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Fairfax County Addition Permit Cost (2026)

Residential addition building permit fees in Fairfax County, Virginia, calculated under the Fairfax County Land Development Services Appendix Q FY2025 fee schedule. Fairfax County uses one stacked formula across all residential additions: 3% of declared construction value as the building permit fee, plus a 50% plan review fee on top of the building permit fee, plus the 2% Virginia state levy applied to the subtotal of building permit and plan review. The minimum permit fee floor is $110.16 (covers additions under ~$2,400 declared). A $50,000 addition pays $2,295.00 all-in.

Building Permit
3% of declared value
Plan Review
50% of building permit fee
Minimum Permit
$110.16 (under ~$2,400)
Virginia 2% State Levy
2% of (BP + plan review)
$50,000 Addition All-In
$2,295.00
Fee Status
Verified Appendix Q FY2025
What This Guide Covers - and What It Does Not

This guide covers: Fairfax County residential addition building permit fees as published in the Fairfax County Land Development Services Appendix Q FY2025 fee schedule. Coverage includes the 3% building permit formula, the 50% plan review fee, the 2% Virginia state levy on the subtotal, and the $72 minimum building permit fee floor. "Addition" in Appendix Q includes room additions, sunrooms, and enclosed porches added to an existing dwelling footprint.

This guide does NOT cover: Zoning approvals (setback verification, lot coverage, RPA or floodplain overlays, FAR/Floor Area Ratio review). Site plan or grading review for footprint expansion. HOA architectural approvals. Trade permits (electrical, plumbing, HVAC) - these are billed separately under Fairfax's trade fee schedules. Stormwater management or land disturbance permits if the addition triggers them. Demolition of existing structure if the addition replaces a tear-down.

When a Fairfax addition permit is required: Land Development Services requires a building permit for any addition that adds enclosed habitable space, conditioned space, or that modifies the structural shell of the existing dwelling. Sunrooms, enclosed porches, screened porches converted to four-season rooms, dormers that add habitable space, and second-story additions all qualify. Like-for-like deck-to-screened-porch conversions still require a permit because the structural envelope changes. Verify directly with Land Development Services at (703) 222-0801 before assuming exemption.

Declared value basis: Fairfax uses applicant-stated value or ICC Building Valuation Data (BVD), whichever is greater, as the declared value for the 3% formula. The ICC BVD is updated semi-annually and represents national average construction cost per square foot. For a 500 sq ft addition, the ICC BVD floor in 2025 is roughly $135-$165 per sq ft depending on construction type, producing a declared value floor of ~$67,500-$82,500 even if the contractor estimate is lower.

Key Takeaways
  • Fairfax County uses one stacked formula across all residential additions: 3% of declared construction value + 50% of that building permit fee as plan review + 2% Virginia state levy on the subtotal. The effective rate works out to ~4.59% of declared value above the $72 minimum floor. There is no fee cap, so high-value additions scale linearly without ceiling.
  • For a $50,000 addition: $1,500 building permit + $750 plan review + $45 state levy = $2,295.00. The arithmetic structure scales the same way at any declared value above the ~$2,400 minimum threshold. At $100,000 declared: $3,000 + $1,500 + $90 = $4,590.00. At $250,000 declared: $7,500 + $3,750 + $225 = $11,475.00. Plan review at 50% of the building permit fee is the second-largest component after the 3% rate.
  • Declared value in Fairfax is the higher of applicant-stated value or ICC Building Valuation Data per square foot. For a 500 sq ft addition, the ICC BVD floor in 2025 is roughly $135-$165 per sq ft depending on construction type, producing a declared value floor of ~$67,500-$82,500. Underdeclaring is not a strategy - Land Development Services adjusts upward at intake using BVD.
  • Trade permits (electrical, plumbing, HVAC) are NOT included in the addition permit. Most Fairfax additions trigger all three trade categories - electrical for new outlets/lighting/circuits, plumbing if the addition includes a bathroom or kitchen extension, HVAC for the duct extensions or new zone. Trade permits add roughly $200-$800 to the addition permit total depending on installer scope. They are quoted at intake under separate trade fee schedules.
  • The minimum permit fee floor is $110.16 ($72 building permit + $36 plan review + $2.16 levy). This applies to any addition with declared value below ~$2,400 - the threshold where 3% of value equals the $72 minimum. Almost no real-world addition falls below this floor; the minimum exists for very small enclosed-porch or dormer scope where the contractor cost is genuinely tiny.
  • Fairfax's 3% formula plus 50% plan review is the most expensive addition formula in the verified Virginia cluster. Loudoun County charges roughly 1% (July 2022 schedule) - about 1/3 of Fairfax. Chesterfield County uses a flat-tier structure that comes in well below Fairfax for $50k+ additions. Henrico County's value-based formula caps at $680. Richmond City's gentle $63 + $6.07/$1k formula is roughly 80% cheaper than Fairfax on a $50,000 addition. Virginia Beach's sq-ft formula is dramatically cheaper because it decouples the permit fee from declared value entirely.
  • Plan review at 50% of building permit is unusual - most jurisdictions either bundle plan review (Richmond, Henrico) or charge a flat plan review fee ($25-$100, like Virginia Beach or Chesterfield). Fairfax's 50% rate was set when the County's plan review process was deeper than industry standard; the rate has not been reduced even as digital intake reduced reviewer hours. The 50% surcharge is a structural reason Fairfax addition permits are expensive.
  • The Appendix Q FY2025 fee schedule was retrieved from fairfaxcounty.gov on April 16, 2026. The schedule is the current published rate sheet on the Land Development Services portal as of May 2026. Always confirm current rates with Land Development Services at (703) 222-0801 before filing.
Calculate Your Addition Permit All Fairfax Permit Fees

