Thoughtful ADU Design Could Preserve Trees

Half of Portland’s trees lie on private property. With increased housing density and accessory dwelling units, every day we are losing mature, healthy, large-form trees that City code fails to preserve. Yet with careful design and tougher City regulations, many of these trees could be left undisturbed. Here’s one example.

By Ron Minter, May 2020

Our home at 4609 SW 29th Place is nestled in a quiet hillside cul-de-sac of mid-century homes surrounding an enormous 300-year-old heritage Garry oak. Fortunately, the oak is not threatened. But seven mature Douglas-fir trees in our neighborhood are. They are slated to come down, needlessly, when one of the neighbors begins construction on an accessory dwelling unit (ADU).

Our neighborhood has already experienced a severe reduction in tree canopy in just the past two years. In 2018, a new homeowner removed half to two-thirds of the property’s mature trees to make way for a large lawn and extra parking. Last year a neighbor was forced to remove a large portion of large-form conifers due to disease. The loss of a thick stand of tall Douglas-fir trees between our homes and the western skyline affects more than the view. The trees provide partial buffering from the winds of winter storms. They protect our homes from summer heat: as trees have been taken down, our home interior temperatures have risen. The mature landscaping in our yards, accustomed to summer afternoon shade, are starting to show stress from the additional exposure to sun and dry winds. We are nature lovers. We feel strong emotional attachment to the trees around our homes, along with the birds and other creatures that rely on them for shelter.

Living in Southwest Portland we are fortunate to have greater canopy coverage than some other areas of the city. If tree elimination for development is happening here, think about the impact of tree loss in East Portland neighborhoods, where canopy is much more sparse.

ADU Plans

Early this year the property owner behind us applied for a permit with the Bureau of Development Services (BDS) to build an ADU in his backyard. The plan calls for removing an entire cluster of seven 70- to 90-foot Douglas-firs tucked into the northwest corner of the property. Their root systems are intertwined with one another and with another tree on an adjacent property.

The proposed ADU, whose plans I received through BDS, will be “L” shaped, 40 feet in one direction and 30 feet in the other. The unusual design requires 1,200 square feet of open ground for 800 square feet of interior living space, the maximum allowed for a free-standing ADU. Current Portland City tree preservation and building codes create no barriers for this inefficient plan to become a reality.

There is plenty of room for both the 800-square-foot ADU and these trees.

A quick online search reveals many relatively compact ADU floor plans designed with more conventional square or rectangular footprints. Most of them would easily fit within the existing open area in the applicant’s backyard. The ADU could sit within legal setbacks and still be far enough from the existing cluster of trees to allow them to be left standing.

Feeling Blindsided

We’ve known for several years that our neighbor had long-term plans to build something in the backyard as an assisted-living option for family members. We have no objections to the ADU. We’re aware of the shortage of close-in, affordable housing options in this city.

But the City, we are surprised to learn, does not legally require a homeowner building an ADU to notify neighbors of the plan or the process. In April 2020 I learned my neighbor’s intentions through a casual inquiry after noticing through my kitchen window the stakes newly pounded into the ground around the yard. Construction is slated to start this summer. The plan calls for razing the seven Douglas-firs that have provided so many benefits to surrounding neighbors.

Neighborhood Reaction

Because the ADU site plan reveals how easy it would be to design and place the ADU on the site without disturbing the trees, emotion is running high among neighbors about the senselessness of losing more nearby trees.

Much energy has gone into trying to change the plan. Some of the cul-de-sac residents sent a letter to our neighbor formally stating our concerns with further tree loss and asking that he reconsider cutting these down. The neighbor met with all the concerned cul-de-sac residents outside one evening to discuss the matter. But he intends to proceed with construction as planned.

The relationship between the ADU neighbor and others remains difficult. Once BDS issues the building permit, the trees will be gone.

The City must become more thoughtful in its decision-making about development and its effects, especially on trees. To prevent the pointless loss of trees such as our nearby Douglas-firs, the City needs to change its tree-related codes. It should require that neighbors be notified of an ADU application early on, when there’s still a chance for input on the part of residents who will be directly affected by the plan. At this point, our neighbor seems too invested in the plan to revise it.

Further, when the City approves a development plan it should be taking a broader view of how much tree loss has already occurred in an area. Right now, BDS grants permits based solely on an individual private property. The recent loss of other large trees in our vicinity seems to have no bearing on the bureau’s permit-granting decision.

Residents are left to suffer the consequences.

Here’s a September 2020 update to our situation:

On July 9, 2020, the Bureau of Development Services issued the permit to our neighbors for construction of their ADU, per their original plans, which sadly included the removal of the seven large Douglas-fir trees from their property. On August 12, a crew arrived at the construction site; in less than 36 hours all that was left where our majestic stand of trees stood was empty ground and open air. Here’s a video I made documenting what we had and what was taken away from us.

This recent loss, added to BDS’s permit to another neighbor to remove four large Douglas firs and all trees less than 12 inches in diameter at breast height (DBH) over the last three years, has resulted in the decimation of over two-thirds of an acre of mature, large-form tree canopy from our neighborhood. In exchange, the two neighbors together created about 1,500 square feet of living space--a portion going toward expanding an existing single-family home and the rest going toward one ADU.

This doesn’t seem like a fair exchange considering the growing body of evidence on the health, environmental, and economic benefits that large-form trees provide to the community.

It is time to recognize that large urban trees growing in a populated setting are community assets regardless of property lines.

Currently City staff have proposed two amendments to Portland’s tree code, one that lowers the threshold for applying inch-for-inch fees for removing trees from 36 inches DBH to 20 inches. We submitted testimony in favor of this amendment, citing how the changes would have likely saved our neighborhood trees had they been implemented prior to our neighbors applying for their building permits. We cited other opportunities for future revisions. A more sensible approach needs to be applied to the current tree code. We hope that the proposed amendments will pass, that in December the City Council will approve the project scope for a broader overhaul of the tree code, and that substantial code changes will save other communities from the frustration and sadness that our cul-de-sac community has experienced.