ADU Builder in Yarmouth, MA
Mussato Building Group designs, permits, and builds ADUs in Yarmouth, MA, from detached guest cottages to in-law suites and garage conversions. We are a family-owned general contractor founded in 2004, with more than 100 projects completed and a 5.0 rating from 21 Google reviews. We are based right here in South Yarmouth, and we work across Yarmouth Port, South Yarmouth, West Yarmouth, and Bass River.
- Family-owned since 2004
- Licensed + insured in MA
- 100+ projects completed
- 5.0 stars from 21 Google reviews
- BBB accredited
Building an ADU in Yarmouth
Yarmouth is our home town, running from the historic houses of Yarmouth Port on Route 6A to the neighborhoods along Bass River and Nantucket Sound.
State law allows one ADU of up to 900 square feet by right on most single-family lots, and that includes Yarmouth. What usually decides the project here is the lot and the septic system: an ADU with a bedroom adds to the bedroom count the system has to carry under Title 5, so we start with the Yarmouth Board of Health.
In the Old King’s Highway district of Yarmouth along Route 6A, a detached ADU that can be seen from the street also needs a certificate from the OKH committee, so we design the cottage to fit the historic houses around it.
“I’ve worked with Joe and his team on several projects and the workmanship is consistently excellent. Their attention to detail and the ease of communication is second to none. Highly recommended.”
ADU permits in Yarmouth
We prepare the drawings, file the applications, and schedule the inspections. Here is what a project like this usually needs:
- Building permit from the Yarmouth Building Department, and a certificate of occupancy at the end.
- Review by the Yarmouth Board of Health of septic capacity under Title 5 if the ADU adds a bedroom.
- Zoning review of setbacks, height, and lot coverage under the Yarmouth zoning bylaw.
- Conservation Commission review if the ADU is within 100 feet of a wetland, coastal bank, dune, or salt marsh.
- Flood-zone design if FEMA maps the lot in an AE or VE zone.
- A certificate from the Yarmouth Old King’s Highway committee if the ADU can be seen from a public way in the historic district.
- Detached ADUs and guest cottages
- Attached ADUs and in-law suites
- Garage and lower-level conversions
- Kitchens and bathrooms sized for small spaces
- Foundations, framing, and exteriors matched to the main house
- Heat, hot water, and electrical for a second dwelling
- Zoning, septic, and permit coordination
- Site work and paths between the houses
ADU Builder in Yarmouth: FAQ
Can I build an ADU in Yarmouth?
In most cases, yes. State law allows one ADU of up to 900 square feet, or half the size of the main house if that is smaller, by right on single-family lots in Yarmouth. Setbacks, septic capacity, Old King’s Highway review, and conservation rules still apply, so we check your lot first.
Do you build ADUs in Yarmouth Port and South Yarmouth?
Yes. We build detached and attached ADUs all over Yarmouth, including Yarmouth Port, South Yarmouth, West Yarmouth, and Bass River. We are based right here in South Yarmouth.
Will my septic system handle an ADU in Yarmouth?
Most Yarmouth homes are on septic systems. On septic, Title 5 sizes the system by bedroom count, so an ADU with a bedroom can mean a septic upgrade. The Yarmouth Board of Health reviews it before the building permit.
Can I rent out an ADU in Yarmouth?
Long-term rentals are allowed, and the town cannot require you to live on the property. Short-term rentals of an ADU can be restricted by the town, so check the Yarmouth rules before you plan on summer rentals.
More in and around Yarmouth
- ADU Builder in Dennis, MADennis Village, East Dennis, South Dennis
- ADU Builder in Barnstable, MAHyannis, Barnstable Village, West Barnstable
- ADU Builder in Harwich, MAHarwich Center, Harwich Port, West Harwich
- Deck Builder in Yarmouth, MANew decks, deck replacement, stairs, and railings
- Deck Replacement in Yarmouth, MATear-out and rebuild of old, soft, or unsafe decks
- Basement Finishing in Yarmouth, MAMedia rooms, gyms, bars, guest suites, and egress windows
- Basement Remodeling in Yarmouth, MADated or damp finished basements rebuilt from the foundation in
- Basement Egress Windows in Yarmouth, MACode-size escape windows and window wells for basement bedrooms
- Bathroom Remodeling in Yarmouth, MATile showers, tubs, vanities, and powder rooms
- Kitchen Remodeling in Yarmouth, MALayouts, islands, custom cabinetry, and counters
- ADU Builder in Barnstable County, MAAll 15 towns of the county
- ADU Builder on Cape CodThe whole Cape, from Bourne to Provincetown
- The Massachusetts ADU Law: What the 900-Square-Foot Rule MeansGuide
- How Much Does an ADU Cost on Cape Cod?Guide
Tell Us About Your Project
© 2026 Mussato Building Group Inc. All rights reserved. Yarmouth, MA, Serving Cape Cod.