The rules are from the County's LDA / Stormwater Permit Overview and its FAQ, read 23 October 2026.
The thresholds
| Total disturbed area | What Arlington requires |
|---|---|
| Under 2,000 sq ft | No LDA/SWM permit |
| 2,000 to 2,499 sq ft | A survey of the disturbed area with on-site markings, and County-approved silt fence or other perimeter control installed before the permit is issued |
| 2,500 sq ft or more | LDA/SWM permit |
| Separate projects within two years | Added together toward the threshold |
| 1 acre or more | Also the state General VPDES permit for construction discharges |
The FAQ lists what counts: new houses, buildings, additions, expansions, garages, demolition of existing structures, driveways, sidewalks, landscaping and utility trenching.
How the County measures it
The disturbed area is bigger than the footprint. The FAQ adds:
| Element | Work zone counted |
|---|---|
| New structure | 10 ft around it (or to the property line if closer) |
| Demolished portion, or a story being added | 10 ft around it |
| Driveways, sidewalks, ground-level decks | 5 ft |
| Utility lines | 5 ft, centered on the line |
| Access | A path at least 10 ft wide from the street or driveway to the work |
A 20-by-25-foot rear addition (500 sq ft) with the 10-foot zone becomes a 40-by-45-foot area, 1,800 sq ft, before the access path and any new utility trench. That is why the County's rule of thumb puts a 1,000 sq ft footprint over the line, and why a second-story addition counts too: the 10-foot zone applies around "any story being added".
What the permit asks for
Since 2021, single-family projects must "meet state stormwater quantity standards in addition to the stormwater quality previously required". The overview also lists soil de-compaction and amendment, not concentrating runoff toward downhill neighbors, accounting for existing forest, retaining walls and fill, as-built documentation for grading and trees, and conditions on adding impervious surface after completion. There are three routes: the standard LDA 2.0 permit, an Alternative Compliance Option, and a Streamlined LDA/SWM 2.0 permit for moderate-scale single-family projects (effective 13 September 2021), detailed in Section 2.9 of the County's Stormwater Manual. A lot with a Resource Protection Area (RPA) follows Section 4.
What it means for hiring
Ask any builder or designer, before you sign:
- What is the disturbed area on the plan, by the County's work-zone method? An addition designed to stay under 2,000 or 2,500 sq ft avoids the survey, the silt fence or the full LDA permit.
- Who prepares the stormwater plan and pays for it? It is a separate document from the architectural drawings.
- Is the schedule built around LDA review? The County pages give no review time, so ask the builder what their last Arlington LDA took.
| Arlington, October 2023 to September 2026 | Additions | New homes |
|---|---|---|
| Permits | 750 | 512 |
| Firms | 348 | 119 |
| Usual filed value | $80,000 | $500,000 |
| Middle half of firms' usual job | $48,000 to $232,500 | $400,000 to $800,000 |
| Finished (permits a year or more old) | 88.5% | 94.4% |
| Usual days from issue to final | 235 | 291 |
| Firms with one permit | 65.2% | 49.6% |
| Firms matched to an active Virginia license | 96.0% | 96.6% |
65.2% of addition firms filed a single Arlington permit in three years. For a project near the 2,500 sq ft line, a builder who has done several Arlington additions is more likely to have been through LDA review; new-home builders, who almost always cross the threshold, are a more concentrated group, with 32.4% of permits held by the five busiest.
Compare Arlington addition builders →
Prices by firm: Arlington addition cost and new home cost. New-home builders: Arlington new home list. Past permits: Arlington building permit search. Counts by year: Arlington permit statistics.
What this does not tell you
Our file counts building permits; it does not show which ones also needed an LDA permit, or how long LDA review took. The County pages read for this article list no fee amounts, review times or bond requirements, so those come from the fee schedules or the stormwater team (stormwatermanagement@arlingtonva.us). The addition example is arithmetic on the FAQ's work zones, not a County calculation.
How we know this
Thresholds, work zones, covered activities, the 2021 requirements and permit routes are quoted from Arlington County's LDA / Stormwater Permit Overview and FAQ pages, read 23 October 2026; the 500 sq ft addition example applies the FAQ's 10-foot work zone. Our figures are Arlington County residential building permits classified as additions and new homes, October 2023 to September 2026; finished share uses permits a year or more old, and license status is matched to Virginia DPOR records by name.
Numbers come from Arlington County, VA building and trade permits, data through October 14, 2026. Nobody paid to be on this page and nobody can.
Questions
- When do I need an LDA permit in Arlington County?
When the project disturbs 2,500 square feet of land or more, counting separate projects within two years together. Under 2,000 square feet no LDA/stormwater permit is needed; from 2,000 to 2,499 you need a survey of the disturbed area with site markings and County-approved silt fence or other perimeter control before the building permit is issued.
- Does a home addition in Arlington need a stormwater permit?
If it pushes disturbance to 2,500 square feet or more, yes. The County's rule of thumb is that a new building footprint of 1,000 square feet or more usually means disturbance over 2,500, because the County adds a 10-foot work zone around the structure, 5 feet around driveways, sidewalks and ground-level decks, 5 feet centered on utility lines, and a 10-foot access path.
- How is disturbed area calculated in Arlington?
The footprint plus work zones: 10 feet around a new structure (or to the property line if closer), 10 feet around any demolished portion or added story, 5 feet around driveways, sidewalks and ground-level decks, 5 feet centered on utility trenches, and a minimum 10-foot-wide access path from the street or driveway.
- How much does an LDA permit cost in Arlington?
The County's LDA pages do not list a dollar amount; fees are set in the separate Inspection Services, Zoning and Department of Environmental Services fee schedules. For scale, the usual Arlington addition permit in our file was filed at $80,000 and the usual new home at $500,000.
- What changed in Arlington's stormwater rules in 2021?
Since 2021, single-family projects that need an LDA permit must meet state stormwater quantity standards as well as the quality standards required before. A Streamlined LDA/SWM 2.0 permit for moderate-scale single-family projects took effect on 13 September 2021.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
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For one city
- Land Disturbing Activity / Stormwater Permit Overview — Arlington County (accessed 2026-10-23)
- Land Disturbing Activity/Stormwater Permit: Frequently Asked Questions — Arlington County (accessed 2026-10-23)