Desks to Dwellings: Tackling Office-to-Residential Conversions

One of the most rewarding aspects of engineering is witnessing and contributing to transformations.

Historic landmarks transform into modern hotels, flood plains morph into ecocentric school campuses, horse stables renovate into office spaces. Most recently, office-to-residential conversions have been top of mind. These conversions are important to large cities across the nation, but especially Seattle as they simultaneously address the need for more housing and to alleviate office vacancies.

Two calendar eras define our times: BC and AD, also known as “Before COVID” and “After Disease.” (In contrast to popular belief, AD isn’t accurate because COVID certainly is still around.) Sometimes it’s hard to remember what everyday life was like in the BC era, but what’s certain is that COVID-19 shook our world. Forced to stay home, many of us learned how to work from unprepared corners of our own apartments and houses. (Shoutout to IT pros everywhere for adapting to remote work and enabling our teams’ collaboration to continue!) It forced us to rethink the importance of our homes, and brought to light the need for more housing, especially as Seattle’s rental vacancy rates dipped to 3-4 percent (below the healthy percentage range of 5-10 percent). Even as a semblance of normalcy returned, the corporate landscape is forever changed. Many employees continue to work remotely, leaving commercial buildings across the U.S. deserted.

And what’s to be done with these vacant spaces? Many of these office buildings are being studied to determine whether they can be converted into multi-unit residences. Of course, this process isn’t as simple as adding a bed and calling it a day. There are high costs, design headaches, and a maze of regulations to work through—not just within the AEC industry, but also among government officials. In Seattle, Coughlin Porter Lundeen is up to the challenge. Our experience and expertise in navigating office-to-residential conversions facilitates design and municipal challenges.

From 9-to-5 to 24/7 Comfort: Nationwide Incentives for Office-to-Residential Conversions

As cities across the U.S. tackle commercial building conversions, government bodies and municipalities are making efforts to help via incentive programs. These programs attempt to streamline the process and speed up the redevelopment of vacant office buildings. Typically, programs help with funding, or they provide property tax abatement. Each city has their own version and process for programs. We break down New York City, San Francisco, and Seattle’s incentives below:

New York City

  • If approved, the City of Yes for Housing Opportunity Plan will update NYC’s outdated zoning code. According to NYC’s Department of City Planning, the current code prevents buildings constructed after 1961 or offices outside central business areas from converting. City of Yes would legalize conversions for buildings built through 1990 and in areas where residential use is allowed, making conversions easier and more prolific throughout the five boroughs.
  • City of Yes went through public review, and the City Planning Commission approved it this year.
  • Next steps: City Council will hold its final vote before the end of 2024.

San Francisco

  • In March 2024, Proposition C passed, which waives the city transfer tax on office-to-residential conversions. The transfer tax can be up to 6% on transactions that surpass $25 million, but won’t be applicable to converted buildings, according to the San Francisco Bay Area Planning and Urban Research Association.
  • Prop C waives the tax for the first 5 million square feet of non-residential space converted, making such projects less costly.

Seattle

  • In July 2024, City Council eliminated obstacles for developers who are transforming office buildings into housing. Design reviews? Gone. Development standards? Waived. This reduces the amount of time a project spends in approval purgatory, which can be months!
  • With the exception of Midrise and Highrise zones, Mandatory Housing Affordability (MHA) requirements were waived and can help lower project costs. MHA requires that a developer provides either: 1) affordable housing units in new development projects (performance option), or 2) pays into a fund that will support affordable housing development (payment option). Maintaining these requirements in Midrise and Highrise zones makes sense because the commercial buildings in these areas won’t accommodate office-to-residential conversions as well as those in other zones.
  • In addition to cost incentives, the new policy allows small expansions for existing structures to accommodate new residential use.

In the last 20 years, 1.3 percent of total commercial space in the Seattle area (which includes 14 office buildings), converted or has plans to be converted into housing, hotels, or life science labs. Zoned for mixed use, Coughlin Porter Lundeen’s Queen Anne Plaza project is among them, currently in permit review.

