Fairfax County vs Loudoun County Building Permit Fees (2026)
Side-by-side comparison using official fee schedule data from both Virginia counties. For an identical $15,000 deck: Fairfax County totals $688.50 (verified). Loudoun County totals approximately $402.90 (estimated - see evidence quality notes below).
For a $15,000 deck addition (under 1,000 sq ft), Fairfax County charges $688.50 all-in (permit + plan review + state levy). Loudoun County charges approximately $402.90 all-in ($395 flat fee + USBC levy) - an estimated difference of roughly $285.60. The Loudoun total is an estimate because the fee schedule that could be located dates from July 2022, and the allocation of the 2% USBC levy across the bundled fee components has minor ambiguity.
- Loudoun County uses a bundled flat fee structure ($395 for small additions); Fairfax uses a percentage-of-cost formula (3% base).
- On low-to-mid-cost residential projects, Loudoun's flat fee tends to produce lower totals than Fairfax's percentage structure.
- For larger projects over $33,500 in construction value, Loudoun's 1% formula can approach or exceed Fairfax depending on plan review and zoning costs.
- The Fairfax total ($688.50) is verified against the current published fee schedule. The Loudoun total ($402.90) is estimated from a July 2022 schedule - verify current rates before budgeting.
- Both counties collect Virginia's mandatory 2% USBC state levy (Code of VA §36-139).
What Is Verified vs Estimated in This Comparison
This page does not present both totals as equally precise. Here is exactly what each figure is based on.
| Data Point | Fairfax County | Loudoun County |
|---|---|---|
| Fee schedule source |
Verified Official fee schedule, current |
Estimated Official HTML source, July 2022 - may be stale |
| Base permit fee method |
Verified 3% of construction value, $72 min |
Verified $395 flat (additions ≤1,000 sq ft) |
| Plan review fee |
Verified 50% of permit fee, published separately |
Verified (bundled) Included in $395 flat - not broken out |
| USBC state levy (2%) |
Verified Applied to permit + plan review subtotal |
Estimated Applied to full $395 - zoning component allocation unclear |
| Zoning permit |
N/A Not required in fee stack |
Bundled Included in $395 for small additions |
| $15,000 deck total | Verified: $688.50 | Estimated: ~$402.90 |
Fee Structure Comparison
Head-to-head comparison of the fee components each county applies to residential building permits.
| Fee Component | Fairfax County | Loudoun County |
|---|---|---|
| Fee calculation method | Percentage of construction value | Flat fee (small) or percentage (large) |
| Base permit fee - small project | 3% of cost · min $72 | $395 flat (≤1,000 sq ft additions) |
| Base permit fee - large project | 3% of cost (no upper cap published) | 1% of cost (>1,000 sq ft additions) |
| Plan review fee | 50% of permit fee (billed separately) | Bundled in $395 (small) · $335 flat (large) |
| USBC state levy | 2% of (permit + plan review) | 2% of bundled fee (levy base estimated) |
| Zoning permit | Not part of building permit stack | Bundled in $395 (small) · Separate, cost unlisted (large) |
| Minimum fee | $72 | $65 |
| Fee schedule source | Current official fee schedule | July 2022 official HTML schedule (verify for updates) |
| $15,000 deck - all-in total | $688.50 Verified | ~$402.90 Estimated |
| Estimated difference | ~$285.60 less in Loudoun Estimated difference | |
The estimated difference reflects the Loudoun July 2022 schedule. If Loudoun has updated fees since July 2022, the actual difference may vary. Verify with Loudoun County Building and Development at 703-777-0220 before using these numbers for project budgeting.
$15,000 Deck Addition: Line-by-Line Calculation
Same project, two counties, side-by-side arithmetic. Assumptions: deck is under 1,000 sq ft (qualifies for Loudoun flat fee) and $15,000 in declared construction value.
$15,000 × 3% =
$450.00
$450 × 50% =
$225.00
$450 + $225 =
$675.00
$675 × 2% =
$13.50
$675 + $13.50 =
$688.50
Building permit + plan review + zoning =
$395.00
$395 × 2% =
$7.90Note: levy applied to full $395 - levy on zoning component is not broken out separately in the fee schedule.
$395 + $7.90 =
~$402.90
This total is based on Loudoun's July 2022 fee schedule (the only published version located as of April 2026). Loudoun typically updates schedules July 1 annually. Current fees may differ. Verify before budgeting.
| Line Item | Fairfax County | Loudoun County |
|---|---|---|
| Base permit fee | $450.00 (3% of $15,000) | $395.00 flat (bundled) |
| Plan review fee | $225.00 (50% of permit) | Included in $395 |
| County zoning permit | N/A | Included in $395 |
| USBC state levy (2%) | $13.50 | ~$7.90 (est.) |
| All-in total | $688.50 Verified | ~$402.90 Estimated |
Why Fairfax and Loudoun Have Different Fee Structures
Both counties operate under Virginia's Uniform Statewide Building Code (USBC). The USBC mandates that all jurisdictions collect the 2% state levy (Code of VA §36-139), but it does not set the base permit fee rate. Each Virginia jurisdiction sets its own base fee method independently.
