Remodeling an existing house in Seattle, Bellevue and Kirkland
Remodeling design at DeZZign is the project for a house or building that already stands and keeps most of its envelope: the same foundation, outer walls and roof, with a new plan, new systems and new finishes inside. We work on whole houses and single floors, character homes and plainer post-war houses in Seattle, Bellevue and Kirkland. The order of work sets this service apart from a new house: first we learn what the building is made of and what state it is in, then decide what stays, and only then draw the new rooms.
A project from our portfolio shows that order on a small scale. The Minimalist style apartment (116 m², historic center of Kharkiv, 2021) had three months for design and realization together. Work began with the demolition of floors, walls and windows, yet the kitchen left by the previous owner stayed: we replaced its appliances and fronts, rethought its design and added a backsplash. In the wardrobe we kept the mechanisms and valuable hardware and replaced only the particleboard. Keeping sound parts is a design decision, and it depends on knowing which parts are sound.
Before the first sketch: measured survey and condition assessment
Original drawings of an older house, when they exist at all, show what was planned decades ago. They rarely show the wall someone removed in the 1970s, the bathroom added over the garage or the joists notched for a drain. So the project begins with our own record of the building:
- measured plans of every floor, with ceiling heights, wall thicknesses, openings, the stair and the routes of ducts, drains and chimneys;
- a photo survey of each room, the attic, the crawlspace or basement and the exterior;
- the framing: joist sizes, spans and direction, posts and beams, and which walls carry load from above;
- moisture: stains, soft wood at sills and around old leaks, the state of the crawlspace vapor barrier, downspouts that empty against the foundation;
- the systems: electrical panel and wiring type, supply and drain pipe materials, heating equipment and its fuel.
Some answers sit behind finishes, so we agree on small inspection openings in places that will be rebuilt anyway, and the structural engineer we work with reads the same findings. A Puget Sound Clean Air Agency notice of September 2023 states that before any renovation, regardless of the age of the structure, an asbestos survey must exist or be done by an AHERA-certified building inspector; owners of single-family homes they live in may survey for their own renovation. Removal comes after a notification to the agency and is done by a certified asbestos contractor. Planning around a ceiling texture that tests positive costs far less before design than after demolition.
Our drawing sets also say plainly that dimensions taken over existing finishes are checked again after demolition. The notes of the Minimalist style set, analysed sheet by sheet in 68 Sheets: What an Interior Design Project Actually Includes, carry that line, because old plaster can hide a wall that is an inch or more out of plumb.
What to keep and what to replace in an old house
Every element of an existing house gets one of three verdicts: keep as is, repair, or replace. We make that call with a few rules that have little to do with taste:
- anything that will be hidden behind new finishes and is near the end of its life is replaced now, since changing old supply pipes during demolition costs a fraction of opening a new tiled wall later;
- sound structure stays, even where the new plan would be easier without it; moving a bearing wall is possible, but it should buy something the family will feel every day;
- elements that give an older house its character, such as original trim, a staircase, solid wood floors or old wood windows, are assessed for repair before anyone prices a replacement;
- built-in furniture with good carcasses and hardware can take new fronts and a new layout, as the kitchen and wardrobe in our Kharkiv apartment did;
- windows are decided together with the energy plan, because a replacement unit must meet the current energy code, while a repaired original with interior storm panels keeps the look of a character facade.
The outcome is a keep-and-replace plan drawn over the measured plans in three colors. Contractors price from it, and you see where the money goes before any finish is chosen.
Removing walls, new openings and a new stair
Remodels that change how a house lives often touch structure: a wider opening between kitchen and living room, a removed wall, a moved stair, a bathroom upstairs where the floor was never meant to carry a stone tub. Each sends load along a new path. A beam replaces the wall, posts take the ends of the beam, and the posts need something solid under them, often a new footing in the crawlspace.
