ADU Rules in Pembroke, MA
Yes. Pembroke accepts ADUs by-right up to 900 sq ft. The friction is not zoning. It is septic capacity, the Great Sandy Bottom Pond and Silver Lake watershed overlays, Conservation Commission filings, and variable soils.
Call BuildX: (781) 627-7000
Pembroke accepts ADUs by-right
Planning Board vote: unanimous roll call · March 3, 2025On March 3, 2025, the Pembroke Planning Board voted unanimously by roll call to accept ADUs by-right, in compliance with state law [Planning Bd 3/3/25]. Mr. Taylor made the motion and Ms. Siciliano-Perry seconded. The Board noted on the record that the state cap is 900 sq ft, and that, in its words, a resident need only go to the building department to obtain a building permit. State law (760 CMR 71.00, effective February 2, 2025) preempts several restrictive provisions of Pembroke's older January 2024 bylaw for protected-use ADUs [760 CMR 71].
Can I build an ADU in Pembroke, MA?
Yes. Pembroke's Planning Board voted on March 3, 2025 to accept protected-use ADUs by-right in single-family residential zones, up to 900 sq ft, under building permit only. No special permit is required for a protected-use ADU that meets state criteria. Pembroke has no public sewer, so Title 5 septic capacity is the gating constraint.
What state law preempts in Pembroke
Pembroke's January 2024 zoning bylaw was written before the Affordable Homes Act. For a protected-use ADU (900 sq ft or less, attached or detached, on a single-family lot), state law (760 CMR 71.00) preempts five of the old bylaw's provisions [760 CMR 71] [Bylaw 2024]:
- Attached-only restriction: Preempted. State allows detached protected-use ADUs.
- Owner-occupancy requirement: Preempted. State prohibits owner-occupancy mandates for protected-use ADUs.
- 800 sq ft size cap: Preempted. State allows up to 900 sq ft.
- One-bedroom and two-occupant limit: Preempted. State sets no bedroom or occupant cap for protected-use ADUs.
- Special permit requirement: Preempted. State requires by-right approval for protected-use ADUs.
What Pembroke can still enforce: one ADU per residential lot, no commercial use except permitted home occupations, a building permit, Title 5 and Board of Health rules, and wetlands, floodplain, and watershed overlay regulations [760 CMR 71].
Show the bylaw history, the compliance vote, and the state preemption note
Pembroke adopted its ADU provisions in an earlier Town Meeting, reflected in the January 2024 published zoning bylaw [Bylaw 2024]. Those provisions were restrictive: attached-only, owner-occupied, capped at 800 sq ft, limited to one bedroom and two occupants, and gated by a special permit.
The Massachusetts Affordable Homes Act, implemented through 760 CMR 71.00 effective February 2, 2025, changed the floor. For protected-use ADUs, the state mandates by-right approval in zones that allow single-family dwellings, allows detached units, removes owner-occupancy mandates, and sets the cap at 900 sq ft or half the existing dwelling, whichever is less.
Then Pembroke went on the record. At the March 3, 2025 Planning Board meeting, the Board voted unanimously by roll call to accept ADUs by-right in compliance with state law [Planning Bd 3/3/25]. That is a clean public signal: the town is operating consistent with the new rule even where the published bylaw text has not yet been formally amended. The Board's documented language was direct: a resident need only go to the building department to obtain a building permit.
For most homeowners, the practical answer is straightforward. A Pembroke ADU at or under 900 sq ft, on a single-family lot, is a by-right project processed under a building permit. You do not need a special permit hearing. The older bylaw's attached-only, owner-occupancy, 800 sq ft, and one-bedroom limits are preempted for protected-use ADUs.
Two notes on confirmation. First, the town may file a formally amended ADU bylaw with the Attorney General's office; confirm the current bylaw status with the Building Department before design. Second, Pembroke's old bylaw also addresses parking, shared driveways, and entrance visibility to preserve single-family appearance; confirm which of those still apply to your protected-use ADU. Call the Pembroke Building and Inspectional Services office at (781) 293-3864.
