Seattle Office-to-Residential Conversions: Key Insights from Industry Leaders

Adaptive reuse, especially office-to-residential conversions, responds to office vacancies, housing shortages, and sustainability goals. Held in the historic A&D Building (more commonly known as the Old Spaghetti Factory), the adaptive reuse panel shared their industry knowledge to demystify office-to-residential conversions with these key points:

The best candidates for conversions are determined by their structural system, core-to-window distance, building age, floor plate depth, and location. The right combination of these variables determines whether a building can be converted into housing for a reasonable price and timeline. Gensler, a pioneering architecture firm leading office-to-residential conversion research, developed a 12-question survey that analyzes these factors to quickly determine whether a building is worth converting.

For example, apartment buildings benefit from narrower floor plates to allow sunlight to permeate throughout each unit, rather than deep floor plates which result in narrow, dark apartments. In addition to the existing building conditions, developers consider the availability of surrounding amenities to make sure the area is livable and convenient for future residents.

Cities recognize the inherent value of office-to-residential projects because they simultaneously provide more homes while revitalizing underutilized buildings. Realizing the value of such projects, municipalities offer cost or regulatory incentives to encourage sustainable adaptive reuse development.

Projects work best when properties are purchased at significant discounts, so that other costs go towards renovating the building. Overall project expenses decrease with tax deferrals, such as historic tax credits where applicable. For example, Seattle City Council also offers sales tax exemptions for conversions with 10% of apartment units dedicated to affordable housing throughout 10 years.

Streamlined city legislation eliminates design review from the permitting process. This makes these renovations often quicker than new construction, but they require thorough due diligence and early investigation. This upfront time ultimately avoids costly surprises.

Adaptive re-use is also a prime candidate for alternative delivery methods such as design-build which can provide additional schedule reductions, increased scope coordination, and enhanced project outcomes.

In the City of Seattle, an existing building’s change of use to a more hazardous occupancy—in this case from commercial to residential—triggers a Substantial Alteration to upgrade seismic, fire, life safety, energy conservation, and accessibility requirements. For architects and developers interested in transforming offices into homes, pre-submittal meetings with the city lead to success when approached with specific proposals, not open-ended questions. Coming to the City with clear, project-specific requests helps the team focus on negotiations and identify what is truly needed for the conversion, while broad or open-ended questions often result in conservative responses that increase requirements and ultimately project costs.

“Built within the Substantial Alteration code is flexibility. The City of Seattle has a process where they encourage negotiation. The real way to take advantage of that is with a pre-submittal conference,” Coughlin Porter Lundeen Structural Principal Bryan Zagers said. “You study the building early in the project so you get some certainty and can move forward with design. With that in mind, you can identify what are the important things to ask for from the City.”

The right structural engineering partner navigates the negotiation process for the owner with the City. In addition to helping the design team understand code requirements, they can make a convincing case for the proposed design during the project review process. Understanding code requirements allows the design process for office-to-residential projects to be more streamlined and leads to less unforeseen circumstances.

“In early phases, we’re asking the hard questions to make sure that we’re not going to be surprised later. If it comes in too late, we won’t be able to mitigate it. We work hard and commit a lot of resources up front to make sure that the project is set up for success,” Gensler Principal Ryan Haines said.

Sometimes surprises can be a good thing, though. Some older buildings are structurally stronger than expected and can support added penthouses or roof amenities, for example. In other cases, selective demolition reveals unexpected structural reinforcement in walls. Regardless, the bottom line is to plan early because surprises do happen.

The most sustainable option is to preserve and retrofit an existing building rather than build a new one.  About two-thirds of Seattle’s current building stock will still exist in 2050, so reuse strategies keep buildings alive while addressing critical needs such as housing. In addition to preserving a building’s charm and character, repurposing existing buildings lowers embodied carbon and avoids demolition waste. They hit the R’s of sustainability: reduce, reuse, recycle, rethink, refuse, and repair. This applies not only to material waste in everyday lives, such as what is considered trash versus recycling; but buildings, too.

Engaging office-to-residential conversion experts helps your team make informed, strategic decisions, whether you are wondering if a building can be converted or are ready to start designing. Coughlin Porter Lundeen leverages their seismic and structural engineering expertise, as well as familiarity with regulatory requirements, to guide developers and architects throughout the course of the project’s duration. As local Seattle civil and structural engineers, their database of the city’s historical buildings facilitates the adaptive reuse process by quickly answering due diligence questions ahead of time.

Interested in learning more? Feel free to reach out to Bryan Zagers directly with any questions.