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ADU Costs

Average Portland ADU Costs

ADUs are one of the most effective ways to add space and value to your existing property. Whether you're converting a garage, repurposing a basement, or want to build a detached ADU, we can help you get there.

ADU Case Study 1: Garage Conversion Remodel

Year Remodeled: 2018

Original cost to remodel:      $87,968

Cost to remodel in 2021:        $98,006

Project goals:

  • Convert existing garage into a legal ADU rental unit
  • Remodel existing bathroom
  • Work with existing plumbing, electrical, & drywall
  • 1 bedroom apartment with kitchenette and bathroom
adu floorplan
ritter adu
ritter adu
ritter adu

ADU Case Study 2: Basement conversion

  • Full basement remodel and legal ADU
  • New entrance to basement with patio
  • Heated concrete floor
  • New concrete floor in partial basement
  • Bathroom
  • Kitchen
  • New heating system for the ADU and the main home
  • New hot water heaters
  • Additional electrical work for main home
  • Cost: $265,874
adu floorplan
Hawthorne Basement Accessory Dwelling Unit
Hawthorne Basement Accessory Dwelling Unit

ADU Case Study 3: Detached ADU

  • Two Story ADU with bedroom
  • New bathroom
  • Great room
  • Outdoor storage space
  • Cost: $312,356
adu floorplan
Woodlawn ADU
Portland ADU Kitchen

Client testimonials

"We couldn't be more happy with the finished product. We have been enjoying our new living space for a full year now and love it just as much as the day it was completed!"

Robert and Diane / SW Portland Kitchen Remodel

"We are thrilled, and the work is above our expectations! We're extremely happy with the quality and the processes Lamont Bros. had in place to complete our goals. All workers were friendly, polite, communicated effectively, were here on time, and conveyed the status of the job at all times."

Mark and Wilda / Oregon City Portland Kitchen & Bathroom Remodel

"I wish I could leave a higher rating than 5 stars! These guys set the bar extremely high in terms of customer service and quality work. Joseph is incredibly knowledgeable and helpful and helped me do some structural analysis on my house. Everyone I've worked with at Lamont Bros. is awesome! I will definitely use these guys again!"

Dan / SE Portland Multiple Projects

"After working with Joseph & his crew from the Lamont Bros., we are enjoying a beautiful new kitchen. We appreciated the design process & the hard-working team who completed our work. Special kudos to Rebecca who painstakingly mounted our tile back splash -- first thing everyone notices!"

Kathy / SE Portland Kitchen and Outdoor Space

"We had a tree fall on our house at the worst possible time of year. We contacted Lamont Bros. and they responded immediately. We had a quote in a very reasonable time frame,  and they dealt with all the insurance issues. Lamont Bros. managed to get the job done when they said it would be done. And done right the first time."

Dan / Clackamas County Structural Repair

"After looking for a good local company to add a craft room to our ranch style home, we found Lamont Bros and couldn't be happier with the quality of the work and performance of the crew. The design Joseph came up with was better than we hoped for. We highly recommend this company to anyone looking for a good fair deal. Thank you Joseph and crew!"

Susan / Oregon City Addition