Full-Service ADU Construction
Design. Permits. Build. One Team From Start to Finish.
Calculate The Cost of Your ADU
Ready to see what an ADU would cost for your home? Use our free calculator to learn more.
Calculate The Cost of Your ADU
Ready to see what an ADU would cost for your home? Use our free calculator to learn more.
Get A Free Quote For Your ADU
Keep Family Close
Create a private, fully independent living space for a parent or grandparent without sacrificing privacy.
Create AirBnB Income
Turn unused space into a short-term rental designed for comfort, durability, and long-term returns.
Build for Long-Term Renting
Add a compliant, high-quality rental unit that increases property value and generates consistent monthly income.
Why Homeowners Choose Republic Building Contractors
- ADU specialists
- Fully licensed and insured
- Local zoning and permitting expertise
- Transparent pricing and clear timelines
- One point of contact from design to completion
What Is an Accessory Dwelling Unit (ADU)?
An Accessory Dwelling Unit (ADU) is a fully independent living space built on your existing residential property. ADUs can be attached to your home, detached as a separate structure, or created through garage or basement conversions.
ADUs are commonly used for:
In-law suites or multi-generational living
Rental income or Airbnb opportunities
Guest houses or private home offices
Increasing property value without moving
We help you determine what is allowed, what makes financial sense, and how to build it correctly the first time.
Calculate The Cost of Your ADU
Ready to see what an ADU would cost for your home? Use our free calculator to learn more.
Calculate The Cost of Your ADU
Ready to see what an ADU would cost for your home? Use our free calculator to learn more.
How Our Process Works
Plan & Approve
We review your property, confirm zoning and feasibility, and create a clear ADU plan with realistic pricing and timelines.
Design & Permit
Our team handles architectural design, engineering, and all permitting so everything is approved before construction begins.
Build & Deliver
We construct your ADU from the ground up, manage inspections, and deliver a move-in-ready space with a final walkthrough.
Full-Service ADU Design & Construction
Most ADU projects fail because homeowners are forced to coordinate designers, engineers, and contractors themselves. We eliminate that risk.
Republic Building Contractors is a true design-build ADU contractor. That means we manage the entire process under one roof.
Our ADU Services Include:
Feasibility and zoning review
Architectural design and engineering
Permit management and approvals
Site preparation and utilities
Full construction and inspections
Final walkthrough and close-out
One team. One contract. One partner.
ADU Options We Build
Not sure what works for your property? We will walk you through your best options during your consultation.
Detached ADUs
Standalone units built on your property, ideal for rentals, privacy, or long-term income.
Attached ADUs
Connected additions that blend seamlessly with your existing home.
Garage Conversions
Transform underused space into a fully functional living unit.
Frequently Asked Questions
If you’re thinking about building an accessory dwelling unit (ADU), you’ll likely have questions. The experienced team at Republic Building Contractors is here to answer them!
How much does ADU construction cost?
There is no standard cost for an accessory dwelling units. The cost of ADU construction depends on its size, layout, finishes, and site conditions. To learn more about pricing, try our Cost Calculator by clicking here.
How long does an ADU take to build?
It won’t be long until your brand-new ADU is ready for its first residents or guests! The average time it takes to build an ADU including permitting is 6-9 months although that range can be adjusted by things like permitting, weather or design changes.
Do you handle permits and zoning?
Yes, Republic Building Contractors take care of everything! We know how daunting it can be to worry about permits and zoning on top of planning your new accessory dwelling unit. Rest assured, we manage the entire permitting process from start to finish and ensure compliance with local regulations.
Can my ADU be used as a rental or Airbnb?
In many cases, your accessory dwelling unit can be used as a rental or Airbnb however each town or city may have it’s own rules and regulations.
What does an accessory dwelling unit contractor do?
All ADU builders are not “built” the same! Here at Republic Building Contractors, our team handles design, permitting, construction, and compliance with local zoning codes. We also manage all subcontractors, such as plumbers and electricians, and provide a clean finished space ready for occupancy.
Should I build a detached or attached ADU?
Whether you build a detached or attached ADU ultimately depends on your goals, needs, and budget. Many homeowners build an attached accessory dwelling unit because it generally costs less. However, others build a detached one because it offers more privacy, higher rental income, and greater property value.
If you’re unsure which ADU construction option to consider, we’re available to discuss the pros and cons of each option with you.
Are accessory dwelling units allowed on my property?
As of early 2025, accessory dwelling units are allowed ‘by right’ on single-family lots in Massachusetts. This means that you don’t need a zoning variance or a special permit to build one. However, you must still comply with local building codes.
What is the largest ADU I can build?
The maximum size for an ADU in Massachusetts is 900 square feet, or 50% of the principal dwelling's gross floor area, whichever is smaller. If you’re building an internal ADU, it’s within the existing footprint of your home, so no floor area is added.
Ready to Build Your ADU?
If you are considering an ADU, the first step is understanding what is possible for your property. Schedule a free consultation with Republic Building Contractors and get clear answers, realistic timelines, and expert guidance.