By Kristen Scott
Kristen Scott is Managing Partner and Senior Principal of Weber Thompson where she heads the Workplace studio. As Managing Partner of Weber Thompson for more than 25 years, she has overseen the growth of the firm from its beginnings to the sustainably focused 60 person multi-disciplinary firm it is today.
For building owners trying to lease out a space and for small business owners, one of the biggest budget items is the cost to build out a new space, aka the tenant improvement (TI). To support the return of retail and restaurants to fill empty commercial spaces, the City of Seattle has adopted a new ordinance to help reduce potential construction costs.
Particularly in an older building, whether you have to meet current Building codes can have a huge impact on project costs for a TI. The Seattle Existing Building Code Section 311 has a list of criteria used to determine whether a proposed tenant improvement will be considered a Substantial Alteration or not. A Sub-Alt determination triggers a cascading list of additional work needed to meet current codes. It can be a budget buster, especially for small TI’s.
As of late October 2025, a new City Ordinance modifies several of the Sub-Alt criteria, a welcome relief for both building owners and new tenants!
Highlights include:
- No Substantial Alteration required for buildings or spaces less than 7,000 GSF
- Buildings vacant longer than 24 months no longer trigger a Sub-Alt.
- Partial change of occupancy less than 20% of gross area will not trigger a Sub Alt.
- HVAC conversion from fossil fuel or electric resistance to a heat pump will not trigger a Sub Alt.
Read the official announcement from the City of Seattle, or reach out to us to discuss your TI needs!