Where Pembroke ADU projects actually slow down is downstream of zoning: Title 5 capacity, because Pembroke has no public sewer; Conservation Commission filings near the town's wetlands, rivers, and four named ponds; and the watershed overlays that protect drinking water for Pembroke and neighboring towns.
Garage conversion ADU
A common variation of either the detached or attached ADU paths, depending on the garage configuration. Pembroke's bylaw does not treat garage conversion as a separate ADU category; it is classified based on whether the converted structure is structurally attached to the principal dwelling.
- If the garage is attached to the house: Treated as an attached ADU
- If the garage is detached from the house: Treated as a detached ADU
- Best for: Properties with a structurally sound existing garage; ability to reuse foundation, walls, and roof; often faster than ground-up construction
- Watch for: Foundation adequacy, insulation upgrades, separate-entrance and bathroom plumbing, garage-door replacement with proper wall and window framing, and septic design flow because Pembroke is septic only
Pembroke ADU Rules at a Glance
The six things most homeowners ask first. Tap "View all rule details" for the complete data set.
View all Pembroke rule details
- ADU types allowed: Detached, attached, interior conversion (detached confirmed by state preemption)
- Planning Board compliance vote: Unanimous roll call, March 3, 2025 [Planning Bd 3/3/25]
- Named movers: Mr. Taylor moved, Ms. Siciliano-Perry seconded
- Max size: 900 sq ft or 50% of principal dwelling, whichever is less
- Old 800 sq ft cap: Preempted by 760 CMR 71.00
- Owner-occupancy: Old local clause preempted for protected-use ADUs
- Attached-only rule: Preempted; detached allowed
- ADUs per lot: One per residential lot (still enforceable)
- Sewer status: No public sewer; entirely private septic
- Aquifer overlay: Zone II wellhead protection for Pembroke's municipal wells
- Watershed overlays: Great Sandy Bottom Pond (source water for Abington/Rockland JWW) and Silver Lake (Brockton's supply)
- Flood zones: Riverine Zone A along the North and South Rivers; pond-adjacent areas
- Dimensional standards (lot, frontage, setbacks, height): Per the Pembroke zoning bylaw dimensional table. Confirm exact values with the Pembroke Planning Department.
- Permitting: Online (credit card online; cash or check in office) [Building Dept]
Why BuildX Knows Pembroke ADUs
Pembroke is BuildX home territory. We build here, and we know the septic, watershed, conservation, and soil constraints that drive a Pembroke ADU project more than the zoning does.
Pembroke Home Territory
Pembroke is BuildX home territory. We are your neighbors, not a regional contractor. We build here, so we know Pembroke ADU parcels, septic constraints, watershed overlays, and conservation filings firsthand.
See One in Person
Walk through a real, finished BuildX ADU before you sign anything. Private showings are available by appointment.
Day 1 Property Review
Before quoting, we check zoning, septic and Title 5, FEMA flood zone, wetlands, watershed overlays, and aquifer status.
BuildX in Pembroke
Pembroke is BuildX home territory. We are not a regional contractor visiting Pembroke, we are your neighbors. The list below carries each project's current status:
- McAdam/Swann (Completed): 515 GFA · 1-Bed, 1-Bath
- Kroon (Pre-Construction): 900 GFA · 2-Bed, 1-Bath
- Doran (Pre-Construction): 900 GFA · 1-Bed, 1-Bath
- Gransaull (Pre-Construction): 900 GFA · 1-Bed, 1.5-Bath
Real families. Real builds. Real ADUs on the South Shore. See more BuildX ADU builds →
What Can Complicate a Pembroke ADU?
In Pembroke, the bylaw is not usually what moves project cost and timeline. Your parcel's septic, watershed, conservation, and soil conditions are. The factors that come up most often:
Do I need septic approval for a Pembroke ADU? Septic
Likely affects you: Pembroke has no public sewer. Every residential lot in town is on private septic, so Title 5 applies to essentially every ADU project here.
