ADU cost in Ashland, 2026
What an ADU costs in Ashland in 2026
A new detached ADU (accessory dwelling unit, also called a backyard cottage or granny unit) starts around $500 per square foot in Ashland and southern Jackson County in 2026, and most land at $550 to $600 per square foot or more. A 500 square foot detached ADU is most likely about $310,000, with a range of $249,000 to $375,000.
These figures come from our own ADU estimates, repriced to today’s labor, material and subcontractor costs. They include permits and the city’s system development charges. They are a ballpark, not a quote. Updated October 2026.
| ADU | Most likely | Range |
|---|---|---|
| 400 sq ft, detached, full kitchen | $255,000 | $206,000 to $310,000 |
| 500 sq ft, detached, full kitchen | $310,000 | $249,000 to $375,000 |
| 800 sq ft, detached, full kitchen | $470,000 | $375,000 to $565,000 |
| 500 sq ft guest house, kitchenette, no range | $295,000 | $236,000 to $355,000 |
| 500 sq ft, converted garage or outbuilding | $270,000 | $216,000 to $325,000 |
| 500 sq ft, carved out of the existing house | $137,000 | $109,000 to $164,000 |
A detached ADU is a small new home: a foundation, utilities, a kitchen and a bathroom on a small footprint. That is why it costs more per square foot than a full-size house.
Ask what your project would cost
What drives the cost
ADU or guest house
Without a cooking range, a unit is a guest house. A guest house shares the driveway, utilities and address with the main house, has a smaller kitchenette and costs less to permit.
New building or existing space
An ADU built inside the existing house, such as a basement or a wing, reuses the foundation, roof and most of the walls. It runs about $275 per square foot, about half the cost of a detached one.
Separate address, utilities and parking
A separate address usually means separate utilities. A separate address with its own driveway brings a 500 square foot ADU to about $325,000. Shared utilities and a shared driveway cost less.
The lot
Driving access to the building site keeps the cost down. A steep lot, materials carried in by hand, a septic system or a long run of new power line raise it.
Finish level
Simple finishes bring a 500 square foot ADU to about $255,000. Most of the price is the building itself, not the finishes.
Cottages we’ve worked on
- Church Street, Ashland. A detached guest cottage of about 420 square feet in a historic district near downtown. In 2015 the City of Ashland gave it a Historic Preservation Award.
- 8th Street, Ashland. A full remodel of a one-story back house in the Railroad District: an open kitchen and living room, a bedroom and a bathroom. It would cost about $205,000 to $340,000 to build today.
Ben can talk through whether an ADU, a guest house or an addition fits your lot and your plans best.
Rules worth knowing
Oregon law requires Ashland, Medford, Talent, Phoenix and Jacksonville to allow an ADU with a house on lots zoned for single-family homes. Cities cannot require you to live on the property or to add parking, except for vacation rentals. In Ashland an ADU needs only a building permit, and in single-family zones it can be up to half the size of the house, to a maximum of 1,000 square feet. Ashland does not allow ADUs to be rented for less than 30 days. We check the rules for your lot and handle the permits.
What these numbers don’t include
- Planning, which is billed hourly under its own agreement.
- Engineering and surveying, when a project needs them.
- Separate meters and utility connection fees.
- Decks and landings.
- Tree removal.
How we get to your number
- Ben meets you at your house. The first meeting is complimentary.
- We send a written description of the project and a cost range, at no charge.
- If the range fits what you want to invest, we start planning under an hourly planning agreement. Ben draws the building plans, and planning ends with your selections and a firm, fixed price.
Talk with us
Fill out the contact form; we get it right away and respond within a day. You can also call the office at 541-300-8118, Monday to Friday, 7 am to 3:30 pm, or email office@benthebuilderinc.com.