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Where can I put an accessory apartment in a principal dwelling in Washington, D.C.?

Accessory apartment in a principal dwelling

Allowed by right in 4 districts

What this does not cover

• 138,270 properties are loaded, county-wide. The District’s parcel record gives a street address but no ZIP code, so there is no ZIP breakdown to give and none is shown.
• A further 2,535 properties carry a parcel zone code this page cannot match to a single column of the use table: (none), ARTS (6 variants, e.g. ARTS-1;ARTS-2), BF (7 variants, e.g. BF-1A;RA-1), CG (6 variants, e.g. CG-3;RA-2), D (17 variants, e.g. D-2;D-6), HE (6 variants, e.g. HE-1;HE-2), MU (131 variants, e.g. MU-1/DC;MU-2/DC), NHR;PDR, NHR;UNZONED, NMU (16 variants, e.g. NMU-3A/MW;RA-1), NYE;UNZONED, PDR (34 variants, e.g. PDR-1/CAP;RF-1/CAP), R (58 variants, e.g. R-1A/CBUT;R-1B), RA (18 variants, e.g. RA-1;RA-2) and 5 more.
• 1,678 of those lie in TWO OR MORE districts at once. Their code below holds every district the parcel really shares area with, joined by a semicolon — ARTS-1;ARTS-2, ARTS-1;ARTS-4;RA-2, ARTS-1;RF-1, ARTS-3;ARTS-4, ARTS-3;RA-2 and 327 more. The ordinance does not say the larger share wins, so we do not pick one: the parcel is shown as straddling and is not counted under either district.
• (none) above means a parcel with no zone code assigned in the District's own data — 5 of them.
• Owner filters. We have an owner of record for 132,963 of Washington, D.C.’s 138,270 parcels, of which 36,467 are owned by a company, trust or other organization, including 6,282 owned by public bodies — governments, authorities, schools, churches. That split is Zonescore’s reading of the owner’s name, not something the District published, and we keep the two apart rather than deciding for you which counts as an investor. 19,115 have an owner whose mailing address is outside DC — read off the end of the District’s own address string, where the state actually is, because “MD” also occurs inside “RICHMOND”. We could read a state on 126,746 of them; the rest are not counted either way. 34,374 are owned by somebody this District writes to at a different address — not the property itself. That is where the tax bill goes, which is not the same as where the owner sleeps — an owner can collect mail at a property they rent out, and one who is written to elsewhere may still live here. We can tell you the two addresses differ; we cannot tell you the owner does not live at the property. 18,004 of them are written to an address inside DC, so the out-of-state filter above cannot see them at all. That count is out of the 117,932 properties where we could compare the two addresses. On 15,031 more we could not — the owner is written to a post-office box, or the District’s own record of the property names a street and no building number — and those are left out rather than counted as living at home. Matching two addresses is Zonescore’s reading, not something the District published: we treat “123 Main St” and “123 Main Street” as one place, ignore an apartment number, and compare the ZIP code rather than the town name — a jurisdiction’s record of a property and its record of that property’s owner often name the same place by different towns, and treating those as two addresses would count somebody living in their own house as an absentee. Owned for (based on the last recorded transfer): under 2 years 13,000+; 2-5 years 18,000+; 5-10 years 26,000+; 10-20 years 26,000+; 20-30 years 18,000+. 30+ years: Not offered here. The transfer dates we hold for the District begin in 1997, so they cannot show a 30-year hold. Older recorded transfers from the District would close this. 33,000+ properties have no transfer date we can read and are in no bucket. 70,693 are worth more as land than as building — the District’s own land assessment is at least 50% of its total. 5,241 properties carry no pair of assessments and are left out of that count rather than treated as zero, which would make every one of them look like bare land.

  Owner data from District of Columbia's property ownership records, retrieved September 25, 2026. CC BY 4.0.

• The parcel record we fetch carries no ZIP code for the property itself, so the district counts above carry no ZIP breakdown. It gives the street address only; the one ZIP it does carry belongs to the owner’s mailing address, which is a fact about a different place and is not used here. We do not infer a ZIP we were not given.
• Overlay districts are not modeled here. An overlay can change what a property allows.
• Some cells in this ordinance state two outcomes without saying what separates them; those are shown with their code and their source, and not guessed at.

Built from scripts/build_reverse_index.py, generated 2026-10-11T20:59:04+00:00.