Yes. Pembroke has no municipal sewer; the entire town is on private septic [Building Dept]. Adding an ADU bedroom adds wastewater design flow, so a Title 5 inspection and capacity check, plus a reserve area, are typically required through the Board of Health before the ADU permit is approved [Title 5].
Cost impact: $30,000 to $60,000 most likely for a Title 5 capacity check plus possible system upgrade when an older system cannot carry an additional ADU bedroom.
Pembroke participates in the WaterSmart South Shore SepticSmart program with the North and South Rivers Watershed Association. Because the whole town is septic, we pull Title 5 records and assess reserve-area capacity before any design work begins.
How do the Pembroke watershed overlays affect an ADU? Watershed
Likely affects you if: your parcel drains toward Great Sandy Bottom Pond or sits in the Silver Lake watershed. Pembroke sits in two multi-town drinking-water situations at once.
Pembroke has an unusual dual water-supply role. Great Sandy Bottom Pond, inside Pembroke, is the source water for the Abington and Rockland Joint Water Works (the Hingham Street Reservoir system). Properties in that watershed face heightened scrutiny on septic siting, runoff, and impervious surface [Abington/Rockland JWW]. We pull this overlay map first.
At the same time, parts of Pembroke drain into the Silver Lake watershed, which is Brockton's drinking-water supply and also serves Halifax. Strict septic, impervious-surface, and use restrictions apply where the Silver Lake overlay reaches into Pembroke [Silver Lake].
If your address falls in either watershed, expect additional engineering and review. Confirm your parcel's watershed status before design; we map it on the Day 1 property review.
Do wetlands, ponds, or conservation rules affect Pembroke ADUs? Conservation
Likely affects you if: your lot is near one of Pembroke's four named ponds, the North or South River, or any mapped wetland buffer.
Yes if your parcel falls within a wetland buffer or near a pond or river. Pembroke has four named ponds, Furnace Pond, Oldham Pond, Stetson Pond, and Great Sandy Bottom Pond, the densest set of named water features in our audit set so far [Wikipedia]. The North and South Rivers also run through town, which is why Pembroke partners with the North and South Rivers Watershed Association [NSRWA].
The Pembroke Conservation Commission administers wetlands review under MGL c.131 §40 (the state Wetlands Protection Act) [Wetlands Act] plus the town's local wetlands bylaw. Adding an ADU near a pond, river, or wetland resource area can trigger a Notice of Intent or Request for Determination filing.
Cost impact: +$5,000 to $15,000, plus roughly 6 to 10 weeks of additional review when a conservation filing is required.
How does the Pembroke aquifer overlay affect ADUs? Aquifer
Likely affects you if: your parcel falls within a Zone II wellhead protection area for Pembroke's municipal wells.
Pembroke has Zone II wellhead protection overlays around its own municipal wells, run by the Water Department at (781) 709-1425 [MassGIS]. Because the whole town is on septic, adding an ADU bedroom adds wastewater design flow, and Zone II overlays affect how septic systems can be sited and sized near wellheads.
Pembroke also shares parts of the Plymouth-Carver aquifer system through the Silver Lake watershed that extends in from Kingston. A MassGIS overlay check on Day 1 tells you whether your parcel sits within Zone II. We pull this before quoting.
What flood-zone rules affect Pembroke ADUs? Flood
Likely affects you if: your parcel is along the North or South River corridor or adjacent to one of the four named ponds.
Pembroke is inland, not on the ocean, so it does not have coastal flood exposure. It does have riverine flood zones. FEMA maps Zone A along the North and South River corridors, plus pond-adjacent flood areas around Furnace, Oldham, Stetson, and Great Sandy Bottom Ponds [FEMA].
An ADU on a riverine or pond-adjacent parcel can require elevation, flood-resistant materials, and engineer-stamped flood compliance. Confirm your parcel's FEMA zone before design; we run the FEMA lookup on Day 1.
