Eastham · Cape Cod

ADUs in Eastham

Gateway to the Outer Cape — and to a smarter way to stay in the home you love. An accessory dwelling unit lets Eastham homeowners add income, age in place, and downsize without leaving town.

Our Home Town

We're based right here in Eastham

Our office sits at 4250 State Highway in North Eastham, next to Ace Hardware — so Eastham isn't just a town we serve, it's where we work every day. Eastham anchors the entrance to the Outer Cape, where Route 6 narrows and the National Seashore begins. It's a town of year-round neighbors, summer visitors, and a housing market squeezed between the two. For longtime residents, an ADU offers a way to put existing land to work without giving up the address, the neighbors, or the life they've built here.

Why an ADU Fits Here

Eastham character, Eastham opportunity

What makes Eastham Eastham—and how a well-designed accessory dwelling unit fits naturally into it.

Cape Cod National Seashore

National Seashore Gateway

Eastham holds the Salt Pond Visitor Center and the gateway to the National Seashore. That protected setting keeps the town desirable for year-round and seasonal renters alike — and it means a well-designed ADU sits in a community where housing stays in demand and short supply.

Bay & Ocean

First Encounter & the Bay Side

From First Encounter Beach on the bay to the Atlantic-facing Seashore, Eastham's two coastlines define its character. A single-level cottage or garage conversion can give an aging owner a comfortable, low-maintenance home while the larger house becomes a year-round rental.

Local Landmarks

Nauset Light & Three Sisters

Eastham's iconic Nauset Light and the Three Sisters lighthouses speak to a town proud of its heritage. ADU design here respects that scale — modest, subordinate units that fit quietly behind or beside the primary home.

The Housing Reality

Year-Round Housing Pressure

Eastham works hard to keep year-round residents and essential workers housed. An ADU is one of the gentlest tools available: it adds a home without changing the neighborhood, using land and infrastructure that already exist.

The Rules, In Brief

Eastham ADUs at a glance

How the statewide ADU law applies in Eastham — and what still gets decided locally.

By-Right, Statewide

Since February 2025, the Massachusetts Affordable Homes Act allows a first ADU by right in single-family zoning — no special permit or owner-occupancy requirement for that first unit.

Size Limits

A by-right ADU is capped at 900 square feet or 50% of the primary dwelling's floor area, whichever is smaller. Larger or second units may require additional local review.

Septic & Title 5

Like most of the Outer Cape, Eastham relies on private septic. Title 5 capacity is often the single biggest design driver here — we assess it early so there are no surprises.

Local Bylaw Reconciliation

Eastham has been updating its local ADU bylaw to align with state law. Setbacks, height, and short-term-rental rules are still set at the town level, so current details matter.

Local Knowledge

What to think about for an Eastham ADU

Two factors shape most Eastham projects. The first is septic: many lots are served by Title 5 systems sized for the existing house, so adding bedrooms can trigger an upgrade. We evaluate your system's capacity at the very start, because it often determines whether a detached cottage, a garage conversion, or a within-the-footprint reconfiguration is the most cost-effective path. The second is the Seashore and resource overlays — properties near protected land or wetlands may carry extra setback or conservation review. None of this is a barrier; it's simply why an Eastham ADU benefits from local experience and an early, honest assessment.

Please verify current local rules. ADU requirements are evolving as Eastham reconciles its local bylaw with the Massachusetts Affordable Homes Act. The summaries here are general guidance, not legal advice. Always confirm setbacks, septic requirements, height, lot coverage, and short-term-rental rules with the Eastham building and planning departments before relying on them. We help our clients do exactly that as part of every project.

Across the Lower Cape

ADU guidance for every Lower Cape town

We serve all eight Lower Cape towns. Explore the others, or reach out about Eastham.

Let's Talk

Thinking about an ADU in Eastham?

The first conversation is free. Tell us about your Eastham property and what you're trying to solve—rental income, family space, or downsizing in place—and we'll walk you through whether it makes sense, with a preliminary design before any estimate.

Start with a Free Consultation

Vern Hatt · Licensed Construction Supervisor #CS62739 · Home Improvement Contractor #177590