In Lake Oswego, a home addition runs into site rules before design: setbacks, lot coverage, the city tree code, sloped lots and sometimes HOA review. Serden Group checks feasibility first, then designs, permits and builds the addition with one project manager.
The best addition for a Lake Oswego home is often decided by the trees and the slope, not the floor plan. We map setbacks, protected trees and grades before sketching, so the design you fall in love with is one the city will approve and the lot can hold.
Rear bump-outs, kitchen and family room expansions, primary suites, second stories and garage conversions — or an ADU in Lake Oswego when a separate unit fits better.
Common on Lake Grove ranches and Westlake two-stories. Engineering, foundation work, new stair, full reroof.
Kitchen, dining and family room expansions where lot coverage, setbacks and protected trees set the footprint.
Bedroom, ensuite bath and closet added up or back, detailed to match the original house.
Basement, garage and detached units permitted as legal dwellings with their own kitchen and entry.
We check your zone’s setbacks and lot coverage, protected trees, slope and any HOA rules before design, so there are no late surprises.
Plans, elevations and stamped structural drawings, a pre-application conference with the city when the project calls for one, and tree-protection plans.
Foundation, framing, roof tie-in, systems and matched finishes, with tree fencing inspected before the building permit is issued.
Why Homeowners Choose Serden
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Read all 400+ reviewsThe project was finished on time and within budget. There was outstanding communication from start to finish and meticulous attention to detail. They are a contractor that goes the extra mile and I would definitely recommend.
Fantastic experience! They renovated my entire home with new floors, a full kitchen remodel, and a bathroom upgrade. The kitchen looks amazing with new cabinets, countertop, and appliances, and the bathroom to shower conversion turned out beautifully. Great quality work, finished on time, easy to communicate with, and their pricing was very competitive. Highly recommend!
We were very happy with the workmanship on our upstairs, downstairs and stairs flooring. Very friendly and were very accommodating to our home schedule and would recommend them to anybody who needs work to be done in their home
Serden remodeled our kitchen, dining room, living room and entry way. Dennis and Alex were especially friendly and easy to communicate with. Every person we had contact with was professional and did quality work. When unexpected issues came up, they solved the problems efficiently so we didn't have to stress about anything. They worked really hard to make sure we were happy at each step of the process. We love our new living space!
I purchased my first home a couple years ago, which was a time capsule from the 60s/70s. I got multiple quotes on getting my house updated. I of course wanted the updates to be budget friendly, but quality enough to last for years to come. Serden Group helped make suggestions that saved me money (to no benefit to themselves). With some of the other quotes I received I couldn't understand where so much of the cost was coming from and the quotes themselves were not clear in what I was being charged for. Serden Group however was very transparent in their pricing. The work they did is absolutely beautiful. Communication was consistent and timely. Their crew is incredibly kind and professional and cleaned up everyday. I think the scariest thing for most people getting work done our their homes is finding a trust worthy company to do so. There are too many occasions of companies having inflated pricing, hidden expenses, shoddy work, or poor communication. If you're looking for a company you can trust and to treat your home with the best care, give these guys a call.
We have used Serden Team for 3 projects. They remodeled our master bedroom and bathroom, refaced kitchen cabinets and built a beautiful surround for my refrigerator so it looks built in and remodeled a secondary bathroom. Their work is fantastic. They are easy to work with and communication is the best. I can trust them to do a great job and do the work properly the first time. Wonderful company and will refer them gladly.
They did an excellent job. They were fast and professional. They installed all new doors throughout my house, raised the floor in my family room and office, installed new flooring, and painted both rooms. It looks wonderful. I will be so happy to use the rooms once everything is put back where I want it. We have more work we want done in the future and I will definitely be hiring these guys again.
Serden did a great job on my vacation home in WA. They transformed the property, I had all my floors and windows changed out. Everything looks beautiful, up to date and modern. I will be using them again to remodel my kitchen and bathroom. The whole experience was easy and quick.