Fairfax Addition Permit Fee Components

Every Fairfax County residential addition permit is built from three components: the 3% building permit fee, the 50% plan review fee on top of the building permit fee, and the 2% Virginia state levy applied to the subtotal of building permit and plan review.

Component Amount ($50,000 example) How It Is Calculated
Building permit fee $1,500.00 3% of declared construction value. Minimum $72 floor for additions under ~$2,400.
Plan review fee $750.00 50% of the building permit fee. Always present, no waiver path for residential additions.
Subtotal $2,250.00 Building permit fee + plan review fee. State levy is applied to this subtotal, not just building permit.
2% Virginia state levy $45.00 2% of the $2,250 subtotal. Statutory under Code of Virginia §36-139 / USBC Section 107.2.
All-in $50,000 addition total $2,295.00 $1,500 + $750 + $45.00. Trade permits, zoning approvals, and contractor work are excluded.

Source: Fairfax County Land Development Services Appendix Q Fee Schedule, FY2025, retrieved from fairfaxcounty.gov on April 16, 2026. Verified by Munib Ur Rehman.

Worked Examples - Real Addition Projects in Fairfax County

Each example uses arithmetic from the Fairfax County Appendix Q fee schedule. The 3% + 50% plan review + 2% levy stack scales linearly with declared construction value. Plan review at 50% of building permit is the structural reason large additions get expensive fast.

Example 1: $25,000 small bump-out (kitchen extension, ~150 sq ft)

A homeowner builds a 150 sq ft kitchen bump-out on a single-family dwelling, declared construction value $25,000.

  • Building permit fee: 3% x $25,000 = $750.00
  • Plan review fee (50% of BP): $375.00
  • Subtotal: $1,125.00
  • 2% Virginia state levy on $1,125: $22.50
  • Total all-in addition building permit: $1,147.50

Trade permits (electrical for new outlets, plumbing if sink moves, HVAC for the duct extension) add roughly $200-$400 to this total at intake.

Example 2: $50,000 sunroom (300 sq ft enclosed three-season room)

A homeowner adds a 300 sq ft enclosed sunroom on the rear of an existing dwelling, declared construction value $50,000.

  • Building permit fee: 3% x $50,000 = $1,500.00
  • Plan review fee (50% of BP): $750.00
  • Subtotal: $2,250.00
  • 2% Virginia state levy on $2,250: $45.00
  • Total all-in addition building permit: $2,295.00
Example 3: $100,000 family-room addition (500 sq ft heated)

A homeowner builds a 500 sq ft heated family-room addition on the side of a single-family dwelling, declared construction value $100,000.

  • Building permit fee: 3% x $100,000 = $3,000.00
  • Plan review fee (50% of BP): $1,500.00
  • Subtotal: $4,500.00
  • 2% Virginia state levy on $4,500: $90.00
  • Total all-in addition building permit: $4,590.00
Example 4: $250,000 second-story addition (1,000 sq ft over existing garage and family room)

A homeowner adds a 1,000 sq ft second-story addition over an existing garage and family room, declared construction value $250,000.

