Portland, Oregon

(Profiled 3-2-21)

Portland, Oregon, population 645,291 (2019), uses TDR in several planning districts to achieve various goals including the preservation of housing, open space, viewsheds, riparian corridors, habitat, environmental resources, historic landmarks, infrastructure capacity, and trees.

Northwest Hills – Portland adopted its first TDR program in 1991 as an implementation tool for its Northwest Hills Plan. The planning area includes a wooded bluff on the west side of the Willamette River that creates a natural backdrop for seven miles of the city center. The plan aims to maintain the character and natural resources hereby limiting development within an Environmental Protection overlay where land zoned for single-family residential dwellings can become TDR sending sites by reducing or eliminating onsite development by covenant. 

The density is transferred at a one-to-one ratio by planned unit development applications submitted for the sending and receiving sites. Receiving sites are zoned Residential Farm/Forest (RF) that are within the Northwest Hills district but not covered by the Environmental Protection overlay. Baseline in the RF zone is one unit per two acres. Transfers boost density to one unit per acre for qualified sites. 

Johnson Creek – In 1996, Portland adopted the Johnson Creek Basin Plan aimed at shifting development away from sensitive environmental areas and locations vulnerable to flooding. Sending sites can transfer the density allowed by the underlying zoning to any property in the Johnson Creek district that is not zoned Residential Manufactured Dwelling Park and not within selected subdistricts, restricted by the Environmental Protection overlay, or within a flood hazard area. Transfers are processed as planned development applications for both sending and receiving sites. TDR can increase development on receiving sites up to 200 percent of baseline density. 

In competition with TDR, developers here can also gain density by building attached units that meet specifications for sewer, water, and storm water management located within ¼ mile of a transit street or transit way. In addition, the incentive to use TDR in the Johnson Creek district has been reduced by programs that buy out the owners of flood prone properties.  

Landmarks – Portland encourages the preservation of historic landmarks using procedures that vary depending on the zoning districts involved. For example, in multi-dwelling residential zones, sending sites with qualifying historic resources can transfer unused FAR plus 50 percent of the maximum FAR allowed by the site’s zoning if the building is seismically safe or the owner executes an agreement to meet seismic safety standards. Sites in any of nine zones can receive transferred FAR on a one-to-one basis up to the maximum FAR increase specified in the code for all types of bonuses, which varies between zones.

Affordable Housing – Portland uses TDR to motivate the preservation of housing affordable to households earning no more than 60 percent of area median family income. In the multi-dwelling residential zones, sending sites with affordable housing can transfer unused FAR to receiving sites subject to overall limits on the total increase in FAR allowed by TDR and other bonuses.

Trees – Portland uses TDR to motivate the preservation of trees that are at least 12 inches in diameter and certified as healthy by the City Forester or a certified arborist. In Portland’s multi-dwelling residential zones, the tree owner must covenant that the trees will be preserved for at least 50 years. A tree under covenant must be determined to be dead, dying, or dangerous by the City Forester or a certified arborist before being removed and must be replaced within 12 months of removal. Table 120-4 spells out the amount of floor area that can be transferred for three categories of tree diameter in four different zoning districts. At the low end of this table, 1,000 square feet of floor area can be transferred for each tree between 12 and 19 inches in diameter in the RM1 zone. At the high end, 16,000 square feet can be transferred for each tree 36 inches or greater in the RM4 and RX zones. However, the total floor area transferred cannot exceed the unused floor area of the sending site. The receiving area provisions in the multi-dwelling residential zones are limited in the total increase in floor area achievable via TDR and all other allowed bonuses.   

