Home additions · Mercer Island, WA
Second-Story Addition in Mercer Island, WA
Build up to add bedrooms and baths while keeping your lot.
Second-Story Addition in Mercer Island, WA
When Mercer Island homeowners search for second-story addition or a dependable home additions contractor near them, they want craftsmanship that lasts and a crew that communicates. That's exactly what we do. Build up to add bedrooms and baths while keeping your lot.
Mercer Island projects often involve sloped lots, shoreline rules, and mid-century homes that benefit from thoughtful structural and design planning.
A home addition lives or dies on the connection to the existing house — foundation, framing, and rooflines have to marry seamlessly so the new space feels original.
What's included in your second-story addition
A typical second-story addition in Mercer Island can involve foundation work, insulation, finishes, windows — and we put the full scope in writing so you know exactly what's covered before work starts.
From room additions and bump-outs to second stories and full primary suites, we handle structural engineering and permits up front so there are no surprises.
How much does a second-story addition cost in Mercer Island?
Most second-story addition projects in Mercer Island fall between $195,000 – $520,000, depending on the size of the space, the finishes you choose, and the condition of what's already there.
Because every home is different, we don't quote final numbers sight unseen. After a free in-home consultation you get a detailed, itemized estimate tied to your actual home additions project — so there are no surprises later.
Why Mercer Island homeowners choose Xion Build
Licensed, bonded, and insured in Washington — every project is built to meet or exceed code and backed by a written warranty.
Honest guidance on where to invest and where to save, so your budget goes toward what adds real, lasting value.
Meticulous job sites and clear daily communication, with respect for your home, your time, and your neighbors.
Our Mercer Island home additions process
We pull the permits, schedule every trade in the right order, and protect your home, landscaping, and daily routine throughout the build.
Handoff includes a detailed walkthrough and a written warranty — not a crew that vanishes the moment the dust settles.
Each phase is inspected and documented, and we keep you updated so you always know what's happening and what's next.
Frequently asked questions
Do you handle permits and inspections?
Yes. We manage permit applications, schedule inspections, and coordinate any required engineering so the work passes cleanly in Mercer Island.
How long does a second-story addition take?
Timelines depend on scope and permitting. Once the plan is confirmed we give you a realistic schedule and keep you updated as the home additions work progresses.
Do you offer a second-story addition in Mercer Island, WA?
Yes. Build up to add bedrooms and baths while keeping your lot. Xion Build is a licensed, bonded, and insured home additions contractor serving Mercer Island and the surrounding WA communities.
Are you a licensed home additions contractor?
Yes — Xion Build is licensed, bonded, and insured in WA. Every project is built to meet or exceed code and is backed by a written warranty.
How much does a second-story addition cost in Mercer Island?
Most second-story addition projects in Mercer Island run $195,000 – $520,000, depending on scope, finishes, and existing conditions. After a free in-home consultation we provide a detailed written estimate so your Mercer Island price reflects the actual project — not a guess.
Related services in Mercer Island
Bump-out addition
Small cantilevered bump-outs to expand kitchens, baths, or dining.
View detailsGreat room addition
A large open living and entertaining space.
View detailsFoundation & footings for additions
Engineered footings and foundations for new square footage.
View detailsHome office addition
A quiet, code-built dedicated workspace with proper electrical.
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