“Bracing” Ourselves for Office-to-Residential Conversions

In October 2023, as well as conducting a structural and seismic evaluation of 201 Queen Anne Avenue, we studied whether it was possible to convert the existing office building into a multi-unit residence. We regularly conduct similar feasibility studies for those interested in office adaptive reuse projects. The team’s depth of experience and access to archival drawings and reports are essential assets to providing an accurate assessment.

Structural Principal Bryan Zagers is our in-house expert for office-to-residential conversions. “I walk every inch of the building with the team. Because we have so much experience and such a strong archive of drawings, I can give them an initial evaluation quickly. It’s an invaluable deliverable for a developer considering a residential conversion. Our evaluation gives them a strong starting point and helps manage expectations about what a renovation will truly require.”

The Queen of Conversion Candidates

Located at 201 Queen Anne Avenue, the existing vacant four-story office building will be adapted into a revitalized 74-unit apartment building. The Seattle Times reports that recent commercial tenants were the contractors who built Climate Pledge Arena and an employee benefit plan administrator. According to The Urbanist, the City of Seattle hopes that this year’s change in legislation will result in 1,000-2,000 new homes in the next seven years. With a relatively small floor plate and a two-story parking garage tucked into the sloped site, 201 Queen Anne Avenue is an ideal candidate for adaptive reuse as an apartment building. As office-to-residential conversions become more common in Seattle, it’s more likely that two- to six-story buildings will be rehabilitated, in contrast to New York City’s fleet of high rises. Seattle’s zones which allow conversion projects, as shown in the map above, typically have buildings with fewer floors. In contrast, New York City has a taller building stock in areas where conversions are permissible.

3D view of 201 Queen Anne Avenue (right), courtesy of Board & Vellum.

Responsible, Resourceful Design

With cost being a huge constraint to conversion projects, the design team chose to keep as much as possible from the building’s existing good bones, while balancing necessary changes to create cozy homes for future residents. The architect, Board & Vellum, is keeping the EIFS façade, but painting it from an outdated 1980s tan to a sleek onyx. Although most of the window system will remain, a certain amount of the glazing will be replaced with operable windows to allow fresh air into apartment units. We were allowed to create a small expansion of the existing structure and added a fifth-floor penthouse with wood structure on top of the existing concrete system.

Out with the... wait. We can use that!

Rather than removing any part of the outdated structural and seismic system, Coughlin Porter Lundeen is mitigating the existing reinforced concrete system by incorporating high-tech earthquake upgrades consisting of fiber-reinforced polymer (FRP) wraps and fluid-viscous dampers (FVD).

“In an earthquake, the building movement would have failed the existing interior columns, so we had to fiber wrap them. Basically, the fiber wrapping doesn’t let the column rip apart because it’s constrained by this outer layer of reinforcing,” explained structural project manager Zach Whitman.

Think: layers of carbon fiber—thin but strong. FVDs, on the other hand, look like braced frames but act like giant shock absorbers by slowing down the building’s movement during an earthquake. Seismic upgrades can be a huge cost for conversion projects, but Coughlin Porter Lundeen’s unique expertise empowers us to make informed, cost-conscious decisions when developers bring us on as a consultant. Our combined portfolio of renovation work and multi-unit housing gives us the upper hand in office-to-residential conversions because these market types require a simultaneous breadth of experience and creative problem solving.

A City Partnership

As 201 Queen Anne Avenue progresses, we continue to rely on our civil and structural design expertise, our strong relationship with city officials, and our understanding of building codes. The project is currently in permit review with construction expected to kick off next year. Due to the nature of office-to-residential conversions, coordination with the city is particularly important because these projects often involve a negotiation process with the city. In some ways, we act like owners’ reps as we navigate the negotiation process with the City to help the design team understand their requirements, while making a case for our proposed design during the review process.

Even though Coughlin Porter Lundeen has successfully worked on adaptive reuse projects in the past, we’re excited to be part of the first wave of office-to-residential conversions under Seattle’s new policies!

Zach Whitman says, “Everyone benefits. You want more housing, and you want to have these buildings not be vacant.”

These projects push the boundaries of how we take advantage of our own experience to address big picture issues like providing housing stock and tackling office vacancies. It’s a privilege to contribute to Seattle’s ever-evolving urban fabric.