“Home Addition Architect in Redmond, WA

*By David Meade, AIA, NCARB | Piper Cole Architects*

> TL;DR: Home additions in Redmond, WA are governed by NR zone rules that changed in January 2025 (Ordinance 3186) and again in June 2025 (Ordinance 3220). Permit review typically runs 60 days for standard residential additions. Construction costs run $600–$800/sq ft for permitted additions in the current Eastside market. If you’re planning a second story, rear addition, or ADU in Redmond, the site-specific zoning math matters before you talk to a contractor.

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Why Redmond Addition Projects Require Early Zoning Review

Redmond’s residential zones changed meaningfully in 2025. Ordinance 3186 (effective January 1, 2025) updated setback requirements, lot coverage maximums, and FAR limits for the NR (Neighborhood Residential) zone. Ordinance 3220, adopted June 17, 2025, further refined development standards in response to the state’s HB 1110 middle-housing mandate.

For homeowners planning a home addition, these changes matter in two ways:

First, your lot may have more buildable envelope than it did under the 2024 code — particularly if your property is in a zone that gained reduced setbacks or increased lot coverage allowance.

Second, additions that cross certain thresholds (floor area, height, or proximity to critical areas) now trigger Redmond’s enhanced design review process, which adds timeline and documentation requirements.

The clearest first step for any Redmond addition project is a pre-application meeting with the City of Redmond Development Services. These are free, available by appointment at 425-556-2478, and typically produce a one-page letter documenting applicable setbacks, lot coverage limits, and special conditions — the document that should inform your architect’s site analysis and design footprint before a single drawing is made.

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Redmond NR Zone Development Standards: The Numbers That Shape Your Addition

The following parameters apply to standard residential lots in Redmond’s NR zone as of July 2025. Individual lot conditions (easements, critical areas, existing structures) can modify these — confirm with Development Services before committing to a design.

Parameter	NR Zone Standard (2025)
Front setback	20 ft (some lots 15 ft with pre-application confirmation)
Side setback (standard)	5 ft
Rear setback	20 ft
Maximum lot coverage	45% (lot area covered by structures)
Maximum FAR (floor area ratio)	0.5 in most NR sub-zones
Maximum building height	30 ft
Permit submission portal	MyBuildingPermit.com
Standard residential review	5–28 business days
Expedited review available	Yes — contact permits@redmond.gov

The lot coverage and FAR limits are often the binding constraints. A 7,000 sq ft Redmond lot at 45% coverage allows 3,150 sq ft of total structure footprint. If your existing house covers 2,000 sq ft, you have 1,150 sq ft of available lot coverage for an addition — but only if FAR and setbacks don’t eliminate that before coverage does.

I run this math as the first step in any Redmond addition feasibility review. The envelope is often smaller than homeowners expect, and it shapes every design decision that follows.

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Second Story vs. Rear Addition: The Redmond Decision Framework

Most Redmond homeowners planning an addition face a version of the same choice: build up (second story) or build out (rear addition). Neither is automatically better. The decision depends on your lot, your existing structure, and your goals.

Second story addition: when it makes sense

• Your lot is coverage-constrained — you have hit or are near the 45% lot coverage maximum, leaving no room for a rear or side addition
• You want to maximize finished square footage relative to permit scope (a second story roughly doubles usable space without increasing footprint)
• The existing roof is at end of life or needs replacement regardless — adding a story while the roof is off reduces the premium
• You want to preserve backyard space for outdoor use or a future ADU

Second story addition: what to watch for

• Existing first-floor framing must support the second-story load. Redmond requires structural engineering documentation for any second story addition. Older homes (pre-1990) often need beam and header upgrades
• Interior disruption is significant — the first floor becomes a construction zone for months
• Cost per square foot is typically higher than a rear addition at similar finish level, because structural work dominates early phases

Rear addition: when it makes sense

• You have available lot coverage (away from the 45% cap) and rear setback clearance
• You want to expand a ground-floor living area — kitchen, family room, primary suite — without the cost of structural load-path modifications
• You have a single-story home and want to stay single-story
• Timeline pressure: rear additions typically permit faster than second stories because structural documentation is less complex

Rear addition: what to watch for

• Rear setback in Redmond NR zone is 20 ft. Many Eastside lots that are 100–120 ft deep have rear yard depth of 50–70 ft after the house footprint — giving only 30–50 ft before the setback kicks in. That’s often less room than it looks on a property survey
• Critical areas: rear yard additions on properties backing to streams or wetlands trigger Redmond’s critical areas buffer requirements, which can extend setbacks 50–200 ft

For detailed cost comparison of second-story additions across the Eastside, see Second Story Addition Architect Seattle Eastside.

