Renton WA whole-house remodel and addition: the project workflow

A whole-house remodel with a single-story addition on a Renton rambler or bungalow is a 12–20 month project that runs through Renton CED's Addition/Alteration permit track, an interior gut, a kitchen that drives most of the design, structural wall removals to open the plan, and a WSEC 2021 energy-compliance analysis that decides whether the existing house comes up to current code alongside the new work. Renton's permit track is generally leaner than Seattle's — one building department instead of many reviewers — but the zoning rules, Coal Mine Hazard Area overlay, and PSE utility coordination are Renton-specific. This is the workflow most owners run through, in the order most builders recommend. Click any step on the project map to read the detail. Steps stacked side-by-side run in parallel.

1. Phase 0

   Feasibility

   Five free or near-free checks that take 2–4 weeks and tell you whether the project is real before you spend a dollar on design. Zoning and Coal Mine Hazard Area are the two Renton-specific checks that don't have direct Seattle equivalents.

   2-4 weeks·Free to ~$600 (test kits)·5 steps
   1. 2 in parallel
      0.1Confirm setbacks, lot coverage, and zoning for your lotLook up your lot on the Renton GIS Hub, read your zone designation (R-8, R-10, or R-14), and pull the setback and lot-coverage rules from RMC Title 4 — that tells you whether an addition physically fits before you spend anything on design.Homeowner1-2 days · Free0.2Pull permit history for your addressRun your address through Renton's CASSP portal and the King County Assessor's eReal Property tool to find every prior permit, construction year, and any open issues. Free, takes about 20 minutes, surfaces things that would otherwise blow up the project mid-build.Homeowner20-30 minutes · Free
   2. 2 in parallel
      0.3Decide which scope band you're actually inA 30-minute exercise that picks the right project shape for your budget. Four bands run from a $50K kitchen refresh to a $1M down-to-studs remodel. Knowing which band you're in shapes every decision that follows.Homeowner30-60 minutes · Free0.4Walk the house with an experienced Renton remodel GCGet a GC who has done Renton whole-house remodels to walk through the house for an hour. They'll identify foundation type, knob-and-tube risk, wall-removal feasibility, and Coal Mine Hazard Area implications — 60 minutes of information that would otherwise take four months of design fees.Homeowner, General contractor1-2 hours · Free (most GCs do free walk-throughs to qualify the project)
   3. 0.5Pre-screen the house for lead and asbestosIf the house was built before 1978, federal lead RRP rules apply during construction; before 1980, WA asbestos rules apply. A $300–$600 inspection confirms what you're dealing with so the GC bid can include the right abatement scope.Homeowner1-2 weeks (scheduling + lab turnaround) · $300-$600
2. Phase 1

   Site and existing conditions

   Four documents that describe what you've actually got: a surveyed lot, as-built drawings of the existing house, a structural read on the foundation and addition tie-in, and — for Renton-specific geological conditions — a soils or geotech report if the lot is in or near a Coal Mine Hazard Area or seismic hazard zone.

   4-8 weeks·$3,500-$15,000·4 steps
   1. 2 in parallel
      1.1Order a boundary and topographic surveyHire a licensed land surveyor to set the property corners, shoot the topography, and locate trees and existing improvements. Your designer can't draw setbacks or lot coverage without it.Surveyor2-4 weeks · $1,500-$3,5001.2Measured drawings of the existing houseThe designer measures every wall, window, door, and ceiling height in the existing house. The new design lays on top of these drawings — they have to be accurate to an eighth of an inch.Designer1-2 weeks · $1,500-$4,000 (often included in design fee)
   2. 2 in parallel
      1.3Foundation assessment and addition tie-in evaluationA licensed structural engineer inspects the existing foundation and walks the addition footprint. Two questions: is the foundation OK as-is, and how does the new addition foundation tie into it?Structural eng.2-4 weeks · $1,500-$3,500 (assessment only; full structural design comes later)1.4Order a soils or geotech report if conditions require itRenton properties in Coal Mine Hazard Areas or seismic hazard zones require a geotechnical report before Renton CED will permit foundation work. Many standard Renton lots don't require one — but the check is quick.Geotech eng.3-5 weeks · $2,500-$6,000
3. Phase 2

   Design and engineering

   Engage a designer, develop the program with kitchen-first thinking, work through schematic to permit-ready drawings, design the kitchen specifically, get the structural engineering for wall removals and the tie-in, and run the WSEC 2021 energy-compliance analysis.

