Before choosing a design path
Teardown, addition or major remodel? How to compare the options
Keeping the house can preserve useful work, but it can also leave you paying to work around a building that does not suit your goals. Rebuilding offers more design freedom, but the replacement still has to work under the applicable site and approval rules. Compare both paths before one becomes the default.
On this page9 sections
Define three genuinely comparable options
Write a short must-have brief: rooms, approximate usable space, accessibility, outdoor connections, parking and the parts of the site that matter. Separate essential outcomes from preferences. Then ask the designer to test a limited remodel, a major addition or reconfiguration, and a replacement house against the same brief.
Keep the comparison honest. A kitchen update and a replacement house do not deliver the same result. If the remodel cannot provide the required bedroom arrangement or accessible entry, record that compromise rather than comparing only its lower price. If the new house adds much more area, identify the cost of that larger program separately.
| Option | Potential advantage | Question to resolve early |
|---|---|---|
| Limited remodel | Keeps much of the existing layout and systems | Can it meet the important goals without triggering work you did not budget? |
| Addition or major remodel | May reuse meaningful structure while changing how the home works | Can the retained building support the proposed connections and loads? |
| Replacement house | Lets the design start from a coordinated new building | What can actually be approved and constructed on the cleared site? |
Investigate what is worth retaining
Collect approved plans, later revisions, inspection records and a measured survey. Ask the architect and structural engineer to identify which parts are supported by reliable documents and which need field verification. An old plan is useful evidence, but it is not proof that the building matches it today.
A second story can require investigation of the foundation, load paths and connections. A changed floor plan can affect structural walls and system routes. A daylight basement may depend on grade, moisture and drainage conditions. Ask for a written investigation scope and a statement of the assumptions the concept still relies on.
Discuss exploratory openings, testing and specialist visits before they occur. Obtain owner permission and the required professional assessment. Do not disturb suspect asbestos or lead-containing materials to check conditions yourself. PSCAA has requirements for renovation as well as demolition; have the appropriate professionals establish the safe investigation and work sequence.
- Structure: foundations, bearing locations, lateral system and condition of intended retained elements.
- Systems: condition and capacity of electrical, plumbing, heating, ventilation and service connections.
- Envelope: roof, water entry, insulation and the details where old and new construction meet.
- Site: drainage, access, trees, utilities, easements and the proposed disturbance area.
Find existing plans and permit records → · Puget Sound Clean Air Agency: renovation and demolition requirements ↗ · WA L&I: verify a contractor, tradesperson or business ↗
Do not treat grandfathering as a design strategy
A building that was lawfully established under earlier rules may not meet today's setbacks or another standard. Whether and how it may be changed is a separate question. Ask the city which provisions apply to the proposed scope, whether the existing condition is legally established, and how additions, reconstruction, cumulative work or removal affect the answer.
There is no universal Eastside rule that retaining one wall, a foundation or a percentage of the building preserves every existing right. Local land-use standards, the applicable building or residential code, critical-area provisions and private restrictions can use different tests. A marketing description such as renovation does not decide those tests.
Ask the architect to show a demolition-and-retention plan that matches the actual construction intent. Request the city's interpretation of uncertain conditions before investing in a finished design. If the project depends on a specific exception, compare a compliant alternative and have qualified counsel address any legal reliance or appeal issue.
We are comparing [remodel/addition] and [replacement] at [address]. The attached diagrams show the existing conditions and what each option would retain or remove. Which current provisions apply to the nonconforming elements, reconstruction and any cumulative scope? What documentation or valuation method is required? Which site, tree, critical-area or utility requirements would differ between the two options?
Bellevue Development Services contacts ↗ · Kirkland Development Services Center ↗ · Seattle Existing Building Code and substantial-alteration resources ↗
A remodel is not automatically exempt from site review
Moving a wall inside the house can be a different review problem from adding a floor, enlarging the footprint or rebuilding foundations. Identify the actual structural, system and exterior work. Seattle's addition-and-alteration guidance distinguishes simpler projects from larger or more complicated work and points readers to existing-building requirements. Confirm the code path for the specific building instead of borrowing a rule from another project type.