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What a Redmond Home Addition Actually Costs in 2026

The Eastside construction market is running 4–6% annual cost escalation in 2026. Redmond follows Bellevue and Kirkland patterns closely — labor costs and subcontractor availability are regional, not city-specific.

Addition Type	Cost per Sq Ft	Notes
Single-story rear addition (standard finishes)	$400–$600	Foundation + framing + finishes
Single-story rear addition (premium finishes)	$600–$800+	Premium kitchen/bath, higher envelope spec
Second story addition (standard)	$500–$700	Structural upgrade + second-floor build
Second story addition (premium)	$700–$900+	Full envelope replacement + premium
Primary suite addition	$450–$700	High MEP content (bath, HVAC zone)

These ranges are all-in construction costs. Soft costs — architecture, engineering, permitting, survey — add 15%–25% on top.

Permit fees for Redmond additions run on Redmond’s valuation-based schedule. A $500,000 addition project pays approximately $8,000–$14,000 in permit fees total. Use Redmond’s online fee estimator at redmondwa.gov/permits for current rates.

Timeline: From design kickoff to permit issuance, expect 4–6 months for a straightforward Redmond addition: schematic design (4–6 weeks), design development and permit documents (6–10 weeks), permit review (5–28 business days standard, up to 12 weeks in busy periods). Construction typically runs 6–12 months depending on scope.

For ADU-specific guidance in Redmond, see our post on ADU design in Sammamish (similar zoning context) and Washington ADU Laws 2026 Eastside.

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What the Architecture Scope Includes for a Redmond Addition

Working with Piper Cole Architects on a Redmond home addition covers:

Feasibility phase:

• Lot coverage, setback, FAR, and height envelope analysis
• Coordination of land survey (required for permit submittal in most cases)
• Critical areas review via King County GIS layers
• Pre-application meeting coordination with Redmond Development Services

Schematic design:

• Floor plan options for the addition scope
• Exterior massing and material direction
• Review of how the addition connects to the existing structure — transition zones, ridge heights, roof plane alignment

Permit documents:

• Architectural drawings: site plan, floor plans, elevations, sections, details
• Coordination with structural engineer (required for any load-bearing changes or second stories)
• Energy code compliance documentation (2021 WSEC as adopted by Washington, effective March 2024)
• Submittal to MyBuildingPermit.com with response to city review comments

Construction administration (optional):

• Site visits at key milestones
• Response to contractor RFIs
• Change order review

The total architect fee for a Redmond addition typically runs 10%–18% of construction cost depending on scope. For a $500,000 addition project, that’s $50,000–$90,000 in architect fees — coordinating a project that, if badly managed, could cost $50,000–$150,000 in change orders alone.

For context on how the Kirkland process differs, see Home Remodel Architect in Kirkland WA and our overview of Bellevue’s building permit process.

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Frequently Asked Questions

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Work With Piper Cole Architects on Your Redmond Addition

David Meade, AIA, NCARB leads Piper Cole Architects, a licensed AIA firm based in Kirkland. We work with homeowners across Redmond, Kirkland, Bellevue, Sammamish, and the Seattle Eastside on additions from 400 to 2,000+ square feet. We know the Redmond Development Services process, the NR zone development standards, and the Eastside construction market.

Start with a consultation — we’ll tell you what your lot can support and what it will cost before you commit to anything.

Contact Piper Cole Architects

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Sources

• City of Redmond, Ordinance 3186 — NR Zone Development Standards Update (January 2025): redmondwa.gov
• City of Redmond, Ordinance 3220 — Middle Housing Code Amendment (June 2025): redmondwa.gov
• City of Redmond, Permit Applications and Development Services: permits@redmond.gov / 425-556-2478
• MyBuildingPermit.com — Redmond residential permit portal
• Washington State Building Code Council, 2021 WSEC adoption (effective March 2024): sbcc.wa.gov