What an ADU actually costs in Maine & New Hampshire in 2026
Langone Site Services turn-key ADU pricing in 2026 ranges from $135,000 for our smallest studio model to $294,300 for our largest 2-bed, 2-bath. These are all-in, turn-key numbers on standard sites — not estimates that grow once permits start.
Our 7 ADU models and starting prices
- The Bean — 384 sq ft, 1 bed, 1 bath — from $135,000. Studio-style layout, perfect as a guest cottage, home office, or first rental — tour The Bean.
- The Newfield — 600 sq ft, 1 bed, 1 bath — from $179,000. Our most popular backyard cottage layout (see The Newfield).
- The Summit — 654 sq ft, 1 bed, 1 bath — from $215,000. A slightly larger footprint with a more open great-room feel.
- The Bentley — 600 sq ft, 1 bed, 1 bath — from $255,000. Premium one-bed with an attached garage — the full finish package for full-time living.
- The Spruce — 882 sq ft, 2 bed, 2 bath — from $265,000. A full 2-bedroom home. Popular for multi-generational living — details on The Spruce.
- The Washington — 896 sq ft, 2 bed, 1 bath — from $279,000. Larger living space, ideal for year-round rental.
- Ellas Retreat — 981 sq ft, 2 bed, 2 bath — from $294,300. Our flagship — full-size kitchen, walk-in shower, large living area. Explore Ellas Retreat.
What's included in the turn-key price
Every ADU package includes:
- Monolithic slab foundation, excavated and poured
- ZIP wall + roof sheathing with 30-year architectural shingles
- Matthew's Brothers Windows & Doors
- Vinyl siding in your chosen color
- Mitsubishi mini-split heating and cooling
- On-demand hot water
- Starlink-ready wiring (rural connectivity ready out of the box)
- LVP flooring throughout
- Tongue-and-groove pine ceilings
- Hardwood cabinets with granite counters
- Delta plumbing fixtures
- Recessed LED lighting
- R49 ceiling + R23 wall insulation
What can push price above the starting number
- Site conditions. Heavy clay soil, high water table, bedrock close to surface, or long utility runs can add $15k–$40k.
- Septic. If your lot needs its own septic, add $18k–$45k depending on soil and system type.
- Premium finishes. Upgrading to hardwood floors, quartz, or custom cabinets can add $10k–$30k.
- Lot access. Tight lots requiring specialty equipment add $5k–$15k.
How Langone's pricing compares
We're transparent with pricing because our competitors aren't. Most builders won't give you a number until they've done a full site visit and design. Our 7 standard models mean we know our real costs and can quote honestly on day one.
Want a real ballpark for your lot? Use our instant pricing calculator — it takes 2 minutes and gives you a real range based on our actual 2026 job data.
Or book a free 20-minute land or build consult with Dylan directly.
Frequently asked questions
What's the cheapest way to build an ADU in Maine or NH?
A compact footprint on a straightforward lot. Our smallest model, The Bean (384 sq ft, 1 bed), starts at $135,000 all-in. Clean-percing soils, utilities near the site, and easy access all pull the final number toward the low end.
Does the price include site work and septic?
Yes — that is the difference between us and modular ADU companies. We own the excavation fleet and install septic ourselves, so site prep, foundation, utility runs, and permits are in the number you see, not excluded from it.
How much rental income can an ADU generate?
A 600–900 sq ft ADU in our service area typically rents long-term for $1,400–$1,900 per month, with lakeside and Seacoast markets higher — and short-term rates well above that in season. See our ADU rental income article for real numbers.
How do people pay for an ADU?
The most common routes are a HELOC on the main house, a construction loan that converts to a mortgage, or a DSCR loan qualified on projected rent for investors. We also offer monthly payment options through Hearth — see our financing page.
How long does an ADU take to build?
Most of our builds finish in about 8 weeks once permits are in hand and utilities are at the property line — excavation through final interior finish, one crew the whole way.
Skip the guesswork — get instant pricing.
Our 2-minute calculator gives you a real ballpark for any project type in Maine or New Hampshire.
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