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.
Mercer Island Home Addition and ADU Building Contractors
Professional Builder
- Licensed & Insured Local Contractor
- Expertise in Permits & Zoning
- Fixtures, Materials & Labor Included
- Custom Home Addition & ADU, DADU Solutions
- Quality Materials & Sustainable Practices
- Reliable, Experienced Craftsmanship
- Full Design & Project Planning
5 Star Rated Mercer Island 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 Mercer Island: With over a decade serving Mercer Island 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 Mercer Island: 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.
- Garage Conversions
- Sunrooms
- In-law Suites
- Guest Suites
- Home Offices
- Basement Conversions
- Second Story Additions
- Kitchen Extensions
- Bathroom Additions
- Detached ADUs
- Attached ADUs
- Energy-Efficient Upgrades
Let's Talk About Your Remodeling Project
Complimentary Estimate and Expert Guidance from experienced Professionals.
Other Services in your Area
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.
- Directly attached to home
- Shared Wall Structures
- Integrated Utilities
- Space-Efficient Layouts
Detached ADUs
Stand-alone backyard cottages for guests or rental. Built for privacy, durability, and local zoning compliance.
- Stand-Alone Structures
- Private Entrances
- Independent Utilities
- Flexible Use Options
Home Additions
Increase square footage with custom additions that match your home’s style and boost long-term value.
- New Bedrooms
- Home Offices
- In-Law Suites
- Seamless Integration
Home Extensions
Targeted expansions: kitchen, bathrooms, living, or sunroom planned for comfort, light, and energy efficiency.
- Enlarged Kitchens
- Spacious Living Rooms
- Added Sunrooms
- Seamless Integration
Why Choose BLC Remodeling LLC for Your Mercer Island Home Additions and ADUs?
Licensed and Insured Mercer Island Contractor
We are fully licensed and insured for construction on Mercer Island, ensuring every home addition or ADU meets state and local building standards. Our focus is on safe, precise construction with lasting value.Familiar with Mercer Island’s Unique Building Landscape
Mercer Island properties often have specific waterfront regulations, slope considerations, and high-end design requirements. We address these factors early to keep your project moving smoothly.Tailored Additions for Island Homes
Our projects range from second-story expansions to detached guest houses that complement the island’s mix of modern and traditional architecture. Each design is customized for function, comfort, and aesthetic value.High-Quality Craftsmanship and Materials
We use moisture-resistant construction techniques, premium finishes, and detailed carpentry to ensure every project withstands the local climate while maintaining a refined appearance.Building on Mercer Island Since 2011
Over the past decade, we have delivered home additions and ADUs throughout Mercer Island, creating spaces that align with both homeowner vision and community standards.
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Achieve Your Dream Home With Our Process
Simplified Mercer Island Home Extension Process
1.
Schedule a Consultation
2.
In-Home Assessment
3.
Receive a Detailed Quote
4.
Schedule and Begin Work
Start Your Home Transformation Today
Schedule Your Mercer Island ADU or Addition Estimate
Call us anytime, we strive to answer all inquiries within 24 hours.
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.
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Frequently asked questions
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.
On Mercer Island, ADUs must meet specific criteria:
- Size: Maximum of 1,000 sq. ft. or 40% of the primary dwelling’s floor area.
- Parking: One additional parking space required for the ADU.
- Compliance: Must adhere to all relevant construction codes.
For more details, visit the Mercer Island 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!