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New Maryland law
Basement apartments and ADUs
Maryland now requires every county to allow accessory dwelling units, including basement conversions. A legal basement unit starts with legal egress.
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What changed
Maryland's ADU law required every county and city to adopt rules allowing accessory dwelling units on single-family lots by October 1, 2026. That includes units created by converting a basement.
Howard County's new ADU law took effect on April 8, 2026 and specifically lists townhome basement units and in-law suites. Montgomery County already allowed accessory apartments. Other counties are publishing their rules now.
Planning to rent the unit out? Read your county's ADU rules before you build. I'll take care of the exits.
Where egress comes in
An in-law suite or rental unit in the basement still has to meet building and fire codes. Every bedroom needs an emergency escape opening, and many units benefit from a separate entrance.
- Egress windows for each basement bedroom
- Egress doors and areaway stairs for a private entrance
- Basement finishing, from framing to a full bathroom
- One crew from planning through inspection
Free assessment
Not sure your basement can become a legal unit? We'll look at ceiling height, exits and light, and tell you what it would take.
Questions
ADU questions
Can I rent out my basement apartment?
That depends on your county's ADU rules. Some, like Howard County, have proposed owner-occupancy requirements. Check with your county planning office before you build.
Does a basement apartment need its own exit?
Each sleeping room needs an emergency escape opening, and the unit needs a safe way out. An egress window, egress door or walkout often solves both.