Why do Pembroke soils and water tables matter for an ADU? Soils
Likely affects you if: your lot sits on lower or wetter ground, which is common across parts of Pembroke.
Per Block Renovation's Pembroke and Hanover Home Additions Guide (December 2025), Pembroke sits on terrain with variable soil quality and occasional high water tables [Block Reno guide]. That matters for both the septic design and the ADU foundation.
A professional site evaluation before design can identify drainage or foundation concerns early. Proper grading, gutters, and basement waterproofing are not optional on the wetter Pembroke lots. We factor a site evaluation into the Day 1 review on parcels where the soils are a question.
Does Pembroke have a transit parking exemption? Transit
Likely affects you if: you were counting on a transit-adjacent parking break. Pembroke does not have a commuter rail station in town.
Pembroke does not have an MBTA commuter rail station within town limits. The closest station is Hanson Station on the Old Colony Line, in neighboring Hanson [MBTA Hanson]. Because there is no in-town station, the state's transit-adjacent parking exemption does not apply to Pembroke parcels in the way it applies in towns with their own station.
Pembroke's local rules address parking and shared driveways. Confirm Pembroke's current MBTA Communities Act status and any parking requirements with the Building Department, since proximity to Hanson Station can carry zoning obligations.
What Does a Pembroke ADU Cost?
A Pembroke ADU should not be priced from square footage alone. Two similar ADUs can price very differently depending on septic capacity, watershed overlays, conservation review, soil conditions, and site access.
That is the full span of our 14 floor plans. Prices include the complete building package, foundation through move-in-ready finishes. Site work is priced separately after a lot evaluation.
Pembroke-specific cost premium factors
See full ADU pricing and floor plans. For a Pembroke-specific quote, call (781) 627-7000. We will not quote a Pembroke ADU until we know your septic and reserve-area capacity, watershed status, and conservation triggers.
How the Pembroke ADU Permit Process Works
For a protected-use ADU, Pembroke processes the project under a building permit, by-right, per the March 3, 2025 Planning Board vote.
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1
Parcel review
1 to 2 weeks
BuildX maps your parcel against zoning, septic and Title 5 capacity, FEMA flood zone, wetlands, watershed overlays, and aquifer status before quoting. On a septic-only town like Pembroke, this step usually determines whether the rest of the timeline is straightforward or extended. MassGIS and watershed overlay checks happen on Day 1.
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2
Board of Health and Title 5
Varies by system age and reserve-area capacity
Because the town is entirely septic, the Board of Health Title 5 review and reserve-area documentation is gating. Adding an ADU bedroom adds design flow, so the existing system must be confirmed adequate or upgraded before the ADU is approved.
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3
Building permit
Confirm current turnaround with the Building Department
For a protected-use ADU, Pembroke processes the project under a building permit, by-right, per the March 3, 2025 Planning Board vote [Planning Bd 3/3/25] [760 CMR 71]. Pembroke offers online permitting (credit card online; cash or check in office) [Building Dept].
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4
Overlay reviews (if triggered)
Add several weeks when triggered
Conservation Commission filing for wetland, pond, or riverfront buffers (MGL c.131 §40 plus the local bylaw), watershed-overlay engineering for Great Sandy Bottom Pond or Silver Lake parcels, and FEMA flood compliance for riverine or pond-adjacent parcels. These can extend the critical path.
Planning assumption: on a clean septic parcel with no overlay triggers, the path is short because the ADU is by-right. The variable that moves the timeline most in Pembroke is the Title 5 and reserve-area review, plus any conservation or watershed filing.
Inspections in Pembroke must be called in to the office, not directly to the inspector, and are scheduled for the next day. Plan accordingly. Confirm current administrative posture at (781) 293-3864.
What Pembroke Zoning Districts Allow ADUs?