  • Building permit fee: 3% x $250,000 = $7,500.00
  • Plan review fee (50% of BP): $3,750.00
  • Subtotal: $11,250.00
  • 2% Virginia state levy on $11,250: $225.00
  • Total all-in addition building permit: $11,475.00

Note: a $250,000 second-story addition triggers structural review of the existing first-floor framing and footings. The 50% plan review fee covers the deeper structural review without an additional surcharge. Trade permits add another $400-$1,200 depending on bath/HVAC scope.

Calculate Your Fairfax Addition Permit

The PermitPrice fee calculator supports Fairfax's 3% + 50% plan review + 2% levy stack directly. Enter your declared construction cost and the calculator returns the all-in addition permit cost broken down by component.

Calculator coverage for Fairfax additions: the 3% formula + 50% plan review + 2% Virginia state levy. The minimum permit fee floor of $110.16 is enforced for declared values under ~$2,400. Trade permits are not modeled in the calculator.

Open the Permit Fee Calculator

Fairfax Addition Permit Cost vs Other Verified Virginia Jurisdictions

Fairfax's 3% + 50% plan review formula is the most expensive addition permit structure in the verified Virginia cluster. The $50,000 declared addition produces $2,295.00 in Fairfax versus $500-$700 in most peer jurisdictions. The savings outside Fairfax compound at higher declared values.

Jurisdiction Addition Formula $50,000 Addition All-In
Fairfax County 3% of value + 50% plan review + 2% levy $2,295.00
Loudoun County ~1% of value (July 2022 schedule) ~$500 (estimated)
Henrico County $100 + $6/$1k over $5k (capped $680) $370.60 (capped path)
Richmond City $63 + $6.07/$1k over $2k + 2% levy $361.45
Chesterfield County Flat tier $399 + $50 site + 2% levy $457.98 (flat-tiered)
Virginia Beach City $50 + $7/100 sq ft heated + $100 PR + 2% levy $196.70 (500 sq ft heated)

Comparison units differ: Fairfax/Loudoun/Richmond/Henrico use declared construction value; Chesterfield uses a flat-tier scheme; Virginia Beach uses sq ft. Trade permits are excluded from every row. The 500 sq ft heated addition assumed in the Virginia Beach row is the closest like-for-like proxy at the $50,000 declared value level.

Side-by-Side Math

For full breakdowns of how Fairfax compares against neighboring jurisdictions on additions, decks, and pools, see the dedicated comparison pages.

