Home Additions in South Seattle
Design-build home additions for South Seattle homes — 25 to 30 minutes north of our Milton headquarters. We work throughout Beacon Hill, Columbia City, Seward Park and the rest of South Seattle.
Home Additions in King County
Your additions project, built for South Seattle homes
Good additions work starts with the homes it happens in — and after five generations across the South Sound, we know South Seattle's.
South Seattle's housing spans landmarked Craftsman rows in Columbia City, stately Tudors and brick homes around Seward Park, early-1900s boxes and bungalows on Beacon Hill, and postwar homes toward Rainier Beach.
We take on a lot of thoughtful old-house work in South Seattle, where a Columbia City Craftsman or Seward Park Tudor deserves a remodel that respects its bones while bringing systems and layouts up to modern life. Permits go through Seattle DCI, and projects in the Columbia City landmark district get extra design review that we plan for from day one. Basement apartment and DADU conversions are big here too, since Seattle zoning encourages them and lots along the Rainier Valley often have alley access.
- Permits handled with King County
- In-house 3D design before we build
- Licensed, bonded & insured — WA #HOMERDB750MH
- Financing assistance for South Seattle homeowners
Additions projects across South Seattle
Neighborhoods we regularly work in:
- Beacon Hill
- Columbia City
- Seward Park
- Hillman City
- Rainier Beach
- Brighton
- Georgetown
ZIP 98108, 98118, 98178 · King County
Home Additions nearby
Why homeowners choose us
Home Additions the design-build way
When your family has outgrown the house but not the neighborhood, an addition lets you stay rooted in South Seattle while gaining the space you actually need — a primary suite, a bigger kitchen and family room, a main-floor bedroom for aging parents, or a full second story. Home Renovation Design & Build designs and constructs additions as one integrated team: our in-house designers model the expanded home in 3D, inside and out, so you can see exactly how the new space connects, how the roofline resolves, and how the addition looks from the street.
Additions are the most technically demanding residential projects — foundations tied to existing footings, roof structures married cleanly, floor levels matched to the quarter inch, and setback and lot-coverage rules navigated with your King County jurisdiction. This is fifth-generation builder territory. We manage the structural engineering, pull every permit, and sequence construction to keep your existing home weathertight and livable throughout. Fully licensed and insured (WA license HOMERDB750MH), we build additions that look and feel original to the house.
Seamless integration, inside and out
Matched siding, rooflines, window styles, floor heights, and trim profiles — a well-built addition should make visitors ask which part is new.
Engineering handled end to end
Foundation design, beam sizing, and structural connections to the existing house are engineered, permitted, and inspected — never improvised.
Your home stays livable
We build the shell from the outside and delay breaking through to the existing house until late in the schedule, keeping your family weathertight and functional.
Zoning and setbacks navigated for you
Lot coverage, height limits, setbacks, and critical-area rules vary by jurisdiction — we confirm what's buildable on your lot before you invest in design.
Fixed-price certainty on a big investment
Complete scope, engineered plans, and firm pricing before ground breaks, so a major addition doesn't come with major financial suspense.
Warranty-backed structural work
Our written workmanship warranty covers the addition from foundation to finishes.
The process
How your South Seattle project unfolds
Feasibility & consultation
We assess your lot's setbacks, coverage limits, and structural realities, then align the addition concept with your space needs and budget.
Design, engineering & 3D preview
Floor plans, exterior elevations, and structural engineering come together with 3D renderings of your expanded home — and a fixed-price proposal.
Permit approval
We submit the full permit set to your jurisdiction and handle plan review comments, utility considerations, and inspection scheduling.
Foundation to finish
Excavation, foundation, framing, roof tie-in, mechanical rough-ins, and finishes — with the connection to your existing home opened as late as possible.
Blending, walkthrough & warranty
We finish the transition spaces so old and new flow together, walk the completed addition with you, and deliver our written warranty.
Investment
What additions projects cost
Home additions in the Puget Sound area typically represent an investment of $150,000–$300,000 for single-story additions like primary suites or family rooms, and $300,000–$500,000+ for large or second-story additions — driven by size, foundation work, and finish level. Your consultation and estimate are free, and financing options can make a major addition manageable.
Financing assistance available
We help South Seattle homeowners find financing that fits their project and budget — ask about options during your free consultation.
Get My Free EstimateFAQs
Home Additions questions in South Seattle
How long does a home addition take to build?
Most additions take 3–6 months of construction, with second-story additions at the longer end. Design, engineering, and permitting typically add 3–5 months up front — jurisdiction review times in the South Seattle area vary, and we manage that process for you.
Can I add on to my house, or will zoning stop me?
It depends on your lot's setbacks, coverage limits, and height allowances. We research your parcel's zoning during the free feasibility consultation, before you spend anything on design — so you know what's possible on day one.
How much does an addition cost in South Seattle?
Most single-story additions run $150,000–$300,000 and second stories $300,000–$500,000+, depending on size and complexity. After design and engineering you receive a fixed-price contract, so the budget is locked before excavation begins.
Do we have to move out during construction?
Almost never. We build the addition as a sealed shell from outside and cut through to the existing house only when the new space is nearly finished, so your home stays secure, weathertight, and livable for nearly the entire project.
Will the addition match our existing house?
That's the standard we build to. We match or complement siding, roofing, windows, and interior finishes, and our 3D renderings show you exactly how the combined home will look before construction — all backed by our written workmanship warranty and WA license HOMERDB750MH.
Free consultation
Start your South Seattle additions project
Tell us about your project and we'll reply within one business day — serving Beacon Hill, Columbia City, Seward Park and all of South Seattle, with zero obligation.