We hired Serden and their team to do a complete remodel of our new home that was very outdated. The work they did was incredible! They were very professional, timely, and the attention to detail on the work is amazing. We are so impressed and highly recommend!
Thank you for your quick response. Also, a big Thank You for helping me make my dream house come true, I never expected my home to become so beautiful. Great job. I will recommend you to my friends.
Serden Group and their crews Had done an awesome job remodeling my house. I am very pleased with the outcome. They were very professional and on time. I would definitely use their service again and recommend them to families and friends.
The remodeling team from Serden Group did a very good and professional job at my home. They completely remodeled the kitchen and all the dining and living areas, everything looks like a brand new home! They also installed new patio cover and deck which we already enjoy. Thank you! I definitely recommend them, they are experts, friendly and know what they are doing.
Serden Group remodeled kitchen and all bathrooms in my house. I am very happy with the quality of their work and the way they were informing me on every stage of the project. They also provided design ideas and suggested colors and materials. I needed the full service from design to completion. I am very satisfied.
Cannot be happier with the outcome of our remodel! Professional and communicative contractors. We will go back to Serden for all of our remodeling needs, other contractors do not compare. Yes- we have wasted time and money on others, before finding Serden.
I recently worked with Serden Group on my condo renovation, which included replacing floors, removing popcorn from ceilings, and replacing kitchen counters and cabinets. I loved working with Dennis and David. Dennis helped with input on the kitchen design and was great in helping to reduce stress. They were patient with me and my questions. Their crew was great. And as messy of a job that it was, they managed to leave the place clean when they left for the night. The work was great, and they care for the space as if it;s their own.
This company did a great job on an extensive remodel of a mid 70s home. They upgraded the electrical, plumbing, removed walls, remodeled the bathrooms and kitchen, and put in all new tile flooring. All the home issues were addressed, and we could not be any happier.
Local Knowledge · Lake Oswego, OR
These are the site and code questions we answer before design, because they decide what size and shape of addition is realistic.
A home addition in Lake Oswego, OR typically costs $110,000–$200,000 for a bump-out, $200,000–$350,000 for a primary suite and $300,000–$500,000 or more for a second story in 2026. Plan on 2–4 months for design and permits and 4–10 months of construction. Additions need City of Lake Oswego building permits, and trees 6 inches or more in diameter are protected.
Lake Oswego protects trees 6 inches or more in diameter at 4.5 ft, and that often decides where an addition can go.
Each residential zone sets its own setbacks, lot coverage and height limits, and many lots here slope.
Going up saves lot coverage and trees but costs more per square foot.
Some approvals come on top of the city permit.
| Scope | Typical cost | Timeline |
|---|---|---|
| Bump-out or single room | $110K–$200K | 4–6 months build |
| Primary suite addition | $200K–$350K | 5–8 months build |
| Second story | $300K–$500K+ | 7–10 months build |
| Design, engineering and permits | Varies by scope | 2–4 months |
Every addition needs a City of Lake Oswego building permit, with trade permits for plumbing, electrical and mechanical. Plans typically include floor plans, elevations, structural calculations and energy documentation. Larger or more complex projects may need a pre-application conference with planning staff first.
We prepare the submittal, coordinate the arborist and engineer, respond to plan-review comments, and schedule inspections.
From First Addition and Old Town to Lake Grove, Westlake, Palisades and Mountain Park — plus West Linn, Dunthorpe and Tualatin. We know where the tree code, sloped lots and HOA review shape what can be built. Our Lake Oswego office is at 333 S State St, Lake Oswego, OR 97034 — design consultations by appointment.
Free in-home consultation — home additions in Lake Oswego, OR & Clackamas County
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Questions? Call (360) 836-7775
Honest 2026 ranges for finished, permitted additions, including design, engineering and permits. Sloped lots and tree protection can add to site costs; we price those after feasibility.
Ranges are planning figures, not quotes. Your fixed price follows feasibility and a written scope.
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Everything Serden Group builds in Lake Oswego, the same service in nearby cities, and the planning guides clients read before they start.
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