Pembroke uses a traditional use-separation zoning structure, not a form-based code. The town is predominantly residential, with a smaller share of business and commercial zoning. For protected-use ADUs, the Planning Board's March 3, 2025 vote established by-right acceptance in single-family residential zones. The dimensional standards below come from the Pembroke zoning bylaw dimensional table; confirm the exact figures for your district with the Planning Department.
Single-family residential zones Where most Pembroke ADUs go
- ADU allowance: Protected-use ADUs accepted by-right per the March 3, 2025 Planning Board vote
- Max size: 900 sq ft or 50% of the principal dwelling, whichever is less
- Min lot, frontage, setbacks, coverage, height: Per the Pembroke zoning bylaw dimensional table. Confirm exact values with the Pembroke Planning Department.
ADU rules: Detached, attached, and interior-conversion ADUs are allowed for protected-use projects up to 900 sq ft, processed under building permit only. The old bylaw's attached-only, owner-occupancy, 800 sq ft, and one-bedroom limits are preempted for protected-use ADUs [760 CMR 71].
What this means for your ADU: On a septic-only town, your usable building area is driven less by the dimensional table and more by where the septic system and its reserve area can go. We map setbacks and septic together so the ADU placement works on the first pass.
Variant residential sub-districts
Pembroke's older bylaw text names specific residential districts. State law (760 CMR 71.00) protects by-right ADUs in zones that allow single-family dwellings. If your parcel is in a residential sub-district and you are unsure whether the protected-use path applies, do not rely on an outside reading of state law. Confirm with the Pembroke Planning Department how the town is applying 760 CMR 71.00 to your specific district.
The Planning Board can also grant special permits to modify building or lot coverage limits where there is no negative effect on neighbors or residential character [Bylaw 2024]. That is a separate, optional path from the by-right protected-use route.
Overlay districts. Aquifer, watershed, wetlands, floodplain.
Zone II wellhead protection for Pembroke's municipal wells, the Great Sandy Bottom Pond and Silver Lake watershed overlays, local wetlands jurisdiction near the four named ponds and the North and South Rivers, and FEMA riverine flood areas. Overlays modify, but do not prevent, ADU construction.
Overlay analysis happens on Day 1 with MassGIS layers. We pull your parcel's overlays before quoting.
Source: Town of Pembroke Zoning Bylaws (January 2024). ADU provisions partially preempted by 760 CMR 71.00; Planning Board accepted ADUs by-right March 3, 2025.
Sewer or Septic? Pembroke Is Septic, Town-Wide.
This is the single biggest cost variable in any Pembroke ADU project. Pembroke has no municipal sewer. Every residential lot in town is on private septic, which means Title 5 and a reserve area apply to essentially every ADU here.
Show Title 5, water utility, and watershed details
- Water Utility: Pembroke Water Department, (781) 709-1425, with Zone II wellhead protection overlays
- Septic upgrade cost: $30,000 to $60,000 most likely
- Title 5 trigger: Adding a bedroom adds design flow, so a Title 5 inspection plus reserve area is required [Title 5]
- Septic program: WaterSmart South Shore SepticSmart, with the North and South Rivers Watershed Association
- Watershed overlays: Great Sandy Bottom Pond (Abington/Rockland JWW source water) and Silver Lake (Brockton's supply)
Pembroke is septic, town-wide. We do not quote a Pembroke ADU until we know your existing system's capacity and whether your parcel sits in a protected watershed. A Title 5 inspection answers the capacity question for your specific property.
Pembroke Organizes Around Its Ponds
Pembroke's distinct areas organize around the town center and its four named ponds. Each has its own conservation, flood, and watershed profile. A pond-adjacent ADU is a different project from a town-center ADU.
Pembroke Center Mixed
The denser town-center area. Less septic complexity than the outlying pond areas in some cases, but still septic, and may carry more architectural scrutiny given the town's Colonial and Cape character.
Septic: Required, town-wide.
Furnace Pond area Conservation
Pond-adjacent. Conservation Commission buffer filings are common, and architectural sensitivity matters near the water.
