Status: enacted July 7, 2026
Charles County's ADU rules are Bill 2026-06 / ZTA #25-189, "Flexibility for Accessory Dwelling Units" — passed unanimously on July 7, 2026 and now codified in the county code at §3.01.700 ("primary residence with accessory apartment"). What follows is the enacted text. Counties do amend their codes, so verify anything you're acting on with Planning & Growth Management at 301-645-0692.
Sources: Board of County Commissioners meeting highlights, July 7, 2026 (star983.com); codified text (ecode360.com §3.01.700); BOCC briefing packet, April 28, 2026.
Where ADUs are allowed
Under the enacted law: attached or detached ADUs are permitted with conditions in any district where single-family detached homes are allowed — including WC (Waldorf Central). An ADU does not count as a dwelling unit for density calculations. The law also adds townhouse ADUs in certain zones, but only in new projects with preliminary plan approval after the ordinance takes effect, capped at 35% of the principal unit's size.
Sources: Charles County Bill 2026-06 / ZTA 25-189 (enacted text, §§3.01.700.A, 3.02.210).
Size, bedrooms, height
Lots under 3 acres: up to 1,000 square feet or 75% of the main home's floor area, whichever is smaller.
Lots of 3 acres or more: up to 75% of the main home's floor area, no absolute cap.
Bedrooms: maximum 2, and never more than the main house has.
One ADU per lot — a lot may not have both an attached and a detached ADU.
Height: at most 2 stories or 24 feet, never above the district maximum. An ADU cannot be a mobile home. No fixed minimum size — the old 300-square-foot floor was deleted.
Sources: Charles County Bill 2026-06 / ZTA 25-189 (enacted text, §§3.01.700.F, G, H).
Setbacks and placement
Attached ADUs meet the same setbacks as the main house. Detached ADUs on lots under 3 acres: meet the zone's front setback, sit at least 6 feet behind the main home's front building line, keep 6 feet to side and rear lot lines, keep 6 feet from other buildings, and never build inside a recorded easement. Detached on 3+ acres: can go anywhere but must stay 50 feet from any public road right-of-way. Attached-ADU entries and stairs must not be visible from the street.
Sources: Charles County Bill 2026-06 / ZTA 25-189 (enacted text, §§3.01.700.E, I; §297-29.B).
Parking: zero required
The law amends the parking table to read "NO OFF-STREET PARKING SPACES REQUIRED" for ADUs. That matches the state law's direction and goes beyond it. (Townhouse ADUs are the exception, with their own formula.)
Sources: Charles County Bill 2026-06 / ZTA 25-189 (enacted text, amending Art. XX §297-335).
The permit order (this part matters)
Under the enacted law, the health department must approve your water supply and sewage disposal BEFORE any ADU or building permit issues — septic first, paperwork second. Then a dedicated Accessory Dwelling Unit Permit from the zoning administrator is required before any building permit or excavation. Get the order wrong and you redo steps. Our permit step-by-step guide walks the full sequence with the real fee schedule.
Sources: Charles County Bill 2026-06 / ZTA 25-189 (enacted text, §§3.01.700.D, J); new Art. XXVI §297-430.E.
What the draft does NOT include
No owner-occupancy requirement appears in the current code or the enacted text — we searched the full text. HOAs: the ordinance has no HOA provision, but county staff's stated position is "HOA guidelines apply" — the county will not overrule your covenants. Timelines: the county publishes no permit review timeline — treat any timeline promise as unconfirmed. Excise tax: the Fair Share Excise Tax rate and any ADU exemption are unverified.
Sources: Charles County Bill 2026-06 / ZTA 25-189 (ena cted text, full-text search); Charles County staff briefing, April 28, 2026.