Why Choose Lamont Bros. for Your Portland Home Addition?

A home addition affects far more than square footage. It must work with your existing structure, improve the way your home functions, and feel like it has always belonged there. That requires design, engineering, permitting, budgeting, and construction decisions to support the same plan.

Lamont Bros. brings those responsibilities together through one accountable design-build team. We help you evaluate the possibilities, understand the tradeoffs, and make informed decisions before construction begins. Then we carry the design through the build, reducing the gaps and surprises that can occur when homeowners must coordinate separate firms.

Explore our completed home additions to see how we have expanded Portland-area homes while respecting their existing character. When you are ready to discuss what could work for your home, schedule a consultation.

We used Lamont Bros. in 2020 to do a major addition on our home. It was a difficult decision. Should we invest to make our home fit our growing family's needs or move to a newer, bigger home? Now, with the benefit of hindsight, we are so happy we chose to do the addition. Our space needs are so much better met and we get to stay in a great neighborhood.

We added about 225 square feet to a 90 year old home, going from a tight, old kitchen that doubled as a hallway in the middle of our house to a big open space that connects right to our backyard. It's amazing how the home looks like it's been that way forever. It all tied together just as we envisioned it and it even managed to surprise us in the ways it beneficially impacted the way we use other spaces in our home.

There will be challenges along the way anytime you do a major project. It's virtually impossible to get all the planning 100% right and anyone considering something like this should know that going in. What you need is a partner that acknowledges that and works with you every step of the way. We had that from Lamont Bros. Thanks to Paddie and Eddie who were there virtually every step of the way. They helped us live with a hole in the middle of our house by taking the work seriously, getting it done as close to on time as possible and communicating with us along the way.

I'd say let's do it again soon, buuuuut, I think we're going to kick back and enjoy the outcome for a lifetime or two.  Nick - Google Review

Lamont Brothers did a major 2 story addition/remodel job for us last summer, and we could not be happier with the work that they did. We had a second floor room added, one other second floor room expanded and a closet added, a roughed in bathroom added, a main floor bedroom expanded and the main floor layout completely changed, including a full bathroom remodel. Opening up an older house is always difficult, and complicating the work was the fact that we lived in the house for most of the construction (only around 400 sq ft of the house was not being touched by the project)- which meant that most of the construction was happening with my wife and 6 young children around the construction site. Not only did the workers keep my family safe, the guys actually took time to explain the work to my incredibly curious kids and on a few occasions let them take part in some of the activities (all safe, age appropriate, and with our consent, of course). By the end of the project, the workers felt like family members. Major remodels are always full of issues and we encountered our fair share of them, but the company always worked hard to provide a resolution that we felt was fair, or more often than not actually in our favor. We look forward to having them back to complete additional projects (kitchen and bathroom remodels) in the future. We've got nothing but good words about these guys. Alan - Houzz

How Much Do Home Additions Cost in Portland?

Home addition costs in Portland typically range from $100,000 to $400,000+, depending on size, structural complexity, and finish level. Second-story additions and kitchen expansions are generally more expensive due to engineering and mechanical integration.

Typical Portland Home Addition Cost Ranges

  • Small bump-out addition: $100,000 - $175,000

  • Kitchen or living room expansion: $175,000 - $275,000

  • Primary suite addition: $200,000 - $350,000

  • Second-story addition: $250,000 - $400,000+

What affects cost most?

  • Structural engineering requirements
  • Foundation work
  • Roof modifications
  • Plumbing & electrical upgrades
  • Finish quality and custom features

For an accurate estimate, a feasibility consultation and site evaluation are required.

Want a personalized estimate? Try Our Home Addition Cost Calculator

Wonderful experience! Everyone was professional, friendly and helpful. These folks were not cheap, but they do deliver good value (you get what you pay for). They provided several initial designs (addition + remodel, kitchen remodel only, kitchen plus utility area remodel), then once we selected one they were very helpful with all of the design choices. Once the job started, the crew were amazing! Hard-working and friendly, they really did a wonderful job trying to minimize the inevitable disruptions of a major remodel (while I was working from home). The job finished several months ago, and we could not be more satisfied. Jon - Houzz

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See Why We're Portland's Favorite Home Addition Contractor

Building a custom home addition in Portland is made easy with our design-build process. 

 

Custom Portland Home Additions

These additions across the Portland metro area include second-story additions, basement build-outs, built extra bathrooms, and more. 

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Portland | Home Addition Construction

Frequently Asked Questions

How much does a 500 sq ft home addition cost in Portland?

A 500 square foot addition in Portland typically costs between $175,000 and $300,000, depending on structural complexity, finish level, and utility integration.

Kitchen and bathroom additions trend toward the higher end due to plumbing and cabinetry costs.

Is it cheaper to build up or build out in Portland?

Building out is often less expensive structurally, but it requires adequate lot space and setback compliance. Building up (adding a second story) avoids expanding the footprint but requires significant structural reinforcement. The most cost-effective option depends on lot size, foundation capacity, and zoning.

How long does a home addition take in Portland?

From design through construction, most home additions take 6 to 12 months. Permitting alone can take several weeks to a few months, depending on project complexity and city workload.

What's the difference between a home addition and an ADU?

A home addition expands your existing home and shares utilities and living space. An ADU (Accessory Dwelling Unit) is a separate, self-contained living unit with its own kitchen and bathroom. Portland has specific zoning regulations governing ADUs.

Do home additions increase property value in Portland?

Yes. Well-designed home additions often increase resale value, especially when adding bedrooms, bathrooms, or expanding kitchens. Return on investment depends on neighborhood market conditions and project quality.

Can you live in your home during an addition project?

In many cases, yes. However, for large structural projects like second-story additions, temporary relocation may be recommended for safety and efficiency.

What neighborhoods in Portland do you serve?

Lamont Bros. provides custom home additions throughout Portland, including neighborhoods such as Alameda, Alberta Arts District, Arbor Lodge, Beaumont-Wilshire, Boise, Brentwood-Darlington, Brooklyn, Buckman, Concordia, Creston-Kenilworth, Eastmoreland, Forest Heights, Goose Hollow, Grant Park, Hawthorne, Hillsdale, Irvington, Laurelhurst, Lents, Maplewood, Montavilla, Multnomah Village, Nob Hill, Overlook, Pearl District, Richmond, Sellwood-Moreland, St. Johns, Sunnyside, University Park, West Hills, and Woodstock.

In addition to serving Portland neighborhoods, we also complete home additions in surrounding areas including Beaverton, Lake Oswego, West Linn, Tigard, Tualatin, Milwaukie, Happy Valley, and other nearby communities throughout the greater Portland metro area.

Award-Winning Design

2026 NARI Remodeler of the Year 

Oregon Home Structure and Style Winner

Delighted Clients

4.7 rating across hundreds of reviews

Houzz Best of Service every year since 2016

Trusted Expertise

850+ remodeling projects since 2008

Licensed in Oregon and Washington