Add extra space and value to your property
You might need extra space for your in-laws, are looking to make some additional income, or simply want more living space. Whatever your motivation, we can help you design and build the perfect ADU for you
The different types of ADUs
- Basement conversions
- Single story backyard cottage ADUs
- Two story backyard cottage ADUs
- Two story ADUs with a garage underneath
- ADUs attached to a home
Our ADU Besign+Build Process
Planning is a big part of building an ADU. Here are a few steps that go into the process:
- Feasibility and planning study - can I build it here? How large can I build it, what can it look like?
- Permitting process for an ADU:
- Surveys
- Planning and Zoning
- 2-6 months of review prior to construction
Once the permits and feasibility are approved, we can move on to our design and build stages.
Average costs for ADUs
As you can imagine, costs vary widely based on the type of ADU you're looking to build. Here are some average costs for various ADU categories:
- Basement conversions: $100,000-$200,000
- Single story backyard cottage: $125,000-$300,000
- Two story backyard cottage: $175,000-$500,000
- Two story ADUs + garage underneath: $175,000-$500,000
- ADU addition attached to a home: $125,000-$300,000
Check out some of our recent ADU projects below!
Our recent ADU projects in portland and sw washington
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!"