Data through September 2026 · updated 19 Oct 2026
229 ADU and casita permits were issued in Montgomery County, October 2024 through September 2026: about 114 a year and under 1% of all permits. 147 ADU and casita permits in the last 12 months (Oct 2025–Sep 2026), 79% more than the 82 in the 12 months before. The busiest month is September. The usual one took 167 days from issue to the county's final. 20817 has the most, 23.
Permits issued each month, October 2024 through September 2026.
| Month | Permits |
|---|---|
| Oct 2024 | 9 |
| Nov 2024 | 2 |
| Dec 2024 | 9 |
| Jan 2025 | 1 |
| Feb 2025 | 5 |
| Mar 2025 | 8 |
| Apr 2025 | 7 |
| May 2025 | 8 |
| Jun 2025 | 5 |
| Jul 2025 | 6 |
| Aug 2025 | 12 |
| Sep 2025 | 10 |
| Oct 2025 | 13 |
| Nov 2025 | 10 |
| Dec 2025 | 18 |
| Jan 2026 | 5 |
| Feb 2026 | 3 |
| Mar 2026 | 18 |
| Apr 2026 | 17 |
| May 2026 | 8 |
| Jun 2026 | 11 |
| Jul 2026 | 14 |
| Aug 2026 | 13 |
| Sep 2026 | 17 |
By calendar month, 100 = an average month (the thin line). September is the busiest (141), January the quietest (31). A busy month at the permit counter usually means a longer wait for a contractor.
| Month | Index |
|---|---|
| January | 31 |
| February | 42 |
| March | 136 |
| April | 126 |
| May | 84 |
| June | 84 |
| July | 105 |
| August | 131 |
| September | 141 |
| October | 115 |
| November | 63 |
| December | 141 |
Permits issued Oct 2024–Sep 2025, at least 12 months before the file ends. Usual days is the middle permit among the 62 with a final date.
| Measure | Value |
|---|---|
| Permits issued Oct 2024–Sep 2025 | 82 |
| Usual days, issue to final | 167 |
| Middle half, days | 85–307 |
The value written on the permit at application, from 223 permits with one. Not a quote and not the final bill.
| Measure | Value |
|---|---|
| Usual declared value | $40,000 |
| Middle half | $15,000–$135,000 |
Counted at the property's ZIP code. Share is the part of the county's 229 ADU and casita permits.
How the county filed these permits. We group its types into kinds of work; this is the split.
| Permit type | Permits | Share |
|---|---|---|
| Single Family Dwelling: alter | 151 | 66% |
| Single Family Dwelling: add | 50 | 22% |
| Residential Accessory Structure: construct | 14 | 6% |
| Townhouse: alter | 4 | 2% |
| Single Family Dwelling: restore and / or repair | 4 | 2% |
| Garage: construct | 3 | 1% |
| Residential Accessory Structure: alter | 1 | under 1% |
| Residential Accessory Structure: add | 1 | under 1% |
| Shed: construct | 1 | under 1% |
Electrical (22,023)HVAC (15,557)Solar (7,854)Remodels & repairs (2,673)Garages, sheds & shade structures (2,548)Additions (1,775)New homes (1,590)Pools & spas (258)
ADU and casita permits for other places in Washington, DC. Each permit office keeps its own file, so the numbers are not added together.
Arlington, VAWashington, DCFairfax County, VARockville, MDPrince George's County, MDHoward County, MD
Source: dataMontgomery: Residential Permit, Commercial Permits, Mechanical Permits and Electrical Building Permits (Department of Permitting Services), read 19 Oct 2026. We count permits issued October 2024 through September 2026; denied and withdrawn permits are left out.
Building, electrical and mechanical permits issued by the Montgomery County Department of Permitting Services, which covers the county outside the cities that run their own building offices: Silver Spring, Bethesda, Potomac, Germantown, Clarksburg, Chevy Chase, Olney, Wheaton, Takoma Park and the rest. The cities of Rockville and Gaithersburg issue most of their own building permits, so permits inside those cities are largely missing; a Rockville or Gaithersburg mailing address in this file is usually just outside those cities. Plumbing and gas-service permits are issued by WSSC Water, not the county, and are not in the file.
Counts are permits, not jobs: one job can need several permits. Nobody paid to be on this page and nobody can. Sources and definitions →
Free to reuse with attribution (CC BY 4.0). Please credit Contractor Records and link to this page. Suggested citation:
Contractor Records, "ADU and casita permits in Montgomery County, MD", https://contractorrecords.com/montgomery-county-md/adu-permits, data through September 2026, from Montgomery County Department of Permitting Services building-permit records.Link to a table: By month · Season · Days to final · Declared value · By ZIP code · Permit types.
Download the tables (CSV): ADUs & casitas permits by month · ADUs & casitas permits by calendar month (index) · ADUs & casitas permits: days to final · ADUs & casitas permits: declared value · ADUs & casitas permits by ZIP code · ADUs & casitas permits by permit type.