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ADU Cost Guide · Comparing Options

ADU, Addition, or Finished Basement?

Three ways to add space to your property — what each costs, what each earns, and which one fits your actual goal. No invented numbers, just the real trade-offs.

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

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Not sure which path fits? Tell us your goal — we will point you at the right one, even if it is not an ADU.

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Couple touring a bright finished ADU interior

The three paths, side by side

A detached ADU is a separate small home on your lot. Highest total cost (Makara ADU publishes $150,000–$350,000 for a detached build), but it is the only option that creates a fully independent dwelling — own entrance, own kitchen, own meter potential — which is what makes long-term rental income real. Zoning rules apply: size caps, setbacks, and permits.

A home addition expands your existing house — a new bedroom wing, a bigger kitchen, a second story. Cost lands between a conversion and a detached ADU for comparable space, and it is the most straightforward path when the goal is your own family's comfort. It rarely creates rental income (it is still one house), and it changes your home's footprint, which can trigger its own zoning review.

A finished basement is the cheapest square footage you will ever buy — the structure already exists. But basements have limits: ceiling height, egress windows for bedrooms (a code requirement), moisture control, and in many counties, a basement apartment still needs ADU approval to be a legal separate dwelling. See basement ADUs.

Sources: Makara ADU (quoted in The Banner, detached range).

Match the path to the goal

Rental income? The detached ADU wins — independence is what tenants pay for. An addition does not create a rentable unit; a basement can, but only with proper egress and ADU approval.
Aging parents nearby? Any of the three can work. An ADU for aging parents gives independence; an addition keeps everyone under one roof; a basement is cheapest but stairs are the enemy of aging in place.
More space for your kids? Addition or finished basement — you do not need a separate dwelling for your own family, and the ADU's rental premium buys you nothing.
Home office? A detached office ADU beats a basement desk for focus, but a finished basement corner costs a fraction.

The zoning wrinkle

Here is what surprises people: in Maryland, the ADU often has the clearest legal path of the three. Chapter 197 of the 2025 Laws of Maryland made ADUs a by-right use with a 90-day ministerial decision — while additions and basement apartments still go through each county's standard review. The ADU is the new, purpose-built lane; the others are the old roads.

Sources: Chapter 197 of the 2025 Laws of Maryland (HB 1466/SB 891), §§4-504(A)(1), 4-505.

A note on prices: material costs move up and down, and no two lots need the same work. Treat any numbers on this page as starting points, not quotes. Your written estimate after our free lot walk is the real number for your project.

Questions homeowners ask us

Which adds more value: an ADU or a home addition?

It depends on what value means to you. An addition adds living space to your home; an ADU adds a separate dwelling that can earn rental income. For pure resale, appraisers treat them differently and local markets vary — we do not publish appreciation claims. For income, the ADU is the only one of the three that creates it.

Is a finished basement cheaper than an ADU?

Almost always, for raw square footage — the structure exists. But a basement is not automatically a legal ADU: bedrooms need egress windows, moisture must be controlled, and many counties require ADU approval for a separate dwelling unit. Cheap space and legal rental space are different things.

Can I rent out a home addition?

An addition is part of your house, not a separate dwelling — renting part of your home is roommate territory, legally and practically. If rental income is the goal, you want the ADU's independence: own entrance, kitchen, and bath.

Which option is fastest?

Usually the finished basement (no new structure), then the addition, then the detached ADU. But permits set the pace as much as construction — Maryland's 90-day ministerial rule for ADUs can make the ADU's permit path surprisingly competitive.

I just need space for my kids. Should I still consider an ADU?

Probably not — and we will tell you that. An addition or finished basement serves a growing family for less money and less permitting. Save the ADU for when you want independence on the lot: parents, adult children, or rental income.

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.

Not sure what fits your lot? Ask us.

One call settles it — we will tell you what your property can hold and what it would take.

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Every town below gets the same free lot walk and written estimate.

ADU Builders in La Plata, MD
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