Central City Plan District – The Central City Plan District alone consumes 108 pages of Portland’s zoning code. In 2007, Portland commissioned a study to explore whether the numerous options for gaining additional development potential were accomplishing the goals of this district (Johnson-Gardner 2007). The report characterized the Central City district as having 18 bonus options and six transfer options adopted over the span of 20 years. The bonus options at that time included additional floor area for projects that provide: 1) residential units in target areas; 2) locker rooms; 3) daycare; 4) rooftop gardens; 5) percent for art; 6) water features/fountains; 7) eco-roof; 8) middle-income housing; 9) affordable housing; 10) Willamette River Greenway; 11) large household dwelling units; 12) open space; 13) open space funds; 14) large dwelling units; 15) small development site; 16) below-grade parking; 17) retail space, and 18) theater space within Broadway Theater Target Area. The Johnson-Gardner study identified the following six mechanisms as Central City FAR Transfer Options as they existed in 2007.  

  1. Abutting Lots Transfer – This option allowed FAR potential to be shifted between abutting lots allowing additional density on one or more of these lots as a way of creating cohesion and place making in larger developments. Generally, maximum transfer was 3:1 FAR bonus.
  2. Single Room Occupancy (SRO) Transfer – The unused FAR from a building covenanted to remain SRO could be transferred and used to generally gain an extra 3:1 FAR at receiving sites throughout the Central City subject to certain restrictions: FAR from RX could transfer to RX, EX or CX districts but could not receive FAR transferred from the EX or CX zones. The Single Room Occupancy (SRO) housing option was used at least once, successfully preserving the Athens Hotel as SRO units in 1990. 
  3. Historic Landmarks Transfer – Unused floor area from a designated landmark could be transferred to receiving sites in the same neighborhood but not further than two miles according to the 2007 study. The receiving site could gain up to a 3:1 FAR bonus with some exceptions.
  4. Residential Floor Area Transfer – Owners of residential units in Central City could transfer unused FAR allowing a general increase of FAR 3:1 on receiving sites anywhere in the Central City. The 2007 study noted that this mechanism was adopted at a time when Central City residential development had stalled. The Johnson-Gardner study considered this to be the most versatile transfer option given the large number of potential sending sites.
  5. South Waterfront Transfer – This option allowed abutting or non-abutting receiving sites in the South Waterfront sub-district to achieve extra FAR and to exceed the typical bonus of 9:1 FAR maximum for FAR transferred from the Willamette River Greenway. The Johnson-Gardner study noted that the ability to exceed 9:1 FAR made this option particularly attractive and that it had experienced some use by 2007.
  6. Central City Master Plan Transfer – This option allowed FAR from multiple sites to be distributed throughout a master planned development that could be several blocks in size. Unlike the Abutting Lot Transfer, this option could involve parcels throughout the Central City and there was no limit on the FAR that could be transferred and used on receiving lots as long as the city determined the proposal to implement the Central City Plan. For example, the Central City Master Plan tool was used to shift development potential from The Edge, a building housing an REI outlet, to a larger building known as the Elizabeth located seven blocks away. In another example, the five-block area known as the Brewery Blocks were treated as one site, allowing FAR to shift in a way that transferred FAR from two landmarks, the Brewhouse and Armory, to new buildings in this complex.

The 2007 report concluded that the six transfer options and 18 bonus options were in competition with each other and that developers logically preferred to use the cheapest way of gaining additional FAR. Comparing the 18 bonus options with one another, the Johnson-Gardner study found that the locker room bonus was particularly attractive to developers since it generated 40 square feet of bonus floor area per square foot of amenity, a higher ratio than all the other 17 options combined. On a cost per square foot of bonus floor area basis, the locker room option (at $6 per square foot of bonus floor area) and the eco roof option (at $8 per square foot) were cheaper than all the other bonus FAR options. With the exception of a bonus for market-rate residential, (which was not likely to change developers’ plans), the report noted that the locker room and eco roof bonus options were used more frequently than other bonus FAR options. The locker room and eco roof FAR options were also cheaper than the transfer FAR options, which Johnson-Gardner estimated at ranging from $6.50 to $18.00 per square foot and averaging $10.00 per square foot in 2007. 