SDCI Tip 316, updated October 29, 2026, allows interior alterations of single-family homes and duplexes to use the faster subject-to-field-inspection (STFI) permit when new beams or headers in load-bearing walls stay within set spans without an engineer's stamp: up to 8 feet when they support no more than two stories above plus the roof, and up to 14 feet with one story above plus the roof. Longer spans, point loads landing on old joists and anything touching the foundation go to the structural engineer, and the calculations become part of the drawings.
A new stair is a structural change even when it looks like carpentry. The opening cuts joists, and their cut ends hang on doubled framing that carries the load to the walls. The stair also needs headroom over every step, which in a low attic or basement decides where it can go; our article What Kind of Staircase Is Right for Your House? shows the main types. An old floor can also be strong enough and still too springy: large porcelain slabs and stone crack where joists deflect, so the floor under a new bathroom may need stiffening.
When a whole-house remodel becomes a substantial alteration in Seattle
Seattle draws a line that every owner planning a deep remodel should know before the scope is fixed. According to SDCI Tip 316, if you are reconfiguring spaces or replacing wall surfaces in more than 60 percent of the existing house, the project is likely a substantial alteration. Such projects require certain upgrades throughout the structure, including rooms where nothing else changes (section R107.5.1 of the Seattle Residential Code), and the plans must show which rooms get new drywall or plaster.
To use an STFI permit for a substantial alteration, SDCI asks for one of three things: structural plans stamped by a civil or structural engineer showing seismic upgrades to the foundations and cripple walls (the short walls between the concrete foundation and the first floor), approved Earthquake Home Retrofit plans for the connection between the framing and the foundation, or proof that the house was built under the 1985 Uniform Building Code or a later one. For the Earthquake Home Retrofit permit the city publishes a prescriptive plan set: anchor the house to its foundation, brace the cripple walls, connect them to the floor framing. Houses outside that set need an engineered design.
SDCI's "Do You Need a Permit?" page says that minor repairs or alterations costing $6,000 or less in any six-month period need no permit, while work on load-bearing supports, changes to the building envelope and work that reduces egress, light, ventilation or fire resistance need one no matter how small. Bellevue and Kirkland run their own permit departments, so for each address we check the current rules on the project date and shape the scope around these thresholds instead of meeting them at intake.
Replacing wiring, plumbing and heating in an older house
Open walls are the cheapest moment to renew what runs inside them. Knob-and-tube or early cloth-insulated wiring has no ground, and knob-and-tube was designed to shed heat into open air, so a wall cannot be insulated around it while it is live. A heat pump, an induction range and a car charger together may need more than an old panel and service can supply, and a service upgrade has its own lead time with the utility.
Galvanized steel supply pipes corrode from the inside, which narrows them and lowers the pressure on upper floors. Cast-iron drains corrode and crack after decades in service. We replace both while walls are open, and check the fall of new drains against the joists before a new bathroom position is final.
Replacing an oil or gas furnace with a heat pump changes the ductwork. The unit should be sized after the insulation and window decisions, because an oversized one runs in short bursts, wears faster and controls humidity poorly in summer. SDCI's single-family addition and alteration checklist lists a heating equipment sizing calculation and the energy code compliance path among the submittals, so these numbers belong in the permit set from the start.
Energy upgrade of an older house: insulation, windows and air
Washington's residential energy code treats a remodel by its parts. Section R503 of WAC 51-11R requires altered work to meet the code for new construction without requiring the unaltered portions of the house to comply. For the envelope it has a practical exception: ceiling, wall or floor cavities exposed during construction may simply be filled with insulation, with 2x4 framed walls insulated to at least R-15. A replacement window or door has to meet the U-factor and SHGC values of the code table, and SDCI Tip 316 repeats that new windows must meet the Seattle Energy Code prescriptive requirements.
The code sets the minimum; the design decides how far above it to go and in what order. Air sealing comes first, because warm indoor air leaking into a cold wall carries moisture with it. Insulation follows, then windows set so that their frames line up with the insulated layer, and only then the heating system, sized for the house the upgrade leaves behind. Once a house is sealed, moisture from cooking, showers and breathing needs a planned way out, which means continuous mechanical ventilation, preferably with heat recovery.
Exterior insulation is the most effective upgrade for walls, but it changes window reveals, eaves and trim, so on a house with a valued street front it becomes a facade decision. Our article Let's Talk About Insulating a Private House explains where heat leaves a house. A certified standard, if you want one, is settled before the scope is fixed, since it changes wall and window details from the first drawing.
Living at home during the remodel, or moving out
Whether you stay in the house shapes the plan as much as the budget does, so we settle it at the concept stage. A remodel done in phases keeps one bathroom, a working kitchen corner and heat in part of the house while the crew works behind dust barriers in the rest. It takes longer and costs more in protection, but saves rent. Moving out completely lets the contractor open everything at once, which shortens the job and brings the hidden problems to light together, while they are still cheapest to solve.
Some weeks are hard to live through in any plan: asbestos abatement, floor sanding and finishing, the days when water or power are off for system changeovers, and drywall sanding. We mark them on the schedule so you can be away for those stretches only. Seattle's rain also has a say. Work that opens the roof or removes windows is better placed in the drier months, and long-lead items such as windows, a heat pump or custom millwork are ordered from the approved drawings early, so that a late delivery does not leave a wall open into the wet season.
Owners who live elsewhere follow the work through our site visits and reports during supervision. After demolition we also re-measure and adjust the dimensions that depended on the old finishes, before cabinets and stone are ordered to size.
What the remodeling drawing set contains, and who signs what
A remodel set differs from a new-house set mainly in its first sheets. Before the new plans come the existing-conditions drawings and a demolition plan that shows, wall by wall, what is removed, kept or protected. Then follow dimensioned floor plans, ceiling plans, electrical and plumbing layouts, sections, interior elevations, tile and millwork drawings and schedules. The structural engineer adds beam, post and footing details and the seismic work where the project needs it, and the energy code compliance path is written on the plans.
For scale, the interior set of our Minimalist style apartment ran to 68 A3 sheets, 24 of them renderings and the rest drawings that trades build from. Whole houses add structural and envelope sheets.
Roles stay clear. Our architects develop the documentation to local codes; drawings that require a local license are signed by licensed professionals we work with. The contractor builds from the approved set, and we work with your own contractor or one chosen after bidding.
Fees, budget and the reserve for what the walls hide
Our fee for remodeling design is discussed individually, and so are the design time and supervision. As our price answer says, for a kitchen or bathroom remodel fees typically start from $3,000-5,000, and whole-home renovations are priced individually after the first consultation and a site review. The number moves with the floor area, the amount of structure that changes, the substantial alteration line, the systems replaced, the depth of the energy upgrade and the site visits in supervision.
Construction budgets for existing houses need a reserve that a new build can do without, because some facts appear only when the finishes come off. We size it from the survey rather than from a rule of thumb: every open question on the keep-and-replace plan, such as rot under a tub, an undersized beam or an unrecorded drain, gets a likely cost. Inspection openings before design shorten that list. We also agree in advance which wishes are cut first if the reserve runs out.
Mistakes that make a remodel cost twice
- Choosing finishes before the survey, then redrawing the bathroom when the joists under it turn out to need replacing.
- Removing a wall on the contractor's eye, without checking whether it carries the floor above or a point load from the roof.
- Insulating walls that still hold live knob-and-tube wiring, or sealing a house tight without planning ventilation.
- Replacing windows one year and the siding the next, which means two rounds of flashing work at the same openings.
- Leaving original pipes behind new tile because they still seem to work.
When remodeling design fits, and when another service fits better
This service fits when the building stays and its inside changes deeply: a new layout across floors, structure, systems and an energy upgrade together. If you need more space than the envelope holds, our home additions page covers building out and up. A new layout in a condo, or a plan change without major system work, belongs to floor plan redevelopment, which also covers lead paint in older Seattle homes. Turning offices into homes needs its own feasibility study, described under office to residential conversion. When the old house is not worth keeping, start from house plans for a new one. A new outside skin is facade design, and a certified energy target is Passive House and sustainable design. For finishes and furniture alone, with no structural or system work, interior design is the simpler start.
