Portland's published detached-ADU example totals $36,720.91, stacking land-use review, plan review, trade permits, surcharges, and inspections, per the City of Portland ADU guidance. That is a West Coast schedule, not a Greater Boston invoice.

The building-permit line still hides the rest of the bill. Water and sewer connection charges, plus school, traffic, or park impact fees, are separate items. Write each one down before you compare bids. Two similar permit totals can diverge once those lines are filled in.

Aureli Construction builds ADUs in Arlington, Belmont, Cambridge, Lexington, Medford, Somerville, Stoneham, Wakefield, Reading, and Melrose.

Table of Contents

• ADU Permit Fee Categories in Greater Boston
• What Massachusetts Law Says About ADU Fees
• Zoning Relief Fees in Cambridge MA
• How Fees and Permit Timing Shape Your Budget
• Recovering Design and Permit Costs Through Boston Assistance
• Questions Homeowners Ask and a Written Fee Worksheet

ADU Permit Fee Categories in Greater Boston

A headline building-permit number hides the rest of the ADU bill. Zoning review, trade permits, a water or sewer connection, and any impact charge are separate lines. I want each of those lines written down before I compare bids, because two proposals can share a construction price and still carry different permit costs.

Use the table as a planning sheet for a typical detached or attached ADU. Town schedules set the final dollars. The last column shows how each charge usually behaves.

The building permit moves with project valuation. Utility and impact charges move with a different question: is the unit newly created, and does it need its own connection? A tight lot may also need soil testing before the utility plan is real enough to price.

Keep construction cost off this stack. A worksheet to estimate ADU construction costs stays on its own line so the permit charges remain visible.

Practical rule: I do not treat the building-permit invoice as the permit bill. Add zoning, each trade permit, any connection charge, and any impact line before two bids sit side by side.

Aureli Construction handles the permitting from the required documents through the final application. The package includes permit forms, contractor insurance, construction drawings, and engineered plans. Permit expediting submits those drawings, follows up with inspectors, and manages revisions until approval.

What Massachusetts Law Says About ADU Fees

A low permit fee does not mean a low total. In Belmont, a charge labeled an impact fee may not be lawful as written.

Massachusetts Protected-Use ADU rules took effect on February 2, 2025. The Massachusetts ADU FAQs say towns may impose only reasonable fees under a reasonableness test. Covered charges include the building permit, site-plan review, and water, sewer, and utility-connection fees. Impact studies, reports, mitigation, and utility-connection requirements can't be charged to an ADU unless they're imposed on comparable single-family homes in the same zoning district. Our guide to Massachusetts ADU laws is the place to start that comparison.

Audit the notice in three steps.

1. List every line on the fee notice.
2. Compare each line with what the primary home would pay.
3. Note attached or detached, then separate sewer or water capacity charges from impact fees.

No impact fee doesn't mean no utility-related fee. Ask the building department, in writing, which lines are impact fees, which are permit or utility charges, and what basis supports each one.

Zoning Relief Fees in Cambridge MA

Cambridge publishes a zoning fee of $300 plus $200 for each dwelling unit requested when a property is converted to additional dwelling units, and the Cambridge zoning fee schedule bases that charge on the magnitude of relief requested, not on the relief finally granted. Trimming the request later may not lower the first charge.

Say the application asks for two units. That's $300 plus two times $200, or $700 in zoning fees before the building permit is issued. Cambridge's Inspectional Services Department manages the schedule. The invoice arrives after approvals from other departments are complete. Paying that invoice online by credit card or electronic check adds a service fee, so we keep the surcharge on its own line.

Setbacks, height limits, and lot coverage often decide whether relief is needed at all. We take those issues to the building department and, when needed, apply for a zoning variance, including the forms, fees, and public hearings. Before the design is final, ask whether the planned unit count and footprint need relief.

How Fees and Permit Timing Shape Your Budget

The permit bill is several charges, not one number. Design invoices, the ISD fee, a zoning appeal fee, trade permits, and utility connection or impact charges are separate lines due at different times. I would audit each line before comparing bids.