Septic: Required. Flood: Pond-adjacent FEMA areas possible.
Oldham Pond area Conservation Flood
Pond-adjacent, with conservation buffers and FEMA flood considerations along the pond edge.
Septic: Required. Flood: Pond-adjacent FEMA areas possible.
Stetson Pond area Conservation
Pond-adjacent. Conservation Commission buffer filings are common for projects near the water.
Septic: Required.
Great Sandy Bottom Pond watershed Watershed
This pond is the source water for the Abington and Rockland Joint Water Works. Properties in the watershed face heightened scrutiny on septic siting, runoff, and impervious surface. This is a multi-town water-supply consideration unique to Pembroke [Abington/Rockland JWW].
Septic: Required, with extra review. Watershed: Heightened scrutiny.
What Pembroke's Planning Board Says
When a town's Planning Board votes unanimously, on the record, to accept ADUs by-right, the path is by-right.
Now all a resident need to do is go to the building department to obtain a building permit.
That is the operating posture documented by the Town of Pembroke. The Board voted unanimously by roll call, with Mr. Taylor moving and Ms. Siciliano-Perry seconding, to accept protected-use ADUs by-right in compliance with state law. For a protected-use ADU at or under 900 sq ft, you go to the Building Department for a building permit. The town may also file a formally amended ADU bylaw with the Attorney General's office; confirm the current bylaw status before design.
Pembroke Building Department
Pembroke Building and Inspectional Services
- AddressPembroke Town Hall, 100 Center Street, Room 3, Pembroke, MA 02359
- Phone(781) 293-3864
- Local Building InspectorJoseph Stack [Building Dept]
- Administrative AssistantJenn Condon [Building Dept]
- Inspection schedulingCall inspections in to the office, not directly to the inspector. Inspections are scheduled for the next day.
- Online permittingCredit card payment online; cash or check in office.
- Building Departmentpembroke-ma.gov/building-inspectional-services
- Water Department(781) 709-1425 (Zone II well overlays)
Pembroke runs a small, accessible department. One number, (781) 293-3864, handles permits and inspections. Note that the Building Department refers zoning and planning questions to the Planning Department, so coordinate between the two when your project touches a district or overlay question.
Questions to ask when you call Pembroke
- How is Pembroke processing protected-use ADUs after the March 3, 2025 Planning Board vote?
- Are detached protected-use ADUs being approved by-right under a building permit?
- Do I need a zoning permit before submitting the building permit?
- What Title 5 and reserve-area documentation does the Board of Health require?
- Is my parcel in the Great Sandy Bottom Pond or Silver Lake watershed?
- Does my parcel need a Conservation Commission filing for a wetland, pond, or river buffer?
- Has Pembroke filed an amended ADU bylaw with the Attorney General's office since the March 2025 vote?
Explore Pembroke ADU Topics
Jump to deep-dive sections on this page.
Pembroke ADU FAQs
Can I build a detached ADU in Pembroke?
Yes, despite the old bylaw saying attached only. The Pembroke Planning Board voted unanimously by roll call on March 3, 2025 to accept ADUs by-right in compliance with state law. State law (760 CMR 71.00) preempts the old attached-only restriction for protected-use ADUs, so a detached ADU up to 900 sq ft is allowed under a building permit. Confirm the current administrative posture with the Building Department at (781) 293-3864.
Do I need a special permit for a Pembroke ADU?
No, not for a protected-use ADU. The Planning Board's March 3, 2025 vote established that a protected-use ADU (900 sq ft or less, on a single-family lot) is processed by-right under a building permit. The old bylaw's special-permit requirement is preempted by 760 CMR 71.00 for protected-use ADUs.
Do I need to live there?
State law (760 CMR 71.00, effective February 2, 2025) preempts owner-occupancy requirements for protected-use ADUs, so Pembroke's older owner-occupancy clause is not enforceable for a protected-use ADU. Confirm the current operating posture with the Building Department before signing a lease.
