Home Additions

Add the space your home is missing — primary suites, second stories, family-room additions, and kitchen bump-outs, designed and built by one licensed Washington contractor. Blue Lake handles architecture, engineering, permits, and construction on a single fixed-price contract.

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Woodinville

Master bed and bathroom addition.

White house with dark brown roof undergoing roof renovation with scaffolding and tiles stacked on roof.

Fall City

Ada extension side of the house.

Modern white house with large windows, a brown roof, and a paved pathway surrounded by green grass.

Burien

Second story extension for a sunroom.

Wooden framing of house extension under construction with two workers on top and ladders around.

Check Out Some of Our Latest Work.

In the gallery, are some of the projects we have done for clients in the various service areas we offer.

Modern office meeting room with concrete table, chairs, shelves with books, and industrial style decor.

Long wooden fence with metal posts along a sidewalk and grass in a residential area.

Modern garage with a pool table, bike on wall, and a Tesla parked outside glass garage door.

Modern basement with wood floors, two patterned chairs, a white sectional sofa, and a gray patterned rug.

Black metal fence separating grassy area with trees from a yard with shrubs and a house in the background.

Open kitchen and living area with laminate wood flooring, white cabinets, and stainless steel appliances.

Modern outdoor patio with wooden furniture, cushions, potted plants, and a hot tub beside a white house.

Three white-framed sash windows looking out to a sunlit backyard with a wooden fence and house beyond.

Modern small house with white and wood-paneled exterior, tall windows, and black door in a garden setting.

Empty wooden deck with railing surrounded by green pine trees in sunny outdoor setting.

Glass sunroom attached to white house under construction with ladder and tools on ground.

Side view of a gray house with white trim, windows, and bushes along the foundation on a sunny day.

Wet stone patio with stairs leading to a wooden deck and green lawn with bushes in the background.

Covered patio with brown cushioned chairs, a fireplace, ceiling fan, and a swimming pool in the background.

Wooden frame structure being built in front of a large two-story house with gray siding and white trim.

Glass sunroom attached to brick house with wicker furniture and ceiling fans, surrounded by greenery.

Back patio with wooden deck and pergola attached to beige house under clear blue sky.

Modern kitchen with white upper cabinets, green lower cabinets, stainless steel appliances, and wood flooring.

Modern kitchen with white cabinets, marble island, stainless steel appliances, and hexagon tile backsplash.

Shower with blue and gold marble tiles, hexagonal floor tiles, built-in shelf with bottles, and bronze showerhead.

Small bathroom with marble floor, black vanity, lit mirror, toilet, and bathtub with floral shower curtain.

Worker on ladder painting upper part of house beige while lower part is brown under blue sky.

A person sweeping a two-level wooden deck outside a gray house with white trim windows.

Corner bathtub with gray tiles, silver faucet, soap dish, and large windows showing autumn trees outside.

Modern glass shower with marble tile walls and hexagonal floor tiles, built-in seat, and silver fixtures.

White right arrow on teal circular background, indicating forward or next action.

Why Choose Blue Lake?

Blue outline of a house with a location pin symbol on the left side.

Local Family-Owned Expertise in Washington State

We, a locally family-owned and operated renovation company in Washington state, bring a wealth of experience. We've successfully completed thousands of construction projects. When you choose us, you're not only selecting a team; you're partnering with experts who understand the local scene, offering top-notch service with a straightforward and reliable approach.

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Collaborative Design Precision

We collaborate closely with architects and designers in the initial stages, ensuring a workable concept within budget before committing to the developed design. This collaborative approach not only saves time but also minimizes re-design costs. Our builders are prepared to tackle any task, motivated to surpass your expectations.

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Innovative Communication and Transparency

To enhance communication and transparency, we've developed a construction project management app. This tool provides instant updates for all parties involved, giving you a hands-on experience with the build of your home. This commitment to efficient collaboration and technological innovation sets us apart, ensuring a seamless and satisfying construction experience for our clients.

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Stress-Free Build Experience

You will have one point of contact who manages all aspects of your project from planning to completion. Their goal is to create an exciting and stress-free experience by understanding your requirements, delivering a quality service through clear communication to you and the trades, and then project managing the build.

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Fixed Price and Project Duration Assurance

We provide you with a detailed scope of work with a fixed price and a fixed duration. We deliver on time and on budget.

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Total Peace of Mind

We take care of everything from the moment we meet you until we deliver a finished and professionally cleaned beautiful home, all with great attention to customer satisfaction.

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Unified and Skilled Teamwork

Our team includes builders, handymen, plumbers, electricians, painters, carpet installers, kitchen makers, landscape experts, and professional cleaners. All working together and communicating on one platform.

Two-story house with a beige garage door, stone accents, lawn, and wooden fence under a blue sky.

Not sure how to start? Get a free consultation.

One of our experts will get back to you as soon as possible.

(206) 786-5988

Home Addition Questions, Answered

How much does a home addition cost in Bellevue or Seattle?

Most ground-level room additions in the Seattle–Bellevue area run $350–$550 per square foot — typically $120,000–$200,000 for a 300–400 sq ft addition. Primary suite additions run $180,000–$300,000+, and second-story additions $300,000–$600,000+ depending on structural work. Blue Lake builds on a fixed-price, fixed-duration contract, so the number you sign is the number you pay.

How long does a home addition take?

Plan on 4–8 months of construction depending on scope, after 2–4 months of design, engineering, and permitting. A realistic start-to-finish timeline is 6–12 months, and your contract includes a fixed completion date.

Do I need a permit for a home addition?

Yes — additions require full building permits in every Washington city, and most need structural engineering as well. We prepare the architectural plans, submit the permit package, and schedule every inspection, whether your home is in Seattle, Bellevue, Renton, or Kent.

Is an addition or an ADU the better investment?

It depends on the goal. An addition adds connected living space and usually suits growing families best; a detached ADU adds independent space that commonly rents for $1,800–$3,000+ per month in King County. Blue Lake builds both and can price the two options side by side for your lot.

Serving Bellevue, Seattle, Kirkland, Redmond, Sammamish, Issaquah, Renton, Mercer Island, and communities across King and Snohomish County. Licensed Washington general contractor #BLUELLC760C3.

Looking for whole-home remodeling details in your city?

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