Tree or building part 2
By
Tree or Building: Why can’t we have both?
By Gary Winn Architect, Arboriculturist, and a Professional Member of the Consulting Arborist Society
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When I first posed this question in October 2018, I suggested that the question too often arises from proposals for devel-opment sites, and is also seldom asked. Since then my doctorate has developed to include this question within the re-search title, with a view to advancing the British Architectural profession.
During my training and professional practice as an architect, trees were a mystery, a surprise considering that they exist everywhere and regularly on development sites. My architectural philosophy is based on the natural environment informing built form and so it was a natural progression to learn more about trees and I embarked on the Tech. Cert. in arboriculture course in 2008. Since gaining some knowledge and understanding of a tree’s requirements to function and develop to ma-turity, my work as an architect has evolved to use trees as a source of inspiration and site context for my building designs.
The prompt for commencing the Tech. Cert. course followed a conversation that I had with the late Rodney Helliwell, the arboricultural consultant that the practice worked with at the time. We had been commissioned to design a building on a canal bank that was full of trees and with some protected by preservation order. The conversation that ensued was con-sistent with:
1. Arboriculturist - It is not possible to place the building on the edge of the canal bank as excavation works could under-mine the structural integrity of the bank by disturbing the tree root system that it depended on.
Architect - If a foundation system with minimal excavation could be used, could this enable construction in this position?
Answer - Maybe.
2. Arboriculturist - It won't be possible to locate the floor of your proposal on the ground next to the canal bank as the system of tree roots require essential access to oxygen through a porous surface, and any solid floor on the land would compact the soil and prevent access to oxygen.
Architect - If I could devise a technical solution that located the floor on the canal bank, but prevented compaction, could that work?
Answer - Maybe.
3. Arboriculturist - You cannot build a wall to enclose your building at the canal bank location as the outline profile of the legally protected tree canopies undulates and is not flat like a wall.
Architect - If I were able to create a wall shaped to follow a forecasted canopy outline, could that work?
Answer - Maybe.
The meeting continued in a similar vein, concluding with the agreement that I would design potential solutions to the issues for Rodney to consider as follows:
1. Drill a series of holes along the canal bank around 3m deep and at 3m centres, producing minimal potential disturbance to the structural tree root system. A concrete piling system was proposed to support the perimeter of the buildings exter-nal envelope, allowing the existing root system to intertwine amongst the piles.
1. Response: This would satisfy the biological requirements of the tree roots and subject to a structural engineers input would be a satisfactory outcome.
2. If I raised the floor above ground level, say 600mm would that prevent compaction of the surrounding soil and allow oxy-gen to flow under the ground floor of the proposed building providing adequate access to oxygen?
2. Response: That would be a satisfactory outcome and enable the biological requirements of the tree to function. Howev-er, the external landscaping around the building would also need to be a porous material such as gravel.
3. If I made my wall the shape of the outline of the canopy, with concave balcony spaces to allow the canopy to be undis-turbed could that work?
3. Response: It could work, but the canopy would still require some pruning in the future as it grew, but this would repre-sent good arboricultural management and would be permitted subject to a planning application.
The conversation and subsequent outcomes enabled the trees and building to exist in harmony and is close to completion.
The canal bank project has enabled other members of the practice to understand tree requirements and creatively chal-lenge distance separation specified in regulatory documents and this has resulted in creative and innovative design solu-tions.
The second project example is for a single dwelling under paragraph 79 of the National Planning Policy Framework, which allows development in green belt but , ‘must be truly outstanding or innovative, whilst significantly enhancing its immediate setting’. The design proposals require the support of a review panel and between 2012 and 2018, only 66 planning ap-provals had been nationally approved.
The historical context of the project site is a former ancient forest, and the site and immediate surroundings have mother oaks and saplings which we believe were propagated by jays. The initial site analysis involved visiting local woods, remnant of the original ancient forest, producing the design concept of a glade., with rooms looking into it whilst benefiting from close contact with nature and natural light admittance into the heart of the plan. The visit produced an excitement of the space between the stems of the trees and the space between the forest floor and the underside of the canopy and the different ways that light entered the canopy and made contact with the floor of the forest. We played with the spaces, plotting them and this informed the emergence of a building.
The structure of the trees evoked a feeling of space akin to that in fine examples of architecture.
The site has its mother oaks located at the south eastern part of the site and as we wanted to make a contribution to the site’s landscape we felt that the building should