This report also reconfirmed that developers gravitate toward bonuses that add value to their projects rather than community benefits at off-site locations. While some of the bonus FAR options may not recoup their cost, TDR options are even less likely to directly add value exclusively to a receiving site because the community benefit generated at a TDR sending site is often not close to the receiving site.

As of March 2021, Section 33.510.205 of the Central City Plan District prioritizes options by specifying which bonus and transfer options must be used before others. For example, the first tier of 3:1 FAR bonus must come from inclusionary housing, affordable housing, historic landmark transfers or riverfront open space. There are some exceptions to this prioritization requirement. For example, the South Waterfront subdistrict is exempt from this prioritization, but for certain projects in target areas, the South Waterfront Willamette River Greenway bonus option must be used before any other bonus. 

After the first 3:1 FAR of bonus, projects can use other bonus floor area options: the inclusionary housing bonus option, the Affordable Housing Fund bonus option, the riverfront open space bonus option, the South Waterfront Willamette River Greenway bonus option, South Waterfront open space bonus option, and payment to the SWPOSF. Portland distinguishes the bonus options from its transfer options even though the public benefit from a bonus option might occur offsite, an outcome that in many other jurisdictions would be characterized as a form of transfer rather than a bonus, which typically means allowing added development potential to a project in return for a public benefit provided at that project site. 

Importantly, the code as it existed in March 2021 listed six FAR bonus options rather than the 18 options available in 2007. This suggests that Portland responded to the Johnson-Gardner study by limiting bonus FAR to achieve community benefits that were most important and/or in the greatest need of incentivizing. As detailed below, the code in March 2021 requires certain developments to provide locker rooms and eco roofs without getting an FAR bonus in return. In addition to requiring rather than incentivizing locker rooms and eco roofs, this change eliminates the two ways of gaining bonus FAR that were cheaper than the average cost of transferring FAR.  

As of March 2021, the Central City transfer options at 33.510.205.D do not limit the amount of floor area that can be transferred to a receiving site as long as the sending site retains the minimum FAR required by the code or an amount equal to the total surface parking area multiplied by the maximum allowed floor area, whichever is more. Two transfer options are discussed in this code section.

Historic Resource Transfer Option – Potential sending sites consist of Landmarks or contributing resources in a historic or conservation district that are zoned RM3, RM4, RX, CX, EX or OS. Sending site owners who choose to participate must enter into an agreement to bring the structure up to seismic standards if it is not already compliant and enter into a covenant prohibiting the demolition or removal of the structure unless approved by the city. Qualified sending sites can transfer their unused FAR plus an extra 3:1 FAR. The receiving sites must be zoned RM3, RM4, RX, CX or EX and located within the Central City but outside the South Waterfront subdistrict. However, there are exceptions to transfer FAR outside the Central City if certain standards are met. 

Transfer of Floor Area Within a Floor Area Transfer Sector – Floor area in the RX, CX, EX, and OS zones, including bonus floor area, can be transferred to any receiving site within the same floor area transfer sector as established by Map 510-23. The sending site cannot be a landmark or a contributing resource in a historic or conservation district. If bonus floor area is included in the transfer, the community benefit must be completed before the receiving site can be issued an occupancy permit.

As of March 2021, Section 33.510.243 mandated all buildings of 20,000 square feet or more in three zones to provide eco-roofs as a requirement rather than as a way to achieve bonus density. Similarly, as the code existed in March 2021, in the South Waterfront sub-district, additions of at least 100,000 square feet of non-residential floor area had to, with some exceptions, provide locker rooms with showers, dressing areas, and lockers available to all building tenants without getting bonus FAR in return.          


Johnson-Gardner. 2007. Evaluation of Entitlement Bonus and Transfer Programs: Portland’s Central City. Accessed 2-27-21 at Microsoft Word – Bonus Study Report draft (oregonlive.com)