For an addition or replacement, overlay the complete disturbance area on the site constraints. Tree protection can conflict with excavation outside the final footprint. Drainage may need to be redesigned. A retained driveway can still need review when the project or access changes. Ask whether new service loads affect utilities and fire requirements.
A teardown needs its own preparation, including applicable demolition approvals, hazardous-material requirements, disconnects and site controls. Demolishing the existing home does not establish approval of the replacement. Confirm the sequence before committing to removal.
Seattle addition and alteration permits ↗ · Bellevue permit process and revision instructions ↗ · Puget Sound Clean Air Agency: renovation and demolition requirements ↗ · Compare critical areas and design restrictions →
Compare complete cost and disruption, not just square feet
Ask bidders to show what is assumed sound and reusable. A remodel quote that assumes every hidden condition is acceptable should not be compared with a replacement quote that includes a complete new system. Seek pricing for the most consequential uncertainty or agree how it would be valued if discovered.
Living in the house during work is a planning assumption, not a guaranteed saving. Ask about safe access, utilities, dust control, security and the construction sequence. Price the actual occupied-work approach and the alternative of moving out. Use your own carrying costs rather than a generic monthly figure.
| Category | What to include in the comparison |
|---|---|
| Investigation and design | Surveys, testing, consultants, drawings and alternative studies |
| Approvals and site work | Permits, utilities, drainage, trees, access and required improvements |
| Building work | Demolition or selective removal, retained-element repairs, new construction and finishes |
| Living and logistics | Temporary housing, moves, storage, site security and occupied-work arrangements |
| Schedule and financing | The owner's actual loan, insurance, tax and other time-related costs |
| Uncertainty | Known unpriced scope and a separate reserve for identified risks |
Build a complete site budget → · Compare builder quotes consistently →
A worked example: test the assumption that changes the decision
Illustrative example: a homeowner wants a second story and an open main floor. The first concept assumes the existing foundation and several walls can stay. The alternative is a smaller replacement house designed around current site constraints. Before choosing, the team investigates whether the retained structure supports the addition and asks the city how the proposed scope is classified.
If substantial foundation strengthening and temporary support are needed, the remodel price and construction sequence change. If the replacement cannot achieve an essential site relationship, that option also changes. Neither result means remodeling or rebuilding is always better. The useful finding is which assumption controls this particular decision.
Write a decision checkpoint before final design: proceed with the preferred option if the investigated scope and revised budget remain acceptable; otherwise revisit the alternative. Keep the same functional brief when comparing again.
Keep the approved scope aligned with the work
During construction, unexpected damage may make an intended retained element impractical to keep. Establish in advance who documents that condition, protects the site, obtains a design response and checks the city's revision requirements. Do not simply remove additional structure because the contractor is already mobilized.
Seattle has a revision process for changes to issued permits. Bellevue's process also directs construction-stage design changes back through review. Ask the applicable city whether the proposed change fits a revision, changes the approval path or requires other action. Confirm the answer before affected work proceeds.
Seattle changes to an issued building permit ↗ · Bellevue permit process and revision instructions ↗
Put this guide to work
- Write one functional brief and compare a limited remodel, major remodel or addition, and replacement against it.
- Commission the focused investigation that could change the preferred option. Mark unverified retained conditions clearly.
- Ask the city scope-specific questions using demolition-and-retention diagrams. Check site and private restrictions separately.
- Obtain comparable budgets, schedule assumptions and a written decision checkpoint before committing to final design.
Common questions
Is remodeling always faster to permit?
No. The review path depends on the actual work, site conditions, completeness and applicable rules. A large structural remodel can involve several disciplines and substantial investigation. Compare the local approval paths rather than the labels.
Can I keep the foundation to avoid current zoning rules?
Do not assume so. Ask the city and design team how the proposed work is treated and what evidence supports any existing nonconforming condition. Keeping a foundation does not answer every zoning, building or site requirement.
Should I demolish first so the designer can see the site?
Do not use demolition as a substitute for due diligence. Confirm the replacement concept, approvals, investigation needs and removal sequence first. Qualified professionals can identify appropriate ways to investigate existing conditions.
Written and sources reviewed . This is a comparison framework, not an engineering assessment or legal determination of existing rights. Have the city and your qualified team confirm the applicable rules and the condition of retained work.