Construction
Overview
- Get bids
- Hire a contractor
- Understand everyone’s roles during construction
Permit in hand, you’re ready to break ground and see your project become a reality! From site preparation to passing your final inspection, you’ll stay in touch with your contractor and make final decisions about project details.
Project Timeline
The Construction phase typically takes 6-12 months. Most ADU projects take 12-18 months to complete, but some extend to 24 months or more.
FAQs
When is my ADU ready for move-in?
Municipalities require both final inspections and a Certificate of Occupancy. Once the inspection is complete and the certificate issued, your ADU is ready for move-in—just be sure utilities are connected, an address is assigned, and all final preparations are in place.
See our blog post about renting your unit for more details about renting out the unit to long-term tenants. If moving friends or family into the unit, it’s still highly important to have a written agreement. Consult a lawyer or find an agreement template by searching online for phrases like “family rental agreement.”
How long does construction take?
Traditional construction will take 6-12 months, though this will vary depending on the specifics of the project. Stages of construction include:
- Prepping site & foundation: 1–2 months
- Framing & exterior: 1–2 months
- Systems & insulation: 1–2 months
- Finishes & final inspection: 1–2 months
Modular construction can take 4-6 months for materials to be ordered and completed in a factory, and another 4-8 weeks for finishing. State law requires licensing for manufactured housing.
How much does construction cost?
Construction costs (also called “hard costs”) for your ADU will vary significantly depending on personal preferences, site conditions, location, and many other factors. Hard costs typically total around 85% of your total project budget.
See the budgeting page for more details.
How do I find a contractor?
If you are not using a design/build firm, you will need to find a contractor to take over for the construction phase of your ADU.
First, you’ll solicit bids from potential contractors. You will want to get at least three bids for comparison and judge them based on completeness, experience, references, and cost. Before you hire someone, make sure to check their license and insurance and when they present you with a contract, review everything carefully.
Maine does not have a licensing program for builders, but before hiring anyone, be sure to verify their insurance and review their contract carefully.
Construction, Step-by-Step
Keep in mind Often, people who are their own general contractors have a difficult time. Building an ADU is more like building an entire home than a renovation. If you’re working with a design/build team or have hired a general contractor, they’ll manage the project (including contract negotiation, payment schedules, quality checks, and working with local departments and staff and other agencies). While it may cost more up front, you might save a lot of money by reducing delays or change orders, and get your ADU rented sooner too.
Step 1
Hire Your Contractor
If you are not using a design/build firm, you will need to hire a contractor for the construction phase of your ADU. You will use drawings from your designer to get bids from contractors and make sure you are specific about what you want each bid to include (license details, insurance information, examples of past work, etc.). Your design team may be able to help you with this.
It’s a good idea to select between at least three bids, and it’s okay to ask contractors clarifying questions about their bid. Your designer may be able to help you compare the bids. It’s a good idea to reach out to references and to consider your personal interactions with the contractor – you’ll want to feel like you work well together and that they understand your goals.
Looking for a contractor? Check our Professionals Directory.
Step 2
Monitor Construction
Once you have building permits, the contractor you hire will lead the construction of your ADU. Be sure you have all funding in place before you start construction.
While your contractor will lead the construction process, you will have the following responsibilities:
- Keep in touch with your contractor and set up a schedule for checking in. It’s a good idea to schedule a weekly check-in to stay up to date on the progress and any changes to the schedule or budget.
- Regularly walk through the construction area to monitor the quality of the work and make sure the work is progressing the way you expect.
- Be prepared to make decisions about the details—light fixtures, appliances, and other materials—in a timely manner so your contractor can stay on schedule.
- Follow the contract you agreed to, including any changes as described specifically in a change order form.
- Although your contractor will usually arrange the required city or utility inspections, it is your responsibility as the property owner to make sure that the inspections are conducted as required.
Timelines for construction vary, but 6-12 months is fairly common. Modular construction can take 4-6 months for materials to be ordered and completed in a factory, and another 4-8 weeks for finishing.
Step 3
Get Inspections
During construction, your ADU will be inspected multiple times to ensure it is being built according to the permitted plans (typical inspections include foundations/footings, framing, electrical/plumbing, and exterior finishes).
Many Building Departments have online portals or direct phone numbers for scheduling inspections. Generally, it is your and your contractor’s responsibility to schedule all required inspections. For a list of inspections and how to schedule, contact your Building Department. After your final inspection is approved, you may be issued a certificate of occupancy.
Your ADU is ready for move-in!
Ready to ADU?
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