ADU Builders in Waldorf, MD

We design and build backyard cottages, garage conversions, and in-law suites across Charles County — drawn for your lot, permitted with the county, and priced in writing before we start.

Free on-site estimates · No-pressure advice · Waldorf and Charles County, MD

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Tell us about your lot — we will tell you what fits and what it costs.

What is an ADU?

An ADU — accessory dwelling unit — is a small, complete home on the same lot as your main house. It has its own kitchen, bathroom, bedroom, and entrance. People call them backyard cottages, in-law suites, granny flats, or garage apartments. The idea is the same: a second front door on land you already own.

Why Waldorf homeowners build them

Multigenerational living, with privacy intact. An aging parent gets her own kitchen and front door, twenty steps from your back door — not twenty minutes across town.
Rental income from your own land. A one-bedroom cottage in Charles County can rent for real money every month, paying down your mortgage while you sleep.
Room for a grown kid or a caregiver. Cheaper than an apartment, closer than a facility, and it adds value to your property either way.
A home office that is actually separate. Close the cottage door at 6pm and work stays at work.

What kinds of ADUs we build

An accessory dwelling unit can take several forms. Here are the five we build most:

Detached backyard cottages — a brand-new small home in your backyard, from studio to two bedrooms.
Garage conversions — your existing garage becomes a finished apartment with heat, plumbing, and a kitchen.
Attached in-law suites — an addition connected to your house with its own entrance.
Basement apartments — a legal second unit below your main living space, done to code.
Above-garage units — living space over a detached garage, a smart use of a structure you already have.

ADU styles, up close

Every lot is different, so we build four ways. Here is what each one looks like:

Detached backyard cottage ADU glowing at dusk — **Detached cottages**A brand-new small home in your backyard, from a studio to two bedrooms — drawn for your lot's shape and slope. See detached ADUs ›

Bright finished interior of a garage conversion apartment — **Garage conversions**Your garage becomes a legal one-bedroom apartment with a kitchen and bath — the fastest, most affordable way in. See garage conversions ›

Bright in-law suite bedroom with a wide doorway — **In-law suites**An addition with its own entrance, built for a parent who wants independence twenty steps away.

Cozy finished bedroom inside a backyard cottage — **Basement apartments**A legal second unit below your main floor — finished to the same standard as the rest of the house.

What the inside can look like

Small does not mean cramped. Here is what a finished ADU interior can look like — real kitchens, real bedrooms, real daylight.

Modern small kitchen with white cabinets inside a backyard cottage — Example: a full kitchen with gas range and real cabinets.

Bedroom and sitting area inside a finished backyard cottage — Example: a bedroom and sitting area in a finished cottage.

Open living area inside a converted garage apartment — Example: open living space in a finished garage conversion.

Finished backyard cottage exterior — Example exterior: a cottage designed to look like it always belonged there.

Smiling couple standing in front of their new backyard cottage — Example: a finished cottage in the backyard.

Couple relaxing on the porch of their backyard cottage at dusk — Example: a cottage porch at dusk.

How the county side works

Charles County decides what you can build: how big, how tall, how far from the property line, and what permits you need. Maryland's 2025 accessory dwelling unit law (Chapter 197 of the Laws of Maryland) pushed counties to make approvals simpler, but the local rules still matter lot by lot. We handle the zoning check, the permit drawings, and the county filings for you — it is part of the job, not an extra.

Built by a crew, not a call center

Construction crew raising the framed walls of a backyard cottage

Framing day is the best day on any build — the day a flat foundation starts looking like somebody's home.

One project manager runs your job from framing to finishes. Deep remodeling know-how, one number to call, and a final walkthrough of every room before we call the job done.

What it costs (honestly)

A garage conversion usually costs less than a new detached cottage, because the walls and roof already exist. A new cottage costs more, but gives you a fully separate home. The range is wide, which is exactly why we do free on-site estimates: after we walk your lot, you get a written price for your project, not a national average from the internet.

