Bathroom Additions in Bellevue, WA

Our team provides permit drawings and full shower waterproofing, delivering usable square footage for homes and code-correct plumbing for both single-story and two-story properties. Backed by a Washington State contractor license and general liability insurance, we take on work at every scale, from a 20 square foot powder room carved out of a hallway closet to a 110 square foot primary en suite on a new footing.

From setback verification and footing excavation to a vent line that actually terminates where the code says it must, our team handles every detail. Serving Bellevue and neighboring Newcastle, Issaquah and Redmond, we deliver disciplined scheduling and reliable, professional, beautiful results on every bathroom addition project.

Call (940) 209-3977 for a free on-site feasibility visit and written estimate. We will tell you what the lot, the code and the drain lines allow before you spend a dollar on drawings.

Where a New Bathroom Can Go

Most Bellevue additions come from one of five places, and they do not cost anything like the same:

Inside the existing footprint. A hallway closet, a corner of an oversized bedroom, dead space under a staircase. Cheapest by a wide margin, with no foundation, roof or envelope work. A half bath and powder room needs only a toilet and a sink, so it fits in surprisingly little floor area.

A bump-out. A small cantilevered or footed extension off the back or side. Real square footage, and it brings foundation, framing, roofing, siding and window work with it.

A garage or bonus-room conversion. Already enclosed and roofed, but usually uninsulated and often on a slab, which changes the drain strategy completely.

An en suite off the primary bedroom. Usually borrowed from a closet or a bump-out, and usually the highest-value addition in a Bellevue house.

Below grade. A basement bath is its own problem, because the fixtures often sit below the main sewer line. That is covered on our basement bathroom remodeling page.

If the walls already exist and the bathroom simply does not work, you want bathroom layout reconfiguration instead. Very different budget.

What a Bathroom Addition Includes

• Feasibility review: setbacks, lot coverage, structure, drain and vent capacity
• Permit drawings and City of Bellevue permit applications
• Foundation, footings and framing where the footprint grows
• Wall and roof framing, roofline tie-in, flashing and siding to match
• Windows, insulation and vapor control
• New drain, vent and supply runs tied into the existing stack
• Electrical: dedicated circuits, GFCI receptacles, IP44 fixtures, exhaust ducted outside
• Waterproofing over the shower walls and floor, then tile
• Fixtures: toilet, sink and wash basin, bathtub or stall shower, towel bars
• Bathroom cabinets, vanity top, mirror, lighting and trim
• Final clean, inspection and walkthrough

Materials and Technical Detail

The shower is the part that has to last. Waterproofing material goes over the shower walls and floor and is then covered with tile, and a new build is the right moment to detail that properly rather than economically. Porcelain is the workhorse for floors and shower walls, glazed ceramic is the value option, and natural stone (marble, onyx, granite, slate) is less uniform in color and pattern so it needs more layout planning. Mosaic earns its price for grip on a sloped floor, encaustic because the pattern runs through the full thickness and does not wear away. Patterns run herringbone, staggered, offset, grid, stacked, pinwheel, basket weave, diagonal and chevron.

We set a pressure-balanced valve so the new shower holds constant pressure with no temperature fluctuation when a fixture runs elsewhere in the house. Showerheads can be fixed, handheld, ceiling-mounted or adjustable spray, and enclosures range from curtains and sliding or folding doors to frameless glass. In a small new bath, a stall shower or a shower and tub combination usually beats a separate tub.

Vanity tops: engineered quartz for consistency, granite or marble for natural variation, solid surface where an integrated sink cuts the seam count, and cultured marble, polyester resin mixed with marble dust and roughly four times stronger than natural granite or marble. Radiant floor heat, as resistive electric mats or hot water tubing, is cheapest to install while the floor is already open.

Related Services

Additions rarely stop at one room. Many clients pair a new bath with a kitchen expansion or addition under one permit set. A new primary suite continues into a master bathroom remodel. Where the goal is a ground-floor suite built for the long term, read accessible and aging-in-place bathroom remodeling. A small addition inside existing space is usually a half bath and powder room build.

The whole bathroom offer sits on our bathroom remodeling page, and the company overview on the home page.

Areas We Serve

Across Bellevue: Lake Hills, Crossroads, Newport, Somerset, Woodridge, Eastgate, Factoria, Bridle Trails, Northeast Bellevue, West Bellevue, Wilburton and BelRed, ZIP codes 98004 through 98009.

Addition work also runs to Issaquah, Redmond, Kirkland, Sammamish and Mercer Island, plus Newcastle, Medina and Clyde Hill. Interstate 405 and Interstate 90 keep it close.