How big can a Pembroke ADU be?
Up to 900 square feet, or 50% of the principal home's gross floor area, whichever is less. Pembroke's older 800 sq ft cap is preempted by 760 CMR 71.00 for protected-use ADUs, so the state cap of 900 sq ft applies.
Can I have two bedrooms?
State law preempts Pembroke's older one-bedroom and two-occupant limit for protected-use ADUs. Per Block Renovation's Pembroke and Hanover Home Additions Guide (December 2025), ADUs may have up to two bedrooms, consistent with that preemption [Block Reno guide]. Confirm your specific design with the Building Department.
Will I need a septic upgrade?
Likely. Pembroke has no public sewer, so every lot is on private septic. Adding an ADU bedroom adds wastewater design flow, which triggers a Title 5 inspection and reserve-area review through the Board of Health [Title 5]. If your existing system lacks capacity, an upgrade adds $30,000 to $60,000 most likely. The first thing BuildX does on a Pembroke property is assess septic capacity before any design work.
What does a Pembroke ADU cost?
BuildX ADU pricing ranges from $284,301 to $525,861. That covers the complete building package, foundation through move-in-ready finishes; site work is priced separately after a lot evaluation. Pembroke-specific drivers move a project within that band: a septic upgrade adds $30,000 to $60,000 most likely; a Conservation Commission filing adds $5,000 to $15,000 plus several weeks; and Great Sandy Bottom Pond or Silver Lake watershed parcels add engineering and review. For a property-specific quote, call (781) 627-7000.
Who do I call about building an ADU in Pembroke?
For official town process questions (permits, fees, inspection scheduling, building code interpretation), call Pembroke Building and Inspectional Services at (781) 293-3864. Zoning and planning questions are referred to the Planning Department.
For parcel-level feasibility, septic and watershed assessment, cost estimates, design options, and construction planning, call BuildX at (781) 627-7000.
The two are different conversations. The town can tell you what is administratively required. BuildX can tell you what is realistic on your specific parcel and what it will actually cost to build.
Can I build an ADU on septic in Pembroke?
That is the only way to build one here, because Pembroke has no public sewer. The existing septic system must have capacity under Title 5 (310 CMR 15.000) to handle the additional bedroom an ADU typically adds, and a reserve area is required by the Board of Health.
If your existing system lacks capacity, an upgrade or full replacement adds $30,000 to $60,000 most likely. On wetter parcels with variable soils, a professional site evaluation is needed before design to identify drainage and foundation concerns early.
The first thing BuildX does on a Pembroke property is pull the Title 5 records and assess capacity and reserve area before any design work begins. This is part of the Property Review.
Sources Reviewed
Last verified: September 12, 2026. Grouped by source type so you can see which claims come from town law, state law, town process, local constraints, and media records.
View all 23 sources, grouped
- Town of Pembroke. Planning Board Meeting Minutes, March 3, 2025. Unanimous roll-call vote to accept ADUs by-right in compliance with state law. Mr. Taylor moved; Ms. Siciliano-Perry seconded. Board noted the 900 sq ft state cap and that a resident need only obtain a building permit.
- Town of Pembroke. Town of Pembroke Zoning Bylaws (January 2024). Pre-state-law ADU provisions, partially preempted by 760 CMR 71.00 after February 2, 2025.
- Commonwealth of Massachusetts. Accessory Dwelling Units (760 CMR 71.00). Effective February 2, 2025. Preempts Pembroke's attached-only, owner-occupancy, 800 sq ft, one-bedroom, and special-permit provisions for protected-use ADUs.
- MassDEP. Title 5 (310 CMR 15.000) Compliance for ADUs FAQ. Highly relevant; Pembroke is entirely septic.
- Massachusetts General Laws. M.G.L. Chapter 40A, Section 3. As amended by the Affordable Homes Act (Chapter 150 of the Acts of 2024). ADU provisions.
