Sunroom & Four-Season Room in Mercer Island, WA

Sunroom & Four-Season Room in Mercer Island, WA

Xion Build provides expert sunroom & four-season room in Mercer Island. As a trusted Mercer Island home additions contractor, we manage design, materials, permits, and every trade in-house so your project stays on schedule and on budget. Insulated, conditioned sunrooms usable year-round.

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 sunroom & four-season room

A typical sunroom & four-season room in Mercer Island can involve finishes, foundation work, roofline tie-in, framing — 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 sunroom & four-season room cost in Mercer Island?

Most sunroom & four-season room projects in Mercer Island fall between $145,000 – $423,000, 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

Transparent, written estimates with no hidden fees — you know what you're paying for before work begins.

Meticulous job sites and clear daily communication, with respect for your home, your time, and your neighbors.

Licensed, bonded, and insured in Washington — every project is built to meet or exceed code and backed by a written warranty.

Our Mercer Island home additions process

Design and material selections come next, so finishes, fixtures, and pricing are locked in before demolition — no surprises mid-project.

Each phase is inspected and documented, and we keep you updated so you always know what's happening and what's next.

It starts with a free, no-obligation consultation: what you want, the constraints, and a realistic budget range before you commit to anything.

Frequently asked questions

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