copy of the original plat, with all lines being identical to that of the original. Lines on the original plat are to-scale to reflect, for example, that one-inch on the plat equals 30 feet, rather than one-inch on the plat equaling three feet when it is taken out of scale. A to-scale copy must be on the same sheet size as the original (for instance, if an original plat is printed on an 11” x 17” sheet, then only a copy on that same sheet size is acceptable). Plats that have been photographed, scanned on a phone app, faxed, reduced, enlarged or otherwise altered are not to-scale and cannot be accepted due to poor resolution and lack of detail (loss of accurate measurement).

Where’s my plat?
Search your residential loan closing documents or contact the lending institution from which your mortgage was obtained. If you do not have a copy, submit a request to determine if your plat is located in existing county files. If all these efforts have been exhausted, you will have to hire a private land surveyor to have a new plat prepared.


A conservation plan is much like a house location plat, but also shows erosion and sediment control measures. You can use one when your project disturbs 5,000 square feet or less and drainage improvements and water quality controls are not required. If you do not meet these conditions, you must submit a grading plan.


A grading plan is a drawing of your site which shows topography, new construction and improvements and is required when your project disturbs more than 2,500 square feet, blocks existing drainage patterns or soil is to be cut or filled more than 18 inches.

Fairfax Virtual Assistant