Home Additions in Greater Seattle

Need more space but love your neighborhood? CH&R Inc. builds room additions, second stories, and bump-outs that expand your home while maintaining its character. Serving Seattle, Bellevue, and the Eastside for over 30 years.

Stone fireplace construction for home addition in Seattle

Why Add On Instead of Moving?

  • Keep your neighborhood, schools, and commute
  • Avoid Seattle's competitive real estate market
  • Build exactly what your family needs
  • Increase your home's value

Seattle Home Addition Services

Seattle real estate prices make adding onto your current home an attractive alternative to buying bigger. The average home in Seattle, Bellevue, or Kirkland now costs well over a million dollars. For many homeowners, building an addition costs less than the transaction costs of selling and buying.

We have built additions throughout the Seattle area, from expanding small Craftsman bungalows in Fremont to adding second stories to mid-century ramblers in Mercer Island. Each project is different, and we work with you and often an architect to design an addition that looks like it was always part of your home.

Types of Additions We Build

  • Ground-floor additions that expand into side or back yards
  • Second story additions that add bedrooms and bathrooms above existing space
  • Bump-outs that extend a room by a few feet for more usable space
  • Garage conversions that transform underused garages into living space
  • In-law suites and accessory dwelling units attached to your home
  • Sunrooms and four-season rooms that bring the outdoors in
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Planning Your Seattle Home Addition

Adding onto a home in the Seattle area involves several considerations. We help you navigate all of them.

Zoning and Setbacks

Seattle, Bellevue, Kirkland, and other jurisdictions have rules about how close you can build to property lines, how much of your lot can be covered, and how tall structures can be. We research these requirements early so you know what is possible on your lot.

Permits and Inspections

All home additions require building permits. In Seattle, this means working with SDCI. We handle permit applications, plan reviews, and coordinate all required inspections throughout the project.

Architectural Design

Your addition should look like it belongs. We work with architects when needed to design additions that match your home's roofline, siding, windows, and overall character.

Foundation Requirements

Second story additions often require foundation reinforcement. Ground-floor additions need new foundations. Seattle's soil conditions vary by neighborhood, and we work with structural engineers to get this right.

Popular Home Addition Projects

Here are the additions we build most often for Seattle area homeowners.

Primary Suite Additions

Many older Seattle homes have small primary bedrooms with no ensuite bathroom. A primary suite addition adds a spacious bedroom, walk-in closet, and full bathroom. This can be built as a ground-floor addition or as part of a second story.

Kitchen Expansions

A bump-out or small addition can transform a cramped galley kitchen into an open, functional space. Even adding 4-6 feet gives room for an island, better traffic flow, and space for the family to gather.

Family Room Additions

Post-war ramblers often lack a proper family room. A ground-floor addition off the kitchen creates space for everyday living separate from a formal living room.

Second Story Additions

When your lot cannot accommodate a ground-floor addition, building up is the answer. Second story additions typically add bedrooms and bathrooms, often doubling your home's square footage. These are complex projects that require structural engineering and careful design.

In-Law Suites

Multi-generational living is increasingly common. An in-law suite provides a private bedroom, bathroom, and often a small kitchen or kitchenette for parents or adult children. These can be attached to your main home or built as detached units.

Home Office Additions

Remote work is here to stay. A dedicated home office addition provides separation from household distractions and a professional space for video calls. These can be small bump-outs or larger dedicated rooms.

Home Addition FAQs

Home addition costs depend on the type of addition, size, and complexity. Bump-outs cost less than ground-floor additions, and second story additions involve more structural work. Foundation requirements, finishes, and site conditions all affect pricing. We provide detailed estimates after visiting your home and understanding your project scope.

Home additions typically take 3-6 months from permit approval to completion. Small bump-outs might take 2-3 months. Larger ground-floor additions run 4-5 months. Second story additions can take 5-6 months or longer. The permitting process in Seattle can add 2-4 months before construction begins, so plan accordingly.

It depends on the complexity. Small bump-outs and straightforward additions often do not require an architect. Larger additions, second stories, and projects with design challenges benefit from architectural involvement. We can recommend architects we have worked with successfully or work with your architect if you already have one.

For most additions, yes. Ground-floor additions and bump-outs usually allow you to stay in your home throughout construction. Second story additions are more disruptive and some homeowners choose to relocate temporarily, especially during framing and roofing phases. We discuss this during planning so you know what to expect.

That is our goal. We carefully match rooflines, siding, windows, and trim details so your addition looks original. Sometimes exact siding matches are not available, and we might need to re-side portions of your home for a seamless appearance. We discuss these details during design so there are no surprises.

Related Services

Whole Home Remodel

Adding on and renovating existing spaces at the same time? A whole home remodel coordinates everything for consistent design.

Learn more →

Outdoor Living

Backyard cottages and detached structures provide additional space without connecting to your main home.

Learn more →

Custom New Construction

If your lot and goals would be better served by a new build, we construct custom homes from the ground up.

Learn more →

Ready to Expand Your Home?

Contact us for a free consultation. We serve Seattle, Bellevue, Kirkland, Redmond, Mercer Island, and communities throughout King and Snohomish counties.

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