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
Permit fees are paid to your local municipality and fluctuate based on the specific city or county where your property is located. These costs cover plan reviews, impact fees, and safety inspections required to make your new space legal and compliant. Because every jurisdiction has a different fee structure, the final amount depends on your specific town’s regulations. We help you estimate these during the planning phase. Exact pricing confirmed free on the call.
Frequently asked in Cambridge
What are the options for 24-hour ADU services?
What are accessory dwelling unit homes?
Accessory dwelling unit homes are secondary housing units built on the same lot as a primary residence in Cambridge. These can be detached structures, like backyard cottages, or attached units carved out from existing living space. They are designed to be fully independent living spaces, offering flexibility for extended family, rental income, or aging in place, all while adhering to city zoning and building codes.
What is an ADU unit?
An ADU unit, or accessory dwelling unit, is a self-contained secondary living space on a single-family property. It includes essential amenities like a bedroom, bathroom, and kitchen facilities, separate from the main house. In Cambridge, ADUs are subject to specific regulations regarding size, placement, and design to ensure they are integrated appropriately and comply with local zoning ordinances.
What are homes with mother-in-law suites?
Homes with mother-in-law suites, commonly referred to as accessory dwelling units (ADUs), are properties that feature a secondary, independent living space alongside the primary residence. These suites offer privacy and autonomy for residents and can be designed as detached structures, attached additions, or converted portions of the main house in Cambridge. They are a popular solution for multigenerational living or generating rental income.
What is a modular accessory dwelling unit?
A modular accessory dwelling unit (ADU) is constructed in sections within a factory setting and then transported to your Cambridge site for final assembly. This method often allows for quicker installation timelines and more predictable costings compared to traditional on-site construction. It is imperative that these modular units comply with all state and local building codes and zoning regulations applicable to ADUs.
What does an ADU builder do?
An ADU builder is responsible for the physical construction of an accessory dwelling unit in Cambridge. This includes managing all aspects of the building process, from site preparation and foundation laying to framing, utility installations, and interior/exterior finishing. They ensure the project adheres to architectural plans, building codes, and city regulations, delivering a completed, functional ADU.
What is an accessory dwelling unit contractor?
An accessory dwelling unit contractor oversees the entire construction process for your ADU in Cambridge. This includes managing subcontractors, procuring materials, ensuring adherence to architectural plans and building codes, and maintaining project timelines and budgets. They are responsible for the physical build, from foundation to finishes, and work closely with homeowners and city inspectors to guarantee a compliant and high-quality final product.
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: Harvard Square, Central Square, Inman Square, Kendall Square, Porter Square, East Cambridge — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Fairfield · Murrieta · Richmond · Vallejo
