Commercial Tenant Improvement Architecture in Seattle: What Businesses Need to Know

A commercial tenant improvement (TI) is any renovation to a commercial space — office, retail, restaurant, medical, or industrial — to prepare it for a new occupant or adapt it for a different use. In Seattle, virtually all commercial tenant improvements require a building permit and architectural drawings. This guide explains the process, costs, and what to expect when working with an architect on a commercial TI.

When a Commercial TI Requires an Architect

The City of Seattle requires a building permit for commercial tenant improvements that involve:

• Any structural change (wall removal, opening enlargement, load addition)
• Change of occupancy type (e.g., office to restaurant, retail to medical)
• Plumbing modifications (adding bathrooms, kitchen, or additional fixtures)
• HVAC system modifications
• Electrical panel or service upgrades
• Accessibility upgrades when triggered by alteration threshold
• Any work over $25,000 in value in a fire-rated assembly area

Cosmetic work — paint, carpet, light fixture replacement in kind — typically does not require a permit. When in doubt, the answer in Seattle is usually yes, a permit is required.

The Commercial TI Process

Space Assessment

Before design begins, we assess the existing space: square footage, existing mechanical and electrical systems, structural grid, ADA accessibility path of travel, and any code issues that need to be addressed regardless of the proposed scope. Many Seattle commercial spaces — particularly in older buildings — have deferred accessibility compliance that becomes required when the space is altered beyond certain thresholds.

Programming

We work with you to define the program: workstation count, conference room requirements, reception configuration, kitchen and break room, server room, private offices, storage. For retail, we define the merchandise zones, fitting room count, checkout configuration, and stockroom. For restaurant, we address front-of-house covers, bar seating, kitchen layout, and code-required elements (hoods, grease interceptors, health department requirements).

Space Plan and Design

We develop the space plan — the fundamental layout of the improved space — and the design: materials, finishes, ceiling design, lighting concept, and architectural elements. Commercial spaces need to communicate brand identity while meeting functional requirements efficiently.

Construction Documents and Permit

We produce permit-ready construction documents for the City of Seattle’s Department of Construction and Inspections (SDCI). Commercial TI permits are reviewed by commercial plan reviewers — a separate queue from residential. Review times for commercial TIs in Seattle currently run 4–8 weeks for standard projects.

Bidding and Construction Administration

We assist with contractor selection and provide construction administration — responding to contractor questions, reviewing submittals, and conducting site visits to verify the work matches the drawings. For commercial TIs, construction administration is especially important because the contractor is typically working on a tight timeline with landlord incentives at stake.

Seattle Commercial TI Costs (2026)

• Office TI (standard finishes): $80–$150 per sq ft construction cost
• Office TI (high-end finishes): $150–$250 per sq ft
• Retail TI: $100–$200 per sq ft
• Restaurant TI (full kitchen buildout): $250–$500 per sq ft
• Medical office TI: $200–$400 per sq ft
• Architectural fees: 8–12% of construction cost for full-service TI

Tenant Improvement Allowances

Many Seattle commercial leases include a tenant improvement allowance — a landlord contribution toward the cost of improvements. TI allowances are typically expressed as a dollar amount per square foot ($40–$80/sq ft is common in 2026 Seattle). The allowance is often insufficient to cover the full cost of a quality build-out, particularly for specialized uses like restaurants or medical offices. Architectural drawings help you maximize the value of the TI allowance by ensuring work is done right the first time.

Restaurant Architecture in Seattle

Restaurant TIs are among the most complex commercial projects due to the concentration of specialized systems: commercial hood exhaust, grease interceptor, walk-in refrigeration, commercial cooking equipment, health department approval, and liquor license considerations. Seattle’s health department (Public Health Seattle-King County) requires a separate plan review for all food service establishments. We coordinate the health department submission as part of our standard restaurant TI services.

Working with Piper Cole Architects on Your Commercial TI

Piper Cole Architects provides commercial tenant improvement architecture for office, retail, restaurant, and mixed-use projects across Seattle and the Eastside. We understand Seattle’s commercial permitting process and the specific requirements of different occupancy types. Our commercial practice is complemented by our residential expertise — many of our commercial clients are also homeowners who come to us for both projects.