Home Additions for Seattle & the Eastside

Most home additions in Seattle and the Eastside start around $150,000. Costs typically range between $500 and $700 per square foot, depending on the complexity, design, and finishes selected. At Emerald City Construction, we provide detailed and transparent estimates so you can plan your budget with confidence.

A second-story addition is one of the more significant investments because it requires extensive structural work. These projects usually fall on the higher end of the $500–$700 per square foot range. In comparison, single-story extensions, sunrooms, or bump-outs often require less engineering and may be closer to the lower end of that spectrum.

The overall cost is shaped by size, structural requirements, finishes, and design complexity. Premium materials, custom millwork, or spa-like bathrooms will elevate costs, while simpler layouts and standard finishes may reduce them. Labor availability in Seattle, current material prices, and permit requirements also play an important role.

Yes. Every home addition requires permitting through local jurisdictions, and costs can vary. For Seattle and surrounding areas, permit fees typically range from $35,000 to $60,000, plus an additional $10,000–$20,000 in impact and utility connection fees. Our team manages this process for you, ensuring compliance and helping you avoid costly delays.

Timelines vary depending on scope and complexity. Smaller bump-outs or sunroom additions may take three to six months, while a larger second-story or multi-room addition could extend to nine months or more. We carefully sequences design, permitting, and construction to keep projects moving smoothly and on schedule.

Yes. A well-executed addition not only provides extra space but also enhances comfort and property value. In high-demand markets like Bellevue, Mercer Island, Kirkland, and Seattle, the return on investment can be significant, especially when the addition includes a new primary suite, kitchen expansion, or dedicated living space.

Not always. Smaller additions or projects limited to one section of the home may allow you to stay comfortably in place. For larger projects, such as second-story builds, many clients choose temporary housing or storage solutions to minimize disruption. We’ll help you evaluate the best approach for your family’s comfort and convenience.

Our design-build team specializes in creating additions that look original to your home. From matching exterior details and rooflines to carrying finishes and materials throughout, we ensure every addition feels cohesive. Our goal is to enhance both function and aesthetics so your home feels elevated, not pieced together.

Yes. Emerald City Construction is a full-service design-build firm. That means our in-house designers and builders work together from the very beginning to bring your vision to life. This integrated approach streamlines communication, reduces unexpected costs, and results in a beautifully cohesive final product.