Leach Botanical Garden Pavilion & Tree Walk

February 4, 2024

The award-winning design for Leach Botanical Garden Pavillion & Tree Walk in Portland, Ore. highlights its Pacific Northwest verdant landscape while increasing mobility access to all visitors. 

Small Project Award
The architecture is deliberately deferential to the landscape, providing a quiet backdrop and flexible gathering space.
Aaron Leitz
  • The architecture is deliberately deferential to the landscape, providing a quiet backdrop and flexible gathering space.
    Aaron Leitz
    The architecture is deliberately deferential to the landscape, providing a quiet backdrop and flexible gathering space.
  • The arbor interior spills onto an exterior stone terrace with integrated gas fireplace, fostering year-round enjoyment.
    Tamra Tiemeyer
    The arbor interior spills onto an exterior stone terrace with integrated gas fireplace, fostering year-round enjoyment.
  • Thirty-four feet above the ground at its highest point, the circular walk weaves through mature trees, hovering above the hillside instead of following the topography.
    Aaron Leitz
    Thirty-four feet above the ground at its highest point, the circular walk weaves through mature trees, hovering above the hillside instead of following the topography.
  • Trails and pathways below provide another perspective of the tree walk, arbor and gardens beyond.
    Tamra Tiemeyer
    Trails and pathways below provide another perspective of the tree walk, arbor and gardens beyond.
  • As the starting and ending point for the tree walk, the arbor and terrace establish a sense of arrival, as well as a spot to linger out of the elements beneath the dramatic cantilevered roof.
    Aaron Leitz
    As the starting and ending point for the tree walk, the arbor and terrace establish a sense of arrival, as well as a spot to linger out of the elements beneath the dramatic cantilevered roof.
  • The architecture is deliberately deferential to the landscape, providing a quiet backdrop and flexible gathering space.
  • The arbor interior spills onto an exterior stone terrace with integrated gas fireplace, fostering year-round enjoyment.
  • Thirty-four feet above the ground at its highest point, the circular walk weaves through mature trees, hovering above the hillside instead of following the topography.
  • Trails and pathways below provide another perspective of the tree walk, arbor and gardens beyond.
  • As the starting and ending point for the tree walk, the arbor and terrace establish a sense of arrival, as well as a spot to linger out of the elements beneath the dramatic cantilevered roof.

Project highlights: Leach Botanical Garden Pavilion and Tree Walk

  • Architecture firm: Olson Kundig
  • Location: Portland, Ore.
  • Category: Three
  • Project site:  Not previously developed
  • Building program type(s):  Public assembly - recreation

  • Portland, Oregon’s Leach Botanical Garden is the former home of devoted botanists John and Lilla Leach, who contributed greatly to the study of native plants in the Pacific Northwest. This project is part of the first phase of a master plan that charts out new buildings, experiences, and site improvements over the 16-acre campus in an effort to enhance visitors’ connections to nature. The project adds a new, unconditioned arbor pavilion and accompanying terrace as well as a meandering elevated tree walk through the garden’s mature trees. 

    Integrated into the lush landscape, the new arbor and fireside terrace provides dedicated space for gathering and hosting special events. Inspired by a type of greenhouse known as a lath house, the arbor is a precise composition of Kebony screens attached to a steel and glulam structure. In eschewing solid walls, the team has ensured plants can grow unabated up to and around the arbor. 

    Throughout the day, the semiconfined space provides protection from the sun and wind while inviting a dynamic play of light and shadow. The arbor’s interior also spills onto the adjacent stone terrace, which includes an integrated gas fireplace to accommodate year-round enjoyment. 

“This project is inclusive for all people and has forged a strong relationship with the ecosystem. It provides the benefits of well-being to any garden visitor. The restraint demonstrated by the design team balances its understanding of the garden’s intent and the architectural elements in a beautiful way.”
Jury Comment

Nearby, the elevated tree walk offers a new experience for exploring the gardens and surrounding forest. Rising to 34 feet above the ground at its highest point, the circular walk hovers above the hillside in lieu of following the topography. Its simple, durable materials allow the walk to fade from view while simultaneously creating a sense of floating through the trees. 

The nonprofit that operates the garden began planning for revitalization in the 1980s and led a multiyear fundraising campaign to make it a reality. The garden can now serve more visitors with enhanced access to parts of the property that were historically difficult for those with mobility issues to traverse—a major goal of the plan. Now, visitors of all ages and abilities can engage with nature and enjoy the full garden experience without taking a strenuous hike. 

Framework for Design Excellence

Was there a design charrette? Yes

Level of community engagement:

Collaborate: A partnership is formed with stakeholders to share in the decision-making process including development of alternatives and identification of the preferred solution. 

Site area that supported vegetation (landscape or green roof) pre-development: 100%

Site area that supports vegetation post-development: 75%

Site area covered by native plants supporting native or migratory species and pollinators: 75%

Strategies used to promote Design for Ecosystems: Biodiversity, Bird safety, Soil conservation, Habitat conservation, flora/fauna, Abatement of specific regional environmental concerns 

Is potable water used for irrigation? Yes

Is potable water used for cooling? No

Is grey/blackwater reused on-site? No

Is rainwater collected on-site? Yes

Stormwater managed on-site:  unknown

2030 Commitment baseline EUI:  0 kBtu/sf/yr

Predicted net EUI including on-site renewables: 0  kBtu/sf/yr

Reduction from the benchmark:  Unknown

Is the project all-electric? No

Level of air filters installed: Not applicable

Was a “chemicals of concern” list used to inform material selection?  Yes

Do greater than 90% of occupied spaces have a direct view to the outdoors? Yes 

Were embodied carbon emissions estimated for this project? No 

Estimated service life: 100 years

Floor area, if any, representing adapting existing buildings:  0%

Ability to survive without utility power:  Passive survivability

Risk assessment and resilience services provided: Unknown

Has a post-occupancy evaluation been conducted? No, and a POE will not be conducted.

Building performance transparency steps taken:

Present the design, outcomes, and/or lessons learned to the office.

Present the design, outcomes, and/or lessons learned to the profession.

Present the design, outcomes, and/or lessons learned to the public. 

Project Team and Jury

Year of substantial project completion: 2021

Gross conditioned floor area: 0 sq. ft.

Lead Consultant, Landscape Architect & Master Planning: Land Morphology  

Architect: Olson Kundig 

Design Principal: Kevin Kudo-King, AIA, LEED AP 

Project Architect:  Misun Chung Gerrick  

Architectural Staff: Michael Wright

General Contractor: JW Fowler 

Civil Engineer: Janet Turner Engineering 

Structural Engineer: Lund Opsahl Electrical 

Electrical Engineer & Lighting Design: Reyes Engineering 

Green Infrastructure: GreenWorks 

Traffic Engineer: Lancaster Engineering 

Land Use Planning: Winterbrook Planning 

Specifications: Friday Group 

Cost Estimating: Mitali & Associates

Andre Johnson, AIA, Chair, AJA, Raleigh, N.C. 

Mindy Aust, AIA, MA Architecture, Des Moines, Iowa

Joy Cunningham, Assoc. AIA, MG2, McLean, Va.

Lisa Sauve, AIA, Synecdoche, Ann Arbor, Mich.

Matt Seltzer, AIA, archimania, Memphis, Tenn.

Small Project Award

AIA and its Small Project Design (SPD) Knowledge Community present the annual Small Project Award Program to raise public awareness of the value and design excellence that architects provide regardless of the limits of size and budget. 

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Winners: Small Project Award 2024

Nine projects showcase the best small project design and the big impact small projects can have on people and communities.

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