- Massachusetts General Laws. M.G.L. Chapter 131, Section 40. Wetlands Protection Act.
- Town of Pembroke. Building and Inspectional Services. Local Building Inspector Joseph Stack; Administrative Assistant Jenn Condon; Building Department staff Pete DelPrete; (781) 293-3864; Town Hall, 100 Center Street, Room 3. Inspection scheduling and online permitting.
- Town of Pembroke. Building / Inspectional Services landing page. Alternate department landing.
- Town of Pembroke Conservation Commission. Conservation Commission filings for wetlands, ponds, and riverfront buffers (department contact via Pembroke Town Hall).
- Town of Pembroke Highway Department. (781) 293-5620. Department contact for road and access questions.
- Live Pembroke. Town and Government directory. Community-resource town directory.
- MBTA. Old Colony Line, Hanson Station. Closest commuter rail station to Pembroke.
- Wikipedia and U.S. Census 2020. Pembroke, Massachusetts. Multi-pond geography, North and South Rivers, population, and architectural character (cited cautiously).
- Census Reporter. Pembroke Town Profile. Demographics (population approximately 18,500).
- Plymouth County Registry of Deeds. Plymouth County Registry of Deeds. Deed registry for Pembroke (Plymouth County).
- MBTA. Greenbush Line. Alternate commuter rail context.
- MassGIS. Aquifer and Zone II Wellhead Protection GIS layers. Zone II recharge zones for Pembroke's municipal wells.
- Federal Emergency Management Agency. National Flood Hazard Layer, Flood Map Service Center. Pembroke riverine and pond-adjacent flood zones.
- North and South Rivers Watershed Association. Watershed protection partnership covering Pembroke's North and South Rivers.
- City of Brockton Water Department and MassDEP. Silver Lake watershed (Brockton's drinking-water supply; also serves Halifax and reaches Pembroke).
- Abington and Rockland Joint Water Works. Source Water Assessment Program (SWAP) report. Hingham Street Reservoir system; Great Sandy Bottom Pond in Pembroke is source water.
- Block Renovation. Pembroke and Hanover Home Additions Guide. December 2025. Third-party renovation guide with editorial review documenting Pembroke ADU rules after the March 2025 vote (cited cautiously).
- BackyardADUs. Pembroke ADU rules summary. Third-party aggregator (cited cautiously).
Nearby South Shore ADU Rules
Pembroke borders Hanover to the north, Hanson to the west, Marshfield to the east, and Halifax and Kingston to the south, sharing the Silver Lake watershed with Halifax and Kingston. All are home territory for BuildX, the same neighborhoods we build in.
ADU Rules by City in the BuildX Service Area
BuildX serves 40 towns across four areas of southeastern Massachusetts. Each city has its own ADU bylaw, sewer or septic split, overlay map, and Building Department contact. Jump to the rules for your town:
South Shore (22)
South Coast (9)
Bridgewater Area (5)
Thinking about an ADU in Pembroke?
BuildX can review your Pembroke parcel for zoning, septic and Title 5 capacity, FEMA flood zone, wetlands, watershed overlays, and aquifer status before you spend money on design or permitting. Pembroke is BuildX home territory, so we know the constraints that drive your project and the by-right path the Planning Board confirmed in March 2025.
See our ADU project portfolio or visit the ADU Home TourDisclaimer: The information on this page is drawn from live interviews, podcast episodes, municipal bylaws, planning board materials, town websites, and other publicly available sources, and reflects what was accurate as of the original recording or verification date. Pricing, timelines, materials, regulations, zoning rules, permit processes, fees, and overlay district boundaries can change -- sometimes without public notice -- and no two towns interpret or apply the rules the same way. This page is for informational purposes only and should not be relied upon as the basis for any purchasing, construction, or investment decision. BuildX makes no guarantee that the information is current or complete for your specific parcel. Before making any decisions, contact the town directly or call BuildX at (781) 627-7000 or schedule a Project Clarity Call to review your specific situation.