Statewide ADU Construction
ADU Builder in Maryland
Maryland’s ADU Act opened the door statewide. We design, permit, and build accessory dwelling units across Anne Arundel County and the surrounding region — detached units, garage and basement conversions, attic conversions, and in-law suites.
An accessory dwelling unit is a second, self-contained home on a property that already has a house — its own kitchen, bathroom, and entrance. Marylanders build them to house aging parents or adult children, to generate rental income, or to add long-term value to a lot they already own.
The ADU Builder is the accessory dwelling unit division of Madrid’s Contracting, a family business with more than 35 years of residential construction in Anne Arundel County. We handle design, permitting, and construction start to finish, so you deal with one contractor rather than coordinating an architect, an expediter, and a builder yourself.
Where We Build in Maryland
Our work is concentrated in Anne Arundel County, where the county passed its own ADU ordinance in 2023 and the permitting path is well established. We regularly build in Annapolis, Glen Burnie, Pasadena, Severna Park, Crofton, and Odenton, and take projects in neighboring communities across the county.
Because we have been building in this county for three decades, we know the inspectors, the plan-review process, and the practical realities of these lots — septic versus public sewer, older housing stock, waterfront setbacks, and HOA restrictions that vary street to street.
What Maryland's ADU Act Changed
Maryland’s statewide ADU Act (SB 891 / HB 1466) took effect October 1, 2025. It requires counties and municipalities to allow accessory dwelling units by right on lots zoned for single-family residential use, replacing outright bans and discretionary hearings with a defined permitting path. Local governments can still set reasonable standards for size, setbacks, and parking.
Anne Arundel County was ahead of the state on this, with its own ADU ordinance (Bill 6-23) already in place since 2023. For what each law requires and how they interact, read our full guide to Maryland ADU law.
What a Maryland ADU Costs
Most Maryland ADU projects fall between $80,000 and $300,000+, depending on type. Conversions of existing space — a garage, attic, or basement — sit at the lower end because they reuse an existing structure and foundation. Detached new construction sits at the upper end but offers the most flexibility. Our Maryland ADU cost guide breaks this down by type, including how hard and soft costs divide and what drives a quote up or down.
Maryland ADU Questions
Are ADUs legal everywhere in Maryland?
Since October 1, 2025, counties and municipalities must allow ADUs by right on single-family-zoned lots under the state ADU Act. Local standards for size, setbacks, and parking still apply and vary by jurisdiction, so what you can build in Anne Arundel County may differ from a neighboring county.
Can I rent out an ADU in Maryland?
In most cases yes, and rental income is one of the main reasons homeowners build them. Some jurisdictions attach owner-occupancy conditions to the main house or the unit, and HOA rules can add their own restrictions, so confirm the requirements for your specific address before counting on rental income.
How long does a Maryland ADU take to build?
Design and permitting typically run a few months before construction starts, and build time depends heavily on type — a basement or garage conversion moves faster than detached new construction, which involves foundation, utilities, and full exterior work. We give you a realistic schedule at the consultation rather than an optimistic one.
Start Your Maryland ADU Project
Every project starts with a free, on-site consultation and a real number. Call (410) 755-7663 or request a consultation and we will walk your property, talk through what your lot allows, and give you an honest assessment of what it will take.