Custom modular ADU built by Biviano Modular Builders in Plymouth County, MA
Accessory Dwelling Units · Up to 900 sq ft

Custom Modular
ADUs
Built in 8–12 Weeks.

In-law suites. Rental cottages. Home offices. Guest houses. Built to the same exacting standard as our full custom modular homes — at the same $250 per square foot, in the same 8–12 week timeline. Mike handles permits, design, build, and the entire town approval process.

900
Sq Ft Max
MA ADU Cap
$250
Per Square Foot
Same as Full Build
8-12
Weeks to
Move-In
4th
Generation
Contractor
MA
Licensed · Bonded
Insured
Same Quality. Smaller Footprint.

A Full Home
In 900 Sq Ft.

A modular ADU is not a shed with plumbing. It's a fully-engineered, code-compliant dwelling — same 2x6 framing, same Anderson 400 windows, same factory precision, same 8–12 week timeline as our full custom modular homes. Just compressed into 400–900 square feet of intentional design.

Massachusetts' 2024 statewide ADU reform made it dramatically easier for Plymouth County homeowners to add a second dwelling on their property — by-right in most cases, with a 900 sq ft cap. For families looking to bring aging parents home, generate rental income, or carve out a serious home office without leaving the property, modular ADUs are the fastest, most predictable way to add livable square footage.

Pricing parity is the headline. A 600 sq ft ADU is approximately $150,000. A 900 sq ft ADU is approximately $225,000. That includes Mike handling design, permits, septic capacity, foundation, crane set, finish work, and final inspection. No surprises. Locked in writing before the first shovel.

8-12
Weeks to Move-In
$250
Per Sq Ft
900
Sq Ft Max
2024
MA ADU Reform
Why ADUs with Mike
  • Same factory-built quality as full modular homes — no compromises
  • Mike handles septic capacity, zoning, and town approvals personally
  • 40+ years of relationships with every Plymouth County inspector
  • Single set day on your property — minimal disruption to the main house
  • Fixed price + timeline locked in writing before groundbreaking

"An ADU isn't a smaller project — it's the same engineering, the same permit work, the same craftsmanship as a full home, just in a tighter footprint. Families building ADUs deserve the same accountability we bring to a 4,000 sq ft custom build. They get it."

Mike Biviano
4th Generation · 40+ Years South Shore
Schedule Your Free ADU Consultation
What ADUs Are Used For

Four Ways
Plymouth County Families
Use ADUs.

Same shell, very different lives inside. The best ADU is the one designed around what your family actually needs — not a generic template.

01
In-Law Suite

Bring aging parents home without giving up privacy on either side. Single-floor layouts with wider doorways, walk-in showers, and zero stairs — designed for aging in place from day one.

02
Rental Income

Plymouth County has strong long-term rental demand for well-designed ADUs, and coastal towns command premiums on short-term platforms during summer. Many owners use rental income to recover a meaningful portion of their build cost.

03
Home Office / Studio

A real, separated workspace — not a corner of the dining room. Insulated, climate-controlled, hard-wired internet. Walk across the yard, close the door, do the work.

04
Guest House

Visiting family. College kids home for summer. Friends in town. A proper guest house means your main home stays your main home — no fold-out couches, no shared bathrooms.

05
Adult Children Returning

For families whose adult kids are saving for a first home or finishing graduate school. Privacy for both households without the cost of separate housing during a transitional season.

06
Property Value Add

A permitted, code-compliant ADU adds documented square footage and a separate income stream — both of which appraise. Well-designed ADUs typically support and grow your property's resale value.

The BMB ADU Build Process

From First Call
to ADU Move-In.

Same five-step process as a full modular home. Same fixed price. Same 8–12 week timeline. Mike runs every step — you stay focused on what the ADU is for.

01
Free Consultation + Site Walk

60 minutes with Mike on your property. He'll confirm zoning by-right eligibility, septic capacity, set-back requirements, and crane access — before anyone signs anything.

02
Design & Lock Your Price

Custom plans tailored to your use case — in-law, rental, office, guest. Price and 8–12 week timeline locked in writing before any work begins.

03
Permits + Factory Build

Mike submits ADU permits with the town while your unit is precision-built in a climate-controlled factory. Foundation and utility tie-ins happen on your site in parallel.

04
Crane Set Day

Your ADU arrives by truck and is set on the foundation in a single day. Mike's crew handles connections, finish work, exterior detailing, and any custom touches.

05
Final Inspection + Keys

Mike walks final inspection with the town. Certificate of occupancy issued. Whatever the ADU is for — parents, renters, your workshop — it's ready.

ADU-Specific Questions

Questions About
Building ADUs.

We build modular ADUs up to 900 square feet — that's the cap most Plymouth County towns allow under Massachusetts' updated 2024 ADU law. Sizes typically range from 400 sq ft (compact studio) up to the 900 sq ft maximum (2-bedroom with full kitchen and bath).
Modular ADUs are priced at the same $250 per square foot as our full custom modular homes. A 600 sq ft ADU is approximately $150,000. A 900 sq ft ADU is approximately $225,000. That includes Mike handling design, permits, factory build, foundation, crane set, and finish work — turnkey.
Most modular ADU projects move into the build phase within 2–3 weeks of signing, with the unit set on its foundation in a single day. From contract to keys is typically 8–12 weeks — the same timeline as a full modular home, because factory build and site prep happen in parallel.
Yes — every Plymouth County town has its own ADU bylaw, and the rules tightened (in favor of homeowners) with Massachusetts' 2024 statewide ADU reform. Mike handles all permitting, zoning verification, septic capacity confirmation, and town approvals as part of every ADU build. With 40+ years and personal relationships with every local inspector, he knows what each department requires before we submit.
Yes — and it's one of the most common reasons families build with us. Plymouth County has strong long-term rental demand for well-designed ADUs, and coastal towns typically command premiums on short-term rental platforms during summer. Many owners use rental income to recover a meaningful portion of their build cost over time — though the exact economics depend on your town, your unit's size, and how you choose to rent it.
Yes. Modular construction is ideal for occupied properties because the unit is built off-site in a climate-controlled factory while we prep your foundation. The on-site disruption is concentrated into a single set day plus a few weeks of finish work — versus 6–12 months of constant construction with traditional stick-built.
Biviano Modular Builders — Custom modular ADU
Free Consultation · ADU Project

Build Your
ADU
This Year.

8 consultation slots available per month. No obligation — just a 60-minute conversation with Mike, site walk, and a full cost breakdown for your ADU.

Call Mike Directly
Email
Begin Your ADU Build
Mike will respond within one business day.

No spam. No obligation. Mike typically responds same day.

ADUs Built Across the South Shore