What Portland’s New Density Laws Mean for Trees

The Residential Infill Project (RIP) laws that come into effect on August 1, 2021 leave theoretical space for trees next to multiplexes but don’t stipulate that “open area” must include permeable space for trees. Builders can choose to pave much of the area and, in line with the current tree code, can pay not to preserve or plant trees. Picture new housing surrounded mostly by pavement because tree planting remains, in effect, voluntary. RIP exacerbates the weaknesses in the tree code.

By Kyna Rubin

Trees for Life Oregon supports density that brings more affordable housing to Portland but believes that new housing should be healthy housing. New construction that leaves room for required large-form trees is healthy housing. Big trees shade residents from increasingly hot summers, mitigate heat-island effect, manage storm water, and provide multiple physical and emotional health benefits to everyone nearby.

Climate change makes big trees, which improve urban life now, even more crucial for our future.

Here’s what Trees for Life Oregon has learned about RIP and its potential impact on existing large trees and space for new ones. Much of this information comes from discussions with Morgan Tracy, project manager at the Portland Bureau of Planning and Sustainability.

What RIP Does

RIP responds to Portland’s obligations under Oregon’s middle housing bill, passed in 2019.  The new infill laws open up single-dwelling residential zones in Portland to middle housing, i.e., multi-unit housing up to a fourplex, with the aim of encouraging more affordable, close-in housing for all. RIP increased the number of units that can go on a lot and reduced maximum building area anywhere from a third to a half of what’s allowable today, says Tracy. Builders will have to choose to spread out or build up, but will no longer be allowed to do both. Read more about RIP here. 

Single-family homes and duplexes will share the same building coverage and outdoor area requirements; per tree code, their tree planting area must be 40 percent of the site. RIP requires a developer of a house or duplex to plant two large, four medium, or six small trees.

In contrast, triplexes, fourplexes, or cottage clusters in single-dwelling zones will be required to have only half that tree planting area, or 20 percent of the site, and developers will be required to plant only one large, two medium, or three small trees.

Sounds fine, but here’s the rub: Those requirements are only theoretical, call them voluntary, because Title 11, the tree code, allows developers to pay not to preserve or plant trees.

It is technically possible to pave an entire single-dwelling zoned lot, as it is today, pre-RIP, even as RIP gives the impression of more space for trees.

Further, in all residential zones the only outdoor area required is the 250 square feet remaining after maximum building coverage, one portion of which must be a 12-foot square to allow a continguous space for relaxation or recreation that is not in the property’s front setback. That 12-foot square, says Tracy, is typically located at the back of the lot.

Here’s the thing about outdoor area in the zoning code: Title 33.110.240.C.2 states that outdoor area “must be surfaced with lawn, pavers, decking, or sport court paving which allows the area to be used for recreational purposes. User amenities, such as tables, benches, trees, planter boxes, garden plots, drinking fountains, spas, or pools may be placed in the outdoor area. It may be covered, such as a covered patio…” [italics by TFLO]. Life-giving trees are rated as equivalent to outdoor tables. And few trees can grow in a covered area.

Trees are, in effect, rated as equivalent to outdoor tables.   

Someone familiar with City code might wonder why minimum landscape requirements, which apply to other zones, aren’t imposed on RIP’s newly densified single-dwelling zones. “Landscaping area that ensures a minimum permeable area that includes vegetation is a requirement in multi-dwelling and mixed-use zones,” says Tracy, but not in single-dwelling zones.  

However, landscape requirements as applied to those other zones don’t mandate that builders plant large trees. The rules call for one large tree per 30 linear feet, or one medium tree per 22 linear feet, or one small tree per 15 linear feet. Trees of different sizes can be combined to meet the standard. And up to half of the required landscape area can be provided by raised planters or up to a quarter by eco-roofs; neither is an appropriate medium for large trees. So directing current landscape requirements to single-dwelling zones wouldn’t fix the problem.

Together, the tree code and zoning code increase the likelihood that more Portland residents will be living without nearby big trees now and in the future.

What’s RIP2?

RIP2, not yet approved, aims to satisfy the same state middle housing bill mentioned above. RIP addressed most of that bill’s requirements, but two residential zones (R10 and R20) were not included, nor were two types of residential development--cottage clusters and townhouses. The project will launch in summer 2021, with proposals to the Planning and Sustainability Commission in the fall and to City Council by spring 2022. The state deadline for adopting the new rules is June 30, 2022.

Will RIP2 affect trees? R10 and R20 refer to residential lots that are 10,000 square feet and 20,000 square feet, respectively. These are very large lots mostly found in outer Northeast, outer Southeast, and in Southwest. They may hold tree groves, says Morgan Tracy, but because “significant additional development is not very likely”--they’re not close to services, amenities, and transit--they weren’t covered in RIP1.

Development on these sites is unlikely, he says, because some of these lots are located in environmental zones and are therefore protected; they are prone to natural hazards such as floods, landslides, and wildfires; and creating sewer, water, and street infrastructure would be challenging.

However, the effects on tree space when RIP2 addresses cottage clusters and townhouses are currently unknown, according to Tracy. “There are some limitations in the state law that could tie our hands on certain rules for these housing types. For example, cottage cluster rules cannot include building coverage limits.”

Code Changes to Temper RIP’s Impact on Space for Trees

Even prior to RIP, which takes effect this August, concrete jungles are already in evidence next to new housing around the city. Trees for Life Oregon is developing a list of desired changes to the tree and zoning codes. But RIP will likely exacerbate the lack of large trees next to new housing. To address this, we suggest that:

● The tree code needs to catch up with the new housing types that RIP allows. Apply the same 40-percent-planting-area standard to multiplexes that govern one- and two-family structures. This would double the amount of planting area required for multiplexes while applying the same standards for housing ranging from one house to fourplexes, as mandated by the state bill, thus avoiding giving favorable treatment to single-family homes.

● The zoning code should limit the amount of outdoor area that can be paved within the range of housing types RIP permits in residential zones in order to leave adequate space to accommodate at least one medium- to large-form tree. Also, permeable area in favor of medium- to large-form trees should be reconciled with on-site storm water facility mandates.

However, until and unless the tree code eliminates builders’ option to pay a fee to remove or not plant trees, decent-size trees in new infill sites are a very iffy proposition.

In spring 2021, Urban Forestry will present City Council a project scope to update the Urban Forestry Management Plan and rehaul the tree code. Although code changes won’t happen for a few years, now is the time to be specific about the changes we want to see. Urban Forestry won’t be overseeing amendments to the zoning code. But when tree code provisions are improved, zoning code provisions and bureau practices should be revised to encourage big tree preservation and permeable space preservation for future big trees.

Revised August 15, 2021