Full-Service ADU Construction: Design, Permits, and Build Under One Roof
Republic Building Contractors is a design-build ADU contractor that manages the entire accessory dwelling unit process from initial planning through final inspection. Rather than leaving homeowners to coordinate separate designers, engineers, and contractors, they handle everything under one contract and one team.
Their services cover feasibility and zoning review, architectural design and engineering, permit management, site preparation, utilities, full construction, inspections, and a final walkthrough. This approach is intended to reduce the coordination burden that often causes ADU projects to stall or go over budget.
What Is an Accessory Dwelling Unit (ADU)?
An accessory dwelling unit is a fully independent living space built on an existing residential property. ADUs can take several forms:
- Detached ADUs — standalone structures built separately on the property, often used for rentals or to provide privacy
- Attached ADUs — additions connected to the existing home
- Garage conversions — transforming underused garage space into a functional living unit
Common uses for ADUs include in-law suites or multi-generational living arrangements, long-term rental income, short-term rentals such as Airbnb, guest accommodations, and increasing overall property value. Republic Building Contractors works with homeowners to determine what type of ADU is feasible for their specific property and goals.
As of early 2025, ADUs are permitted by right on single-family lots in Massachusetts, meaning no zoning variance or special permit is required. However, local building codes still apply. The maximum ADU size in Massachusetts is 900 square feet, or 50% of the principal dwelling's gross floor area, whichever is smaller.
How the ADU Building Process Works
Republic Building Contractors follows a structured three-phase process:
- Plan & Approve — They review the property, confirm zoning and feasibility, and establish a clear plan with pricing and timelines.
- Design & Permit — Their team manages architectural design, engineering, and all permitting before construction begins.
- Build & Deliver — Construction is carried out, inspections are managed, and the completed unit is handed over with a final walkthrough.
Republic Building Contractors is fully licensed and insured, and they provide a single point of contact throughout the project. They also manage all subcontractors, including plumbers and electricians, so homeowners are not left to coordinate trades on their own.
Regarding timelines, the average ADU project — including permitting — takes approximately 6 to 9 months, though this can vary depending on permitting timelines, weather conditions, and design changes. Costs vary based on size, layout, finishes, and site conditions, so there is no fixed standard price for an ADU build.
For homeowners considering whether to build a detached ADU or an attached one, the choice generally comes down to budget, privacy needs, and long-term goals. Attached units tend to cost less, while detached units often offer greater privacy and potentially higher rental income.
Republic Building Contractors offers free consultations to help homeowners understand what is possible on their property, what the realistic costs and timelines look like, and which ADU option best fits their situation.
