Permitting
Overview
- Understand what’s required in your permit application
- Know what to expect from application review
- Get started on your application
- Understand the types of fees you may need to pay
The permitting process can be straight-forward if you are prepared and understand what to expect. You should have an idea of how the process works from your conversations with planning staff, and your designer should be familiar as well. Permitting starts with an application package and ends with a building permit, which allows you to start construction.
Project Timeline
The Permitting phase typically takes 1-6 months. Most ADU projects take 12-18 months to complete, but some extend to 24 months or more.
FAQs
Do I need permits from utility companies?
When building an ADU, utilities such as water, sewer, and electricity are an important part of the permitting and construction process. Municipalities may require separate or shared connections to water and sewer, but they cannot make ADU utility requirements more burdensome than what is typically required for a new home or other accessory structure. Water districts in Maine commonly require separate meters and connections.
If public sewer/water is not available, proof of capacity for on-site septic and well systems may be required by the local plumbing inspector or code officer. Fees must be proportionate and not excessive compared to other similar structures.
While local ordinances vary, ADUs can usually share an electric meter with the primary residence or apply for a separate service/meter through the utility provider. It depends on usage needs and rental plans.
Some municipalities (e.g., Portland) may require a drainage or stormwater review, especially for detached ADUs that increase impervious surface.
How much does it cost to get permits for an ADU?
ADUs can be charged a variety of fees from your local government, the State, and other agencies. Some fees are based on details of the project while others are fixed. The total amount depends highly on your property and plans.
Typically, ADUs in Maine can expect to incur the following fees:
- Planning review: $100–$300
- Building permit: $10–$15 per $1,000 of project cost
- Impact fees: Vary by town; often waived for ADUs under 750 sq ft
- Utility hook-up or connection fees
What permits are required for ADUs?
Submitting an application is different in each community. Some have online portals while others ask for multiple sets of paper copies on various sizes of paper. Some locations require one application package, while otherwise require separate processes from the Planning and Building departments. Check with local Planning staff to confirm the application process and requirements and for details about permit materials.
What if I have an unpermitted ADU on my property already?
An unpermitted ADU can make it difficult to sell or refinance your property. If the ADU is being built, the City or County can stop construction and increase permitting and inspection fees. Existing unpermitted ADUs can go through the permitting process, and local staff will work with you to determine what would be involved to bring your ADU up to code.
If you already have an ADU on your property that was built without permits, you may be wondering how Maine’s new housing law (LD 2003) affects your situation. Here’s what you need to know:
Under LD 2003, the Unpermitted Units aren’t “Grandfather”, therefore LD 2003 does not automatically legalize unpermitted ADUs. Homeowners with existing, unpermitted units must still go through the local permitting process to bring their ADU into compliance. You may be able to retroactively permit the unit if it meets current zoning, building, life safety, and utility requirements.
What You Can Do If You Have an Unpermitted ADU:
- Contact your local Code Enforcement Officer or Planning Department
- Ask what the process is to legalize an existing ADU.
- They may require inspections, as-built drawings, or upgrades to meet current code.
- Prepare for inspections and possible upgrades
- You may need to upgrade electrical, plumbing, egress, or fire safety components.
- In some cases, structural work may be needed if the unit doesn’t meet building code.
- Check zoning compliance
- LD 2003 may make it easier to legalize your unit if it now meets the new standards (e.g., no lot size minimums, reduced parking, etc.).
- However, if the unit violates setback, size, or health/safety rules, it may not be permitted even under LD 2003
Be Aware of Possible Penalties
- Some municipalities may charge double permit fees or issue notices of violation if an unpermitted unit is discovered.
- However, many towns are willing to work with property owners to bring units into compliance—especially in support of affordable housing goals.
Permitting, Step-by-Step
Before you begin It’s helpful to meet with Planning staff before submitting your application. While not required, meeting with your designer and local staff before you submit your application might save time later in the process.
Step 1
Prepare Your Application Package
Once your ADU plans are finalized, you and your designer or contractor will submit your application package for approval. Your team will lead the process to prepare an application package.
Application requirements vary by where you live, but applications typically include:
- Site plan
- Architectural and structural drawings
- Building permit application
- Septic system confirmation (if applicable)
Some local Planning Departments have an ADU permit application or submittal requirements checklist that outlines all the required documentation and materials that must be submitted. Contact local staff to learn about your specific application process and requirements.
Step 2
Submit Your Application
Submitting an application is different depending on where you live. In most Maine municipalities, applications can be submitted online or in person at the Code Enforcement Office. Contact your local planning department or code enforcement for a checklist or guidance before applying.
After your application is submitted, the first step will be for your local Planning Department to review it for completeness. They will confirm your application is complete (meaning you correctly submitted all required materials and details) and then other departments and agencies will begin their review.
If you are building a conversion ADU or any ADU within an existing structure, local inspectors may be required to conduct a walkthrough of the intended space as a part of the application process. You will be notified by local staff if you need to schedule this inspection.
Step 3
Revise Your Application
Local staff will complete their review and provide any comments, typically within 10-20 days. If modifications are required, your team will revise and resubmit the application. It is typical to resubmit your plans at least once to clarify details and answer questions.
Most likely, this review will happen at a staff level (no hearings), but in less common instances, an additional permit or public hearing may be required.
If modifications to your plan are required, your team will revise and resubmit the application. Many local Planning Departments allow you to check your permit status online.
Step 4
Receive Permits
After your application is approved, staff will let you know that your permit is ready and how you can receive it. Once you have paid any remaining fees and you have your permit, you can begin construction. Often permits must be displayed at the site.
The duration of a building permit is generally determined by the local municipality, though many follow standards informed by the Maine Uniform Building and Energy Code (MUBEC). Typically, building permits are valid for six to 12 months from the date they are issued. Most municipalities require that construction begins within six months of issuance to keep the permit active. Once work has started, the permit often remains valid for up to 24 months, depending on local rules. If more time is needed, property owners can usually request a single extension, commonly for six months, as long as the request is made before the permit expires. For example, in the City of Portland, a building permit is valid for six months; if work begins within that period, the permit remains active for up to two years. To avoid delays or lapses, it’s always best to confirm specific timeframes and requirements with your local code enforcement office.
Ready to ADU?
Navigate project phases using this section on each page.
Support for permitting your ADU
Check out these resources for help.
ADU Professionals Directory