How Fairfax Sets Fees
Fairfax County uses a percentage-of-construction-value formula: 3% of declared construction cost, with a $72 minimum. Plan review is billed as a separate line item at 50% of the permit fee. This means the more a project costs, the higher the permit fee. A $15,000 project pays $450 in permit fees; a $100,000 project pays $3,000 - plus plan review and levy on top.
Fairfax publishes its fee structure through Land Development Services, and the formula has been in effect and verifiable from their current published fee schedule.
How Loudoun Sets Fees
Loudoun County takes a different approach for smaller residential projects: a single bundled flat fee covers the building permit, plan review, and county zoning permit together. For additions under 1,000 sq ft, the published rate is $395.00 - regardless of construction value within that size range. The 2% USBC levy is charged on top.
For larger additions (over 1,000 sq ft), Loudoun switches to a percentage formula: 1% of construction cost, plus a separate $335 plan review fee, plus a county zoning permit (cost listed as separate, not published in the fee schedule).
The bundled flat fee structure has a practical consequence: the exact USBC levy base is ambiguous because the fee schedule does not isolate the county zoning component within the $395. This is why the Loudoun total in this comparison is labeled "estimated."
Why the Difference Is Largest on Mid-Cost Projects
On a $15,000 deck, Loudoun's flat $395 is significantly below Fairfax's 3% formula ($450 base). But the gap narrows as project costs rise. At roughly $13,167 in construction value, Fairfax's 3% formula produces approximately $395 in base fees - similar to Loudoun's flat rate at that level. Below that threshold, Loudoun's flat fee is higher than Fairfax's percentage. Above it, Loudoun is lower until the project crosses 1,000 sq ft and Loudoun shifts to its 1% formula.
Frequently Asked Questions
Is Loudoun County always cheaper than Fairfax for building permits?
For typical residential additions under 1,000 sq ft (decks, room additions), Loudoun's $395 flat fee tends to produce a lower total than Fairfax's 3% formula - particularly for projects above roughly $13,200 in construction value. Below that threshold, Fairfax's percentage formula can be lower. For large projects over 1,000 sq ft, Loudoun's 1% formula applies and the comparison changes depending on zoning permit cost.
Is the $285.60 difference exact?
No. The $688.50 Fairfax total is verified from the current official fee schedule. The $402.90 Loudoun total is calculated from a July 2022 fee schedule, which is the only published version that could be located as of April 2026. The actual difference in 2026 depends on whether Loudoun has updated its schedule. Call Loudoun County Building and Development at 703-777-0220 to confirm current fees.
Does Loudoun charge a separate plan review fee?
For small additions (under 1,000 sq ft), no - plan review is bundled into the $395 flat fee. For larger additions, a separate $335 plan review fee applies. Fairfax always charges plan review separately (50% of permit fee).
Do both counties charge the Virginia USBC state levy?
Yes. Virginia's Uniform Statewide Building Code requires all jurisdictions to collect a 2% levy on building permits (Code of VA §36-139). Neither county can waive this. Fairfax collects it on the permit + plan review subtotal. Loudoun collects it on the bundled fee amount.
What if my project is over 1,000 sq ft?
For projects over 1,000 sq ft, Loudoun switches from its flat fee to a 1% of construction value formula, plus a $335 plan review fee, plus a separate county zoning permit (cost not published in the fee schedule). For a $100,000 addition, Loudoun's cost would be roughly $1,000 permit + $335 plan review + 2% levy = approximately $1,362.70 plus the unlisted zoning fee. Fairfax's formula produces $3,000 permit + $1,500 plan review + 2% levy = $4,590.00 for the same project - a much larger gap at the high end.
How do I get an official fee quote?
For Fairfax County: contact Land Development Services at 703-222-0801 or visit the PLUS online portal. For Loudoun County: call Building and Development at 703-777-0220 or use the LandMARC online portal. Only the building department can provide an official fee determination for your specific project.
Tools and Full Data Pages
Go deeper on either county or use the calculator for your project.
Official Sources
-
Fairfax County Land Development Services - Fee Schedule
fairfaxcounty.gov/landdevelopment/
Basis for Fairfax permit fee formula (3% of cost), plan review rate (50%), and minimum fee ($72). Current published schedule, verified March 2026. -
Loudoun County - Residential Additions and Alterations Fee Schedule
loudoun.gov/5387/Residential-Additions-and-Alterations
Basis for Loudoun $395 flat fee, 1% large-project formula, and $335 plan review. Effective date: July 1, 2022 (only published version located as of April 2026). Verify current schedule directly with Loudoun. -
Code of Virginia §36-139 - USBC State Levy (2%)
law.lis.virginia.gov/vacode/title36/chapter6/section36-139/
Statewide mandate for 2% USBC levy collected by all Virginia jurisdictions on building permits.