Why Hire an Arborist When Building an Attached Dwelling Unit (ADU) or Tiny Home Near Trees?
Today’s site visit reminded me why people should hire an arborist and why every tree check-up is really about people. The homeowner and her mother wanted to know if it was feasible to build a tiny home in their already tiny backyard, directly beneath a tree that was anything but tiny, a mature American Elm, Ulmus americana. This project came in as a arborist site visit with verbal approval of feasibility, but included something much more poignant and human.
This project to build a tiny home near this tree was very human. The story the duo shared of transition, loss, independence, and love was interwoven around the needs of the tree. The mother was preparing to sell her five-acre rural homestead, a place she and her late husband had lovingly created together. She described how they had logged and milled their own wood to build their home, shaping not just a house but a life of privacy, space, and self-reliance. Now, she was facing the reality of completely downsizing, and of creating a small dwelling in her daughter’s fenced urban backyard. The daughter loved her backyard tree. She was really worried if cutting roots to accommodate construction would kill the tree or not.
As I continued to listen, I realized this project was about tree health and resilience but also about a mother and daughter trying to make space for one another, literally and emotionally.
From the mother’s perspective, the move must feel like giving up so much: her acreage, privacy, history, and autonomy. To leave behind a property built with her husband’s hands, to acknowledge time has passed and cannot return, and to step into a tiny home in her daughter’s small yard were all a profound shift. It is easy to imagine how vulnerable that must feel. Why, she may wonder, does her daughter seem to care more about the tree than about her? She wanted acknowledgement that she was giving up her own special space to live with this tree that she actually really liked too.
As a daughter of an aging mother myself, I could put myself in the daughters place. As I saw it, from the daughter’s perspective, her sacrifice of privacy, and autonomy were also significant. She was sharing her small amount of land behind her modest home, offering up her limited outdoor space, planning to adjust her home life to the construction and her mother’s presence. She was inviting her mother back into close proximity and daily life. Her small backyard would now host a special structure with a shared future, a tiny home with her mother in it. Did the tree, standing at the center of that yard, represent stability, continuity, and more than something valuable? I could sense protecting it was not trivial to her. I briefly wondered if it may be a way of holding onto the past and present while being uncertain of the future. Trees certainly provide permanence when everything else is changing and feels uncertain.
The tension between them was evident, as was their care for one another. I felt honored to stand between them, not as a referee, but as a voice for the tree and a guide toward coexistence. My role was to help them imagine how they and the tree could share the space safely and responsibly. They needed to hire an arborist to speak for the tree as they developed their design.
The tree itself was remarkable. It had previously been misidentified as a type of Maple by another arborist, but I had no doubts about its identity. This was unmistakably an American Elm, which was quite a rare species in Edmonds, Washington. I was confident in my identification because the tree was covered in small red flowers at the time of my visit, and fallen leaves beneath the canopy confirmed the distinct leaf structure. The trunk displayed the classic furrowed, rope-like bark pattern characteristic of mature elms, and the canopy had the iconic, graceful V-shaped form, arching high and wide.
And wide it was. The tree trunk was 40 inches in diameter at standard height, measured at 4.5 feet above the ground. The canopy spread was approximately 80 feet across. The tree posed an enormous presence over the small, fenced urban backyard with neighbors in close proximity on all three sides. The rooting zone consisted largely of lawn, which often means the majority of the tree’s structural and absorbing roots are likely spread broadly and relatively shallowly throughout the yard. Any construction within that space would require careful planning to avoid significant root damage.
The tree had not received consistent, proper structural pruning over the years. As a result, it had experienced branch failures during wind and wet-snow-storm events. While pruning cannot prevent all storm damage, regular maintenance can correct structural weaknesses and reduce the likelihood of failure. In this case, broken branch stubs had resprouted heavily, creating dense clusters of poorly attached shoots. These sprouts often have weak attachment points and can become future hazards if not addressed. Additionally, the tree exhibited codominant stems with a visible crack between the two main trunks.
There were also signs of bacterial wetwood extending up both trunks to approximately 20 feet. While often more of a chronic condition than an immediately fatal one, it does indicate internal stress and can contribute to structural failures.
As a species, American elms carry their own reputational challenges. They are sometimes referred to as “widow makers” because they can shed large branches unexpectedly, even on calm summer days. They are also highly susceptible to Dutch Elm Disease, a fatal fungal infection spread by bark beetles that blocks the tree’s vascular system and can kill a tree rapidly. Given the exceptional stature, preserving this tree is valuable but it poses a real threat to a target underneath through time because of the potential for losing limbs during storms but also on calm summer days, or widow makers.
This project was in the planning phase but hadn’t considered the species characteristics because the tree had been misidentified. The mother and daughter were going to continue planning a design to protect 75% of the critical root zone and adjust foundation design to float over roots in the remaining 25%. I recommended beginning routine maintenance to the canopy prior to building anything underneath to balance and reduce the structure to a good maintenance point, and installing support systems between the two trunks. By listening, I was able to understand their shared vision. With my arboricultural background, I know methods to ensure a successful path forward for this amazing American Elm tree to shelter people who love it.
In the end, this visit reminded me that arboriculture is rarely just about trees. It is about people. It is about our relationship with trees and with our properties, about memories made and the potential of future memories, and change. Trees are a physical manifestation of the slow changes of time.