Portland rules that became effective in March 2020 aim to marry increased outdoor space with more affordable housing and offer a transfer of development rights option for preserving trees on private property.

By Kyna Rubin

Outdoor play space that’s not a parking lot. Intact stands of old Douglas-firs. More affordable housing. 

That’s what low-income apartment dwellers east of 82nd Avenue told the City and the Oregon Public Health Institute they wanted when asked several years ago how livability could be improved in their part of town. 

One result so far? A set of codified rules originally called Better Housing by Design that has been in effect since March 2020. The new rules seek to improve multi-dwelling housing for the low-income families and people of color who disproportionately live in it.

Enhancing Quality of Life for East Portland Apartment Dwellers

Eighty percent of new housing units constructed in Portland between now and 2035 will be in apartment buildings, and one-third of multi-dwelling capacity lies in east Portland, where lots are usually larger than those closer in and often contain large trees, typically Douglas-firs. The rules apply to multi-dwelling zones across the city but seek to preserve tree groves in east Portland.

Instead of relying only on the goodwill of developers, the changes require builders on large sites to leave more outdoor space for people and trees, says Bill Cunningham, the Bureau of Planning and Sustainability’s project manager for Better Housing By Design. The changes limit asphalt paving and parking-lot size in multi-dwelling zones citywide. Large sites more than 20,000 square feet are required to set aside 10 percent for outdoor common area. That’s similar to pre-World War II courtyard apartment houses.

The rules suggest, but don’t require, building right up to the street but leaving a large, treed common space in the shared backyards of multiplex residents.

To help preserve the Douglas-fir groves that sometimes lie mid-block in expansive sites, the rules suggest, but don’t require, building right up to the street but leaving a large, treed common space in the shared backyards of multiplex residents. 

The incentive part of the equation rewards builders now required to set aside more outdoor space for using that space to preserve established trees or groves. That preservation earns them the new right to transfer development rights (TDR), a process that cities typically apply to preserving historic homes, and that local governments around the country apply to growth management and preserving farmland, not urban trees per se. According to California-based TDR planning consultant Rick Pruetz, who has tracked TDR nationwide, the specific application to trees is “something new.”

The transfer provision sounds terrific, in theory. As of January 2021, however, Laura Lehman of the Bureau of Development Services Planning and Zoning section was unaware of any applications for the TDR option. Nor does the bureau have any plans to hold workshops or advertise these potentially tree-saving opportunities now part of the multi-dwelling residential zones chapter of Title 33, the zoning code.

The Affordable Housing Exigency 

Because of the community’s call for more affordable housing and its inclusion in the 2035 Comprehensive Plan, prioritizing housing with affordable units became a big part of this set of codified changes, says Cunningham. At the same time, urban heat-island research is showing the ill effects of low tree canopy on vulnerable populations. The policy goal is to encourage homeowners and builders to preserve trees on one site while providing more affordable housing units on another. 

The policy goal is to encourage homeowners and builders to preserve trees on one site while providing more affordable housing units on another.

A previous tree-saving incentive wasn’t effective. The City had provided a bonus for preserving trees that would allow bigger development on the same site. But few developers used it, says Cunningham. They found it too hard to intensify development while preserving trees and the root protection zones they require. Thus the decision to let builders transfer that right to another location.

How Transfer of Development Rights Work

The transfer can take place in different ways. If you’re a builder who owns multiple properties, you can transfer the rights from one multi-family-zoned site to another (or to a commercial/mixed use site) where more intense development is allowed and there are fewer if any trees to remove such as on a high-traffic street. Or you could sell those development rights to another developer.

The number and size of the trees flagged for preservation, as well as the sending site’s zone type, determine how much development potential can be legally transferred from one site to another. For instance, preserving a tree with a diameter of 12 to 19 inches earns a transferable floor area of 1,000 to 4,000 square feet, depending on the sending site zone; a preserved tree that’s 36 inches in diameter or more gets you transferable floor area of 4,000 to 16,000 square feet (see Title 33.120.210, Table 120-4).   

If you’re not a developer but own a multi-family-zone site containing trees 12 inches or more in diameter and you want to preserve your trees from development, you can tag the ones you want to save and sell that lost development potential to a developer who can use them on another site. The receiving site owner gets to more fully use the permitted height. They can’t expand the building footprint, which for the most common multi-family zone can only cover about half the lot.  They can only build up, going to three stories from the effective limit of two, says Cunningham. 

