Home Additions in Federal Way
Design-build home additions for Federal Way homes — about 10 minutes north of our Milton headquarters. We work throughout Twin Lakes, Dash Point, Marine Hills and the rest of Federal Way.
Home Additions in King County
Your additions project, built for Federal Way homes
Good additions work starts with the homes it happens in — and after five generations across the South Sound, we know Federal Way's.
Federal Way boomed in the 1960s through 1980s, so the typical house is a rambler, split-level, or tri-level from that era, with Puget Sound view homes in Marine Hills and Dash Point and golf-course homes around Twin Lakes.
Federal Way is ten minutes up the hill from our shop, and its huge inventory of 1960s-80s homes keeps us busy with kitchen wall removals, primary suite conversions, and whole-interior refreshes. Permits are handled by the City of Federal Way's community development department, which we work with constantly. In Marine Hills and Dash Point, remodels often revolve around capturing the Sound view, so we do a lot of window enlargements, deck rebuilds, and main-floor reconfigurations there.
- Permits handled with King County
- In-house 3D design before we build
- Licensed, bonded & insured — WA #HOMERDB750MH
- Financing assistance for Federal Way homeowners
Additions projects across Federal Way
Neighborhoods we regularly work in:
- Twin Lakes
- Dash Point
- Marine Hills
- Steel Lake
- Mirror Lake
- West Campus
- Lakota
ZIP 98003, 98023 · 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 Federal Way 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 Federal Way 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 Federal Way homeowners find financing that fits their project and budget — ask about options during your free consultation.
Get My Free EstimateFAQs
Home Additions questions in Federal Way
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 Federal Way 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 Federal Way?
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 Federal Way additions project
Tell us about your project and we'll reply within one business day — serving Twin Lakes, Dash Point, Marine Hills and all of Federal Way, with zero obligation.