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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.

Note: Prices listed below are adjusted for inflation.

ADU Case Study 1: Garage Conversion Remodel

Year Remodeled: 2018

Remodel Cost:        $98,000

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

Year Remodeled: 2017

Remodel Cost:        $266,000

Project goals:

  • Remodel basement into fully legal ADU
  • Install new basement entrance & patio
  • New heated floors in concrete
  • New heating system, water heaters, & electrical wiring
adu floorplan
Hawthorne Basement Accessory Dwelling Unit
Hawthorne Basement Accessory Dwelling Unit

ADU Case Study 3: Detached ADU

Year Remodeled: 2018

Remodel Cost:        $312,000

Project goals:

  • Construct 2 Story ADU
  • 1 Bedroom apartment with kitchen & full bath
  • Open floor plan with great room downstairs
  • Outdoor Storage Space
adu floorplan
Woodlawn ADU
Portland ADU Kitchen

ADU Case Study 4: 2 vs. 1 Story

2 Story Option

Year Remodeled: Proposed 2021, Not Built

Remodel Cost:        $665,000

Project goals:

  • 800 sq. ft. + 114 sq. ft. patio
  • 2 bedrooms
  • 1 full bath & 1/2 bath + laundry
  • Kitchen with quartz countertop & tile backsplash 
  • Luxury vinyl plank flooring
  • Separate electric meter
2storyfloor1
2storyfloor2
THIS IS A TEST
2storykitchen

1 Story Option

Year Remodeled: Proposed 2021, Not Built

Remodel Cost:        $495,000

Project goals:

  • 600 sq. ft. + 114 sq. ft. patio
  • 1 bedroom
  • 1 full + laundry
  • Kitchen with quartz countertop & tile backsplash 
  • Luxury vinyl plank flooring
  • Separate electric meter
1storydesign
1storyext
1storykitchen

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