A note on prices: any numbers you see on this website can change — lumber, concrete, and fixture costs move up and down, and no two lots need the same work. Treat them as starting points, not quotes. Your written estimate after the free lot walk is the real number for your project.

ADU rules are changing right now

Last updated: October 1, 2026. Three county decisions are in motion that could change what homeowners can build:

Prince George's County moved its ADU bill (CB-74) through committee in September 2026 — state law required the county to adopt ADU rules by October 1, 2026. We are watching for the final vote.
Montgomery County is working through changes to match Maryland's 2025 ADU law (ZTA 26-06) — outcome still pending.
Montgomery County, Bill 41-26 — a hearing on October 6, 2026 could remove the county's owner-occupancy rule, which would let a homeowner rent out both the main house and the ADU.

We update this page as each decision lands. Call us and we will tell you where the rules stand for your lot.

Sources: Maryland General Assembly — Chapter 197 of the 2025 Laws of Maryland (HB 1466/SB 891); Prince George's County Council legislation (CB-74); Montgomery County Council (ZTA 26-06, Bill 41-26).

What homeowners say

"They turned our unfinished basement into a real apartment for my mother. The crew was clean, the price never moved, and the county paperwork was handled start to finish."

— Denise W., Charles County, MD · basement remodel

"We added a master suite onto the back of our ranch. Fifteen years of remodeling experience shows — they caught problems our first contractor missed and fixed them without drama."

— Marcus T., Charles County, MD · home addition

"Full kitchen and bath remodel. Done on the schedule they promised, and the final walkthrough caught every little thing before we paid the last dollar."

— Angela R., Charles County, MD · kitchen & bath remodel

Questions homeowners ask us

How long does it take to build an ADU in Waldorf?

A garage conversion often takes 8–12 weeks once permits are issued. A new detached cottage usually takes 4–7 months from permit to move-in. The county permit review itself can add several weeks, which is why we file early and follow up often.

Can I rent out my ADU in Charles County?

In most cases, yes — long-term rental of an ADU is allowed, though some zoning districts have owner-occupancy rules meaning you must live in either the main house or the ADU. We check your specific zoning before you commit to anything.

Will an ADU raise my property taxes?

Usually, yes — added living space raises your assessed value. Whether the extra tax is worth it depends on your plan: rental income, housing a parent, or avoiding assisted-living costs. We can talk through the math at your visit.

Do I need a separate address or mailbox for the ADU?

Often a separate mailing address helps with utilities and deliveries. We walk you through what the county and post office need during the permit process.

What if my HOA says no?

Some HOAs restrict ADUs even where the county allows them. Bring us your HOA covenants at the first visit and we will read them with you before you spend a dollar.

How much does an ADU cost in Maryland?

A garage conversion often starts in the low six figures. A new detached cottage usually runs several hundred thousand depending on size and finishes. But material prices move and every lot is different — treat numbers on this page as starting points, not quotes. Your written estimate after our free lot walk is the real number for your project.

Are ADUs legal in Maryland?

Yes. Maryland's 2025 ADU law (Chapter 197 of the Laws of Maryland) requires counties to allow accessory dwelling units under reasonable rules, and it overrode the strictest local bans. Each county still sets its own size, setback, and permit requirements, so we check your lot's zoning before anything else.

What is the difference between an ADU and an in-law suite?

An in-law suite is one kind of ADU — usually an attached addition or converted space with its own entrance. ADU (accessory dwelling unit) is the umbrella term. It also covers detached backyard cottages, garage conversions, and basement apartments.

What happens after you reach out

No mystery, no sales script. Here is the whole path from first call to move-in day.

1You reach outCall or send the form. Tell us about your lot and what you want the space for — a parent, rental income, a home office.

2We walk your propertyFree visit. We check setbacks, access, slope, trees, and utilities, and tell you honestly what fits.

3You get a plan and a priceA site plan and a written estimate for your lot. No pressure, no obligation, no fine print.

4Permits, then buildWe handle the Charles County paperwork and follow-ups. Then our partner builders build it.