Accessory dwelling unit cost — Cambridge, MA
Last updated: September 24, 2026
What affects the price
Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.
About this service
The total cost for an ADU depends on whether you are building a new detached structure, converting an existing garage, or adding an attached unit. Factors like plumbing installation, electrical panel upgrades, and custom interior finishes drive the final investment. Understanding these variables early helps you determine the feasibility of your project. Exact pricing confirmed free on the call.
Frequently asked in Cambridge
What are the requirements for a backyard accessory dwelling unit in Cambridge?
Are there specific ADU programs in New Hampshire?
What is involved in an accessory dwelling unit permit in Cambridge?
How do I find an accessory dwelling unit contractor in San Diego?
What are the options for accessory dwelling unit financing in Cambridge?
Where can I find accessory dwelling unit builders near me in Cambridge?
What are the considerations for accessory dwelling unit construction in Cambridge?
Also serving nearby: Newton · Boston · Quincy · Lynn · Brockton
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Cambridge — population 118,214; about 18,479 residents per square mile across 6.4 sq mi. ZIP codes covered include 02138, 02139, 02140, 02141, 02142, 02238.
Neighborhoods served in Cambridge: East Cambridge, The Port, Central Square, Inman Square, Wellington-Harrington — and every surrounding area.
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