Talks with east-of-82nd residents revealed they are more concerned about the loss of Douglas-firs than about buildings along arterial roads getting taller, according to Cunningham. 

The development potential reduction and tree preservation requirement last for at least half a century, says Cunningham. They are recorded in a covenant and in the property deed. After development rights are transferred from sending site to receiving site, the sending site never gets those rights back. “Cutting down trees even after fifty years does not allow the property owner to build what the zoning originally allowed before the transfer,” he says.

TDR for tree preservation is an added incentive for builders to more fully use the allowed height and thereby increase floor space and, presumably, their bottom line. Developers already can earn development bonuses by providing a certain percentage of affordable units, creating accessible units for elderly and disabled residents, or including moderate-income family-size units. 

City planners tried to keep the “by right” scale of multi-family structures somewhat limited to entice builders to seek a development bonus or a TDR in the first place, says Cunningham. Both of these credits encourage increased affordable housing but TDR does so while also engaging in another public good—tree preservation. 

Devising incentives to retain the Douglas-fir groves in east Portland matters to the people who live there and to a city facing climate crisis.

East Portlanders Like Their Douglas-firs

Devising incentives to retain the Douglas-fir groves in east Portland matters to the people who live there and to a city facing climate crisis. Many Douglas-firs in east Portland are unprotected. They lie in flat areas far from streams or hillsides that might place them in designated environmental zones where they would be protected.

Saving these trees is a way to respect one of east Portland’s unique characteristics. “The heritage of a place is also the natural heritage, not just the built heritage,” area residents told City planners, says Cunningham. The Douglas-fir is Oregon’s state tree, and the David Douglas school district is named for the Scottish plant collector who introduced its seeds for cultivation in England.

The Match-making Challenge

So far, builders haven’t taken the City up on the TDR idea. It takes time for developers to catch on to new code provisions. But without City efforts to educate or raise awareness about this, the opportunity will likely sit unused. 

One of the five key elements to a successful TDR program is that “people need to know about it,” says Michael Murphy, TDR program manager for King County in Washington State. Murphy’s office runs a bank that buys and sells TDR—for rural land, not trees--from properties the county has purchased through easements. The money earned from selling TDR helps the county recoup some of its investment in land conservation. 

How to find a local champion who will guide parties through the TDR process? If the City’s not going to take the lead, who will?

The biggest challenge for Portland is connecting sellers and buyers of development rights—matching property owners who want to preserve their large trees by selling development rights with builders who’d like to add a floor to a structure on an arterial street. How to find a local champion who will guide parties through the process? If the City’s not going to take the lead, who will?

At present, says Cunningham, a number of land use law firms are doing some of this matchmaking. But more needs to be done. (Neither the local lawyers involved nor the Home Builders Association of Portland responded to requests for comment.)

“It’s hard for these regulations to do everything you want them to on their own. It’s always helpful if something’s coming from the community side,” he says. That’s what drove some of the success of historic preservation. Cunningham thinks that TDR would gain traction if a local non-government organization such as a land trust could promote, administer, and enforce the mechanism. Developers would then know where to go to find who has trees and development rights to sell.

Do Other Code Changes Make Including Space for Big Trees More Likely?

The new rules for Portland’s multi-dwelling zoning code that include TDR are a well-intentioned response to what low-income families living in east Portland apartment complexes say they want. The new required outdoor spaces are a positive. But many qualifications nibble away at the “outdoor space” requirement: 

--The 10 percent of large sites that must now be reserved for outdoor common area can include courtyards, which may or may not be designed with large trees in mind. 

--Courtyards, balconies, and indoor community rooms may count as outdoor space. 

--Though balconies and indoor community rooms don’t count toward minimum landscape requirements, there’s no guarantee that developers will use the new rules to design for large trees when there’s no requirement for the permeable area that trees need for their root zones.

--Eco-roofs, raised courtyards, and raised storm water planters can now meet up to 50 percent of landscape requirements, so it’s unclear how much room developers will leave for large trees. 

Cunningham doesn’t pretend that the new rules fix all the problems in the tree code, including its inability to address equity and climate issues that weren’t on the City’s radar when Title 11 was drafted. He does think the new zoning code rules supply new tools to preserve trees on large east Portland lots. How and if developers respond remains to be seen.

There may be opportunities to facilitate the transfer of development rights to preserve trees. Readers who have ideas about this topic or are interested in learning more can contact Trees for Life Oregon at treesforlifeoregon@gmail.com.