With over a decade of experience, we design and build ADUs and custom home additions that expand your living space, add value, and blend seamlessly with your home’s style.

Renton Home Addition and ADU Construction Specialists

Transform your property with a professional Renton home addition contractor and ADU builder . Our services include custom home additions, extensions, detached and attached ADUs, and energy-efficient upgrades. Over 14 years of experience guarantee top-notch craftsmanship and client satisfaction.
4.9
Based on 36 reviews
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Professional Builder

5 Star Rated Renton Construction Company

14

Years of
Experience

+150

Completed
Projects

FREE QUOTE FOR YOUR ADDITION OR ADU

Professional Addition & ADU Contractor
Seattle’s Eastside, WA

Our Comprehensive Addition & ADU Services Include

ADU Builder in Renton: With over a decade serving Renton homeowners, we bring proven craftsmanship to every Accessory Dwelling Unit project. From solid structural work to precise finishes, our team builds attached and detached ADUs designed for durability, comfort, and lasting value.

Home Additions in Renton: We specialize in high-quality home additions that meet practical needs while upholding our standards for fine construction. Whether you need extra bedrooms, a functional home office, or a dedicated in-law suite, our local knowledge and hands-on approach ensure a result you’ll appreciate for years.

Professional Home Addition Contractor and ADU builder

Let's Talk About Your Remodeling Project

Complimentary Estimate and Expert Guidance from experienced Professionals.

Our ADU and Addition Services

Attached ADUs

Connected to the main house for multi-gen living or rental income. Designed for a seamless tie-in and code compliance.

Detached ADUs

Stand-alone backyard cottages for guests or rental. Built for privacy, durability, and local zoning compliance.

Home Additions

Increase square footage with custom additions that match your home’s style and boost long-term value.

Home Extensions

Targeted expansions: kitchen, bathrooms, living, or sunroom planned for comfort, light, and energy efficiency.

GALLERY

Some Previous Successful Home Extensions Projects in Renton, WA

Why Choose BLC Remodeling LLC for Your Renton Home Additions and ADUs?

Licensed and Insured Renton Contractor

We are fully licensed and insured to perform home additions and ADUs in Renton, ensuring that every project meets state codes and delivers lasting structural integrity.

Knowledge of Renton’s Housing Layouts

Renton’s mix of suburban neighborhoods and hillside properties calls for tailored building approaches. We adapt designs to lot sizes, views, and existing architecture for the best results.

Practical and Comfortable Spaces

Our work includes in-law suites, garage conversions, and expanded living rooms that improve both the usability and comfort of your home.

Durability in Every Detail

We use proven construction techniques, including reinforced framing, moisture protection systems, and premium finishes to ensure your addition stands the test of time.

Over a Decade Serving Renton

Since 2011, we have worked in neighborhoods throughout Renton, delivering results that reflect both local character and high construction standards.
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Schedule an Estimate

Looking for a local Home Extension contractor in Renton? Contact us today to schedule a free consultation, and let us transform your home with our custom remodeling services.

Achieve Your Dream Home With Our Process

Simplified Renton Home Extension Process

1.

Schedule a Consultation

Reach out to us via phone or our contact forms .

2.

In-Home Assessment

We’ll schedule a visit to your home to understand your vision

3.

Receive a Detailed Quote

We’ll provide a detailed quote and project timeline.

4.

Schedule and Begin Work

Once you approve the quote, we'll schedule your project and begin the work.

Start Your Home Transformation Today

Schedule Your Renton ADU or Addition Estimate

Call us anytime, we strive to answer all inquiries within 24 hours.

4.9
Based on 36 reviews
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Yuqiu Wang
04:16 23 Aug 25
We recently completed a full kitchen remodel with BLC remodeling, including new flooring, countertops, and cabinets, and we couldn’t be happier with the result.

The project was actually delivered ahead of the contract schedule, which was a pleasant surprise. They work with licensed plumbers, electricians, and mechanical contractors, and they also handled all the necessary permits. Both the rough-in and final inspections passed on the first attempt.

The team not only did the main remodel but also helped with a lot of small extra tasks around the edges. They were very patient in adjusting cabinet alignments and doing touch-ups until everything looked perfect.

We especially appreciated their clear and timely communication. Any changes we requested were discussed and confirmed right away—for example, after the rough-in, we decided to add a vent hood duct, and they adjusted the plan smoothly without delaying the schedule.

Overall, the workmanship, professionalism, and customer service were excellent. We highly recommend BLC remodeling to anyone looking for a reliable and detail-oriented remodeling company.

Estimate Request Form

Frequently asked questions

For a 1,000 square foot addition in Renton, the cost typically ranges from $75,000 to $190,000. Factors like the addition type, material quality, and local construction costs will influence the final price​

Adding an addition to your existing home is generally more cost-effective than building a new house. Home additions make use of existing infrastructure and utilities, which can significantly reduce costs. However, the total expense will depend on the size and complexity of the addition, as well as the materials used.

The cheapest type of home addition is typically a single-room extension, such as a sunroom or a small bedroom. These additions require less structural work and fewer materials compared to multi-room additions or second-story expansions. Costs can be further minimized by choosing cost-effective materials and designs.

The timeline for home additions varies depending on the project’s scope and complexity. On average, a small addition like a single room can take 3-4 months, while larger projects, such as adding a second story, can take 6-9 months. Detailed planning and efficient project management are crucial to staying on schedule.

Renton’s ADU regulations include:

  • Size: ADUs must not exceed 1,000 sq. ft. or 40% of the principal dwelling’s floor area.
  • Parking: One additional parking space is required.
  • Compliance: Must meet all relevant building codes and zoning regulations.

More details can be found on the Renton City Government website.

Service Areas

Other Service Areas

Don’t see your neighborhood listed? No problem! We are eager to hear about your project. Call us today, and let’s discuss how we can help. Proudly serving homeowners throughout Eastside and Greater Seattle!