   4-7 months·$20,000-$45,000·6 steps
   1. 2.1Engage an architect or designer with Renton whole-house remodel experienceA designer or architect who has finished Renton-area whole-house remodels runs the design phase, coordinates the structural engineer and kitchen designer, and shepherds the Renton CED submittal.Designer, Architect1-3 weeks to hire · Design fee 8-12% of construction cost ($20K-$55K typical)
   2. 2.2Program development with kitchen-first thinkingBefore any drawing happens, work out the program: which rooms, what sizes, what adjacencies. On a whole-house remodel, the kitchen drives most of these decisions — work it out first, then everything else follows.Homeowner, Designer2-4 weeks · Included in design fee
   3. 2 in parallel
      2.3Schematic design through design developmentDesigner takes the program and produces preliminary plans, elevations, and a kitchen study. You iterate. By the end you have a building that fits the lot, fits the budget, and fits the family.Designer, Homeowner8-14 weeks · Included in design fee2.4Kitchen design — work triangle, appliance specs, MEP coordinationThe kitchen gets a dedicated design pass: cabinet layout, work-triangle resolution, appliance specifications, and the MEP coordination that drops out of the appliance schedule.Designer, Homeowner4-8 weeks (overlaps with schematic) · Included in design fee; specialty kitchen-and-bath designer adds $2K-$8K
   4. 2 in parallel
      2.5Structural engineering — wall removals, addition framing, tie-inThe structural engineer designs the addition foundation and framing, the tie-in to the existing, and the beams and posts for every interior wall removal. Stamped drawings and calcs become part of the permit set.Structural eng.5-8 weeks · $4,000-$12,0002.6WSEC 2021 energy compliance analysisYour designer or an energy consultant runs the WSEC 2021 alteration provisions against the proposed scope and determines whether the existing house has to come up to current energy code alongside the new work.Energy consultant, Designer3-5 weeks · $1,000-$4,000
4. Phase 3

   Permits and approvals

   Submit the permit-ready set to Renton CED through the CASSP portal, kick off the sub-permits (including the electrical permit, which Renton issues itself — not WA L&I), handle tree review if regulated trees apply, and respond to correction letters.

   2-5 months·$7,000-$12,000 typical Renton permit fees for $300K-$600K WHR valuation (building permit + 65% plan check + sub-permits)·4 steps
   1. 3.1Submit the Addition/Alteration permit to Renton CEDDesigner uploads the permit set, structural calcs, energy compliance, and survey to Renton's CASSP portal. Renton CED triages, charges fees, and assigns the application to reviewers.Designer, Homeowner2-3 weeks to intake; plan review timing varies (confirm with Renton CED at application) · Building permit + 65% plan check ≈ $5,500-$9,500 for $300K-$600K project valuation (2025 schedule)
   2. 3.2Pull electrical, plumbing, and mechanical sub-permitsThe GC pulls sub-permits for electrical, plumbing, and mechanical work — all through Renton CED. Important: Renton issues its own electrical permits; WA State L&I does not issue or inspect electrical work in Renton.Electrician, Plumber, HVAC contractor, General contractorRun in parallel with main permit; each issues in 1-3 weeks · Residential base fees (2025): electrical $277+ (200A new service), mechanical $67+, plumbing $67+ — itemized add-ons + 40% plan check each
   3. 3.3Tree review (RMC 4-4-130) if regulated trees applyRenton's tree retention regulations apply when construction activity would affect a significant tree (6-inch DBH) or landmark tree (24-inch DBH) on or adjacent to your lot.Homeowner, Arborist2-4 weeks · Included in permit process; arborist report $400-$1,200 if required
   4. 3.4Respond to Renton CED correction lettersYour designer turns Renton CED's review comments into revised drawings and a response letter. Renton's process is generally leaner than Seattle's, but expect 1–2 correction cycles on a project this size.Designer, Homeowner3-5 weeks per cycle; 1-2 cycles typical · Included in design fee
5. Phase 4

   Bid and contract

   Send the permit-ready set to three to five GCs who match your scope band. Verify them against WA L&I, decide on phasing, negotiate the contract, and sign it.