Boston's review order is what sets when each fee is paid.

1. Drawings and engineering come first. Architect, surveyor, and engineer invoices are paid before any permit is filed.
2. ISD reviews the drawings against Boston's Zoning Code. A substantial attached or detached ADU needs a long-form building permit, and ISD sets the fee by permit type and scope, not a flat ADU price, per Boston's ADU permitting page. Plans must also meet 780 CMR, the Massachusetts State Building Code.
3. If the plans don't comply, relief goes to the Zoning Board of Appeal. The city sets both the appeal deadline and the filing fee. That appeal fee and the building-permit fee stay on separate lines.
4. After the permit, trade permits and construction start. Rough inspections cover framing, electrical, and plumbing, then a final inspection comes before occupancy.

Permits for additions and ADUs can take several weeks. The timeline follows the town's workload, project size, and any zoning issues, so the schedule should be a written range rather than one date. The ADU permit process package includes permit forms, contractor insurance, construction drawings, and engineered plans, and those items are due before framing. Budget them in the months before construction. For a clear split between those soft costs and the build, start with understanding hidden project expenses with LendingXpress. Add a contingency for utility connection and impact charges that can change after plan review.

Recovering Design and Permit Costs Through Boston Assistance

Eligible Boston homeowners may seek reimbursement of design and permitting expenses up to a combined maximum of $7,500, according to Boston's ADU questions page. The program is limited to Boston projects. Cambridge, Somerville, and other towns should not budget around that cap.

The ceiling is one pool. Covered items are a general-contractor deposit or retainer, architecture, land surveying, engineering, building-permit fees paid to the Inspectional Services Department, and Zoning Board of Appeal fees.

Say the architect bill is $6,000, the building permit is $1,500, and surveying plus engineering is $1,200. That stack is $8,700. Reimbursement stops at $7,500, so $1,200 of those named costs stays with you. I would not read the cap as $7,500 for permits plus a separate design check.

Audit each line before you compare bids. A single building-permit number hides charges this list does not name. Utility connection charges and impact charges sit outside architecture, survey, engineering, ISD permit fees, and ZBA fees, so they remain yours even when the reimbursable stack already hits the cap. Price those lines on their own, then see how much of the named stack can come back.

Keep signed contracts, deposit receipts, dated invoices, permit receipts, and ZBA filing receipts in one folder so each reimbursable line matches a payment. Confirm eligibility with the city before you sign a design contract.

Questions Homeowners Ask and a Written Fee Worksheet

Will a waiver or reimbursement lower what I pay upfront? Usually not. Reimbursement follows payment, so budget the full amount and keep every receipt.

Can a fee estimate change after plan review? Yes. Valuation-based fees can be recalculated, and the utility configuration can change. Ask for a worksheet updated after review.

Does a bigger ADU always cost more in fees? The building permit rises with valuation, and some charges change at size thresholds. Check the schedule at each size you're considering before the design is final.

Then write the worksheet.

1. Request the current ADU fee schedule and list zoning, building, electrical, plumbing, gas, plan review, utility, and impact lines.
2. Confirm attached or detached, and whether any size threshold changes a category.
3. Ask if a new water or sewer connection is required, or whether the unit converts existing space.
4. Ask whether valuation-based fees are recalculated after plan review.
5. Confirm which reimbursement or waiver programs apply, and which documents they require.

A worksheet with those lines lets you compare contractor bids on the same basis. We offer a free on-site consultation and estimate, then handle permitting from the required documents through the final application. Our permit expediting submits the architectural drawings, follows up with inspectors, and manages revisions until approval, including in Medford, Lexington, Belmont, Somerville, and Cambridge.

Ready to get started? Contact Aureli Construction for a free estimate at homeadditionma.com.

We prepare the permit package, separate each fee line, and coordinate with Greater Boston building departments so the bill is clear before construction starts. If you're comparing ADU permit fees on a Cambridge, Boston, or nearby lot, bring the town's fee notice to a free on-site estimate. Visit Aureli Construction and we'll walk the charges with you.