Frequently Asked Questions

A Fairfax County residential addition building permit costs 3% of declared construction value as the building permit fee, plus 50% of that as plan review, plus 2% Virginia state levy on the subtotal. A $25,000 addition pays $1,147.50. A $50,000 addition pays $2,295.00. A $100,000 addition pays $4,590.00. A $250,000 addition pays $11,475.00. The minimum permit fee floor is $110.16. Trade permits (electrical, plumbing, HVAC) are billed separately and add roughly $200-$1,200 depending on installer scope.
Per Fairfax County Appendix Q, "addition" includes room additions, sunrooms, enclosed porches added to existing footprint, second-story additions, dormers that add habitable space, and bump-outs. The defining test is whether the project adds enclosed habitable or conditioned space, or modifies the structural shell of the existing dwelling. Decks, fences, sheds, and accessory structures are billed under their own Appendix Q line items, not the addition formula. Screened porches (open to outdoor air on three sides) are typically billed as an addition because the structural envelope still gets reviewed.
Fairfax stacks three full-strength components: a 3% rate on declared value, a 50% plan review markup on top of that, and the 2% Virginia levy on the combined subtotal. Effective rate ~4.59% of declared value. Richmond uses one gentle bundled formula at $63 + $6.07/$1,000 (effective ~0.7%). Henrico caps at $680 + 2% levy = $693.60. The differences come from each schedule's structure, not from inspection quality. Fairfax's 50% plan review surcharge in particular is the structural reason large additions get expensive fast - it is unusual nationally and far above Virginia peer norms.
No. Fairfax declared value is the higher of applicant-stated value or ICC Building Valuation Data per square foot. For a 500 sq ft addition in 2025, the ICC BVD floor is roughly $135-$165 per sq ft depending on construction type, producing a declared value floor of ~$67,500-$82,500 even if the contractor estimate is lower. Land Development Services adjusts upward at intake using BVD. Underdeclaring is not a strategy - it triggers a desk review, delays the permit, and may trigger an audit of related contractor invoices.
No. Trade permits are filed separately under Fairfax's trade fee schedules and are not included in any number on this page. Most additions trigger all three trade categories: electrical for new outlets/lighting/circuits, plumbing if the addition includes a bathroom or kitchen extension or relocation, HVAC for the duct extensions or new zone equipment. Trade permits add roughly $200-$1,200 to the addition permit total depending on installer scope, fixture count, and equipment count. The licensed trade contractors pull these permits separately at intake.
Yes. Fairfax County Land Development Services routes addition applications through Zoning Administration before building plan review can issue. Setback verification, lot coverage, FAR (Floor Area Ratio), Resource Protection Area (RPA), and floodplain overlays are all checked at zoning. Zoning approval can take 2-4 weeks for straightforward setback questions and longer for RPA, FAR, or special-exception cases. The Appendix Q building permit fees on this page do not include any zoning fees - those are separate and quoted at zoning intake.
Per Fairfax County refund policy, the plan review fee is consumed when plan review begins and is not refundable after that point. The building permit fee is refundable in part if the permit was issued but no inspections were performed - typically 50% refund. The 2% Virginia state levy is not refundable. The exact refund schedule depends on which milestones the application reached. Confirm directly with Land Development Services before cancelling and ask for a written refund quote.
No. The $2,295.00 Fairfax addition permit fee (at $50,000 declared) is the County building permit cost only - the cost to apply, get plan review, and have inspections performed. It does not include any contractor work. A 300 sq ft sunroom installed in the Fairfax market typically runs $40,000-$80,000 for the contractor scope (foundation, framing, windows, roofing, finishes, labor). A 500 sq ft heated family-room addition runs $80,000-$150,000+. The permit fee is a meaningful but small line item in your overall addition project budget; the bulk is contractor scope. PermitPrice tracks only the County permit fee component.

Sources

Official .gov Sources - Verified May 2026
  • Fairfax County Land Development Services Appendix Q Fee Schedule (FY2025) FY2025 - Fairfax County Land Development Services - Primary source for the residential addition formula (3% of declared construction value + 50% plan review fee), the $72 minimum building permit fee floor, and the residential addition scope definition (room additions, sunrooms, enclosed porches). Retrieved on April 16, 2026 Verified FY2025
  • Fairfax County Land Development Services Accessed May 9, 2026 - Land Development Services Department - Index page linking the published fee schedule, application forms, online portal (PLUS), and inspection scheduling. Phone (703) 222-0801
  • Code of Virginia Section 36-139 - USBC State Levy Authority Current - Virginia General Assembly - Authorizing statute for the statewide 2% building permit surcharge applied across all Virginia jurisdictions, including Fairfax County addition permits
Next Step

Calculate your specific Fairfax addition permit cost, see all Fairfax fee categories, or compare against neighboring jurisdictions.

Fairfax Deck Permit Guide → Fairfax Pool Permit Guide → Virginia Addition Permit Guide → All Guides →
Always verify current addition permit fees directly with Fairfax County Land Development Services before budgeting or filing. The Appendix Q FY2025 fee schedule on fairfaxcounty.gov is the most recent posted as of May 9, 2026. Call (703) 222-0801 or visit the Land Development Services portal to confirm addition permit rates, ICC BVD declared-value floors, plan review requirements, and zoning approval status before submitting an application.
Disclaimer: All fee information on PermitPrice is for informational purposes only and is not an official permit quotation. Actual permit fees are determined by Fairfax County Land Development Services at the time of application. Declared construction value is the higher of applicant-stated value or ICC Building Valuation Data per square foot; LDS adjusts upward at intake using BVD. Trade permit costs (electrical, plumbing, HVAC) are not modeled in this guide and depend on installer scope. Zoning fees, site plan review fees, and stormwater permits are separate from Appendix Q building permit fees. Verify directly with Land Development Services before filing.

Written by: Munib Ur Rehman

Data verified against official fee schedule documents.