Residential ADU and addition permits in Baltimore County, MD
28 residential ADU and addition permits issued by Baltimore County (building), Baltimore County (electrical), the 8 weeks ending Oct 17, 2026. Oct 17, 2026 is the latest issue date the source has published.
Quick answer. In the 8 weeks ending Oct 17, 2026, 28 residential ADU and addition permits were issued in Baltimore County, MD, according to public records from Baltimore County (building), Baltimore County (electrical). The busiest ZIP codes were 21093 (4 permits), 21228 (3 permits), 21236 (3 permits). The median declared value was $59,428 across 16 permits that list one. The latest permit date published is Oct 17, 2026.
What an ADU and addition permit means in Baltimore County
A residential ADU or addition permit is a new unit or more square footage on an existing home. For an ADU builder or addition contractor it shows where lots are being built out, and the subs those jobs need.
In Baltimore County, permits were issued on 23 different days in the window; the most recent were Oct 15, 2026, Oct 14, 2026, Oct 13, 2026. The busiest ZIPs were 21093 (4), 21228 (3), 21236 (3).
By residential ADU and addition permit count, Baltimore County ranks #27 of the 46 ADU and addition pages on this site and #3 of 4 in MD.
- Mail the neighbors of each ADU.
- Pitch trades to the builders pulling the most permits.
- Track declared values by ZIP.
Other work on the same permits
Share of these 28 permits whose type or description also matches another trade. These are the follow-on and partner trades on Baltimore County jobs.
- electrical: 11 permits (39%)
- deck/patio: 4 permits (14%)
- garage: 1 permits (4%)
- windows & doors: 1 permits (4%)
Weekly trend
Permits per 7-day period, ending Oct 17, 2026. n/c = not collected yet (before our pipeline started pulling this source). It is not zero. Striped bars are partly collected weeks.
Top permit types
| Permit type / subtype | Permits | Share |
|---|---|---|
| Residential Alteration/Addition / Res. Permit - Alteration/Addition SFD | 13 | 46% |
| RESIDENTIAL ELECTRICAL | 11 | 39% |
| Residential Alteration/Addition / Res. Permit - Alteration/Addition RURAL RESIDENTIAL SFD | 3 | 11% |
| Residential Alteration/Addition / Res. Permit - Alteration/Addition AGRICULTURE | 1 | 4% |
Busiest ZIP codes
| ZIP | Permits | Share | 8-wk avg / week |
|---|---|---|---|
| 21093 | 4 | 14% | 0.50 |
| 21228 | 3 | 11% | 0.38 |
| 21236 | 3 | 11% | 0.38 |
| 21234 | 2 | 7% | 0.25 |
| 21221 | 2 | 7% | 0.25 |
8-wk avg / week is the trailing 8-week weekly average we quote in coverage checks for that ZIP and trade. It counts every source in the ZIP and includes permits with unknown use, so it can be higher than this page's residential count.
Type stated in the permit
| Type | Permits | Share |
|---|---|---|
| room addition | 26 | 93% |
| second story | 2 | 7% |
Parsed from the permit's own type and work text. A permit can state more than one; many state none.
Sample rows
Anonymized: street address, permit number and any names removed. Subscribers get the full row with address, permit number and source link.
| Issued | ZIP | Permit type | Scope | Type | Declared value |
|---|---|---|---|---|---|
| 2026-10-15 | 21057 | Residential Alteration/Addition / Res. Permit - Alteration/Addition RURAL RESIDENTIAL SFD | addition/ADU | room addition | $35,000 |
| 2026-10-12 | 21236 | Residential Alteration/Addition / Res. Permit - Alteration/Addition SFD | addition/ADU + deck/patio | room addition | $115,928 |
| 2026-10-02 | 21136 | RESIDENTIAL ELECTRICAL | electrical + addition/ADU | room addition | n/a |
| 2026-09-25 | 21093 | Residential Alteration/Addition / Res. Permit - Alteration/Addition SFD | addition/ADU | room addition | $5,750 |
| 2026-09-22 | 21133 | Residential Alteration/Addition / Res. Permit - Alteration/Addition SFD | addition/ADU | room addition | $6,000 |
| 2026-09-11 | 21136 | RESIDENTIAL ELECTRICAL | electrical + addition/ADU + garage | room addition | n/a |
Source
- Baltimore County (building): Permit records on bcgisdata.baltimorecountymd.gov, published by Baltimore County (building). Source dataset. Collected window(s): Aug 22, 2026 – Oct 16, 2026. Last pulled Oct 18, 2026.
- Baltimore County (electrical): Permit records on bcgisdata.baltimorecountymd.gov, published by Baltimore County (electrical). Source dataset. Collected window(s): Aug 23, 2026 – Oct 17, 2026. Last pulled Oct 18, 2026.
Metric: Residential = the source marks the permit's use as residential (permits with commercial or unknown use are not counted). ADUs & Additions = the permit's type or work description matches the Curbside Signal ADU and addition rules. Counts exclude void or cancelled permits. Dates are the jurisdiction's permit issue date. Records are deduplicated on source and permit number. How we count. Part of the Baltimore-Columbia-Towson, MD metro: every trade × city page there.
The honest limit. A permit usually means the job is already sold. We say that up front. The value is what happens around it:
- Neighbor marketing around active jobs: same-age houses on the same street.
- Cross-trade follow-on demand: new roof → solar, gutters, insulation; remodel → HVAC, electrical, landscaping, pool; new build → pest, security, landscaping.
- Competitor intelligence: which contractors pull permits where (where the jurisdiction publishes it), and who to recruit as subs.
- Early-stage projects for commercial trades and GC subs.
Follow-on: ADUs and additions drive HVAC, electrical, plumbing, solar and landscaping work.
Other trades in Baltimore County, MD
Residential permits in the same window, by trade.
Questions
How many residential ADU and addition permits were issued in Baltimore County, MD recently?
28 residential ADU and addition permits in the public records we pulled, the 8 weeks ending Oct 17, 2026. Source: Baltimore County (building), Baltimore County (electrical).
Which Baltimore County ZIP codes have the most ADU and addition permits?
21093 (4 permits), 21228 (3 permits), 21236 (3 permits), by residential ADU and addition permit count the 8 weeks ending Oct 17, 2026. 16 ZIP codes had at least one permit.
What is the median declared value of a residential ADU and addition permit in Baltimore County?
$59,428, across 16 permits that list a valuation. Declared values are what the applicant stated on the permit, not the contract price.
How do I get the Baltimore County ADU and addition permit list, and what does it cost?
Request a free sample for your ZIPs first. ZIP Pack is $29/mo for one trade and up to 5 ZIPs every Monday; Metro Feed is $99/mo for a whole metro and up to 3 trades, with daily alerts. Guarantee on every package: If a weekly file is late or missing, that month is free. If a month delivers under half the 8-week average permit count for your ZIPs and trade, the next month is free.
Baltimore County ADU and addition leads, every Monday
Send your trade and ZIP codes. We'll reply with a real sample from the public records we pull, or tell you plainly that we don't cover you yet.