   6-10 weeks·$2,000-$8,000 (insurance + attorney + temporary housing setup)·4 steps
   1. 4.1Solicit bids from 3-5 Renton whole-house remodel GCsSend your permit-ready plans to three to five GCs who match your scope band, and ask them all to bid the same scope so you can compare apples to apples.Homeowner, General contractor3-4 weeks · Free
   2. 4.2Verify GC license, bond, insurance, and remodel historyPull L&I status (active, bonded, insured), check recent Renton remodel permits, confirm EPA RRP certification if the house is pre-1978. About 30 minutes plus a site visit.Homeowner1-2 days · Free
   3. 4.3Negotiate and sign the GC contractFixed-price is what most owners want. Cost-plus only works with a guaranteed maximum price (GMP) cap. On contracts over $300K, an attorney review pays for itself.Homeowner, General contractor, Attorney1-2 weeks · $1,000-$4,000 if attorney-reviewed
   4. 4.4Decide phasing strategy and where the family livesMost whole-house remodels finish faster and cost less if done all at once with the family moved out. Some owners phase to stay in the house longer. Both work; pick deliberately.Homeowner, General contractor, Insurance1-2 weeks · Decision is free; consequences run $15K-$60K
6. Phase 5

   Build

   Six to twelve months of construction: abatement first, then addition foundation and shell, then interior demo and framing, then MEP rough (with PSE for service, not SCL), then insulation and drywall, then the kitchen and finishes, then the inspection sequence that gets you to Certificate of Occupancy.

   6-12 months·Built into the GC contract; allowance lines true up against actual·8 steps
   1. 5.1Lead and asbestos abatementBefore any meaningful demo, the asbestos abatement contractor and RRP-certified GC handle the regulated materials. One to three weeks; produces PSCAA clearance and RRP documentation.General contractor1-3 weeks · $5,000-$25,000 (varies with how much asbestos and lead is present)
   2. 5.2Addition foundation, tie-in, and shellThe new addition gets its foundation poured, the tie-in to the existing foundation is detailed and inspected, and the addition framing goes up. Renton CED conducts required inspections at footing and framing stages.General contractor, Structural eng.4-8 weeks · Built into GC contract
   3. 5.3Interior demo and structural framing (wall removals + new framing)The existing house gets opened up to the level the scope requires, interior bearing walls come out and beams go in, and the addition's interior framing ties in. The most disruptive phase.General contractor, Structural eng.6-12 weeks · Built into GC contract
   4. 5.4MEP rough-in + service upgrade (PSE)Electrical, plumbing, and mechanical roughs go in the open framing. PSE upgrades the electric service if needed. Each trade gets a separate inspection before drywall.Electrician, Plumber, HVAC contractor5-9 weeks · Built into GC contract; PSE service upgrade fee varies
   5. 5.5Insulation, drywall, paint, and rough finishesWalls and ceilings get insulated (to WSEC 2021 CZ4C values), drywalled, taped, primed, painted. Trim goes on. Floors go down. Stage one of the finish phase.General contractor6-10 weeks · Built into GC contract
   6. 5.6Kitchen install + bathroom finishes + appliance setCabinets, counters, tile, fixtures, and appliances. The longest finish phase because of cabinet and counter lead times. Start ordering at end of framing.General contractor6-10 weeks · Built into GC contract; allowances true up against actual
   7. 2 in parallel
      5.7Final tests and inspections (energy, blower-door, mechanical)Code-required tests and inspections before final occupancy: blower-door air leakage test, duct leakage test, final mechanical, final plumbing, final electrical, final building.General contractor, Energy consultant1-2 weeks · Built into GC contract; testing fees $400-$1,0005.8Sewer and utility connections (Renton Public Works / Soos Creek WSD)If the addition adds square footage, confirm the existing sewer connection can handle the new load and that no utility permit is needed from Renton Public Works or the applicable district.General contractor, Homeowner1-3 weeks to confirm; utility work varies · Included in GC contract if in scope; utility connection fees vary
7. Phase 6

   Final inspection, move back in, and home record

   Certificate of Occupancy issues from Renton CED, the family moves back in, the warranty walk happens, and the completed remodel becomes part of the permanent home record.

   3-6 weeks·Move-back logistics + minor punch-list items·3 steps
   1. 6.1Final building inspection and Certificate of OccupancyRenton CED's building inspector signs off and issues the Certificate of Occupancy — your legal signal to move back in.Homeowner, General contractor1-2 weeks · Included in permit fees
   2. 6.2Move back in and conduct warranty walkFamily moves back in, the GC hands over the project, and you conduct a formal warranty walk to document punch-list items and establish the warranty clock.Homeowner, General contractor2-4 weeks · Minor punch-list items (typically $1,000-$5,000 GC cost)
   3. 6.3Update the permanent home recordThe completed remodel — drawings, permits, warranties, appliance data — goes into the permanent home record. This is the foundation that makes future work, insurance claims, and eventual sale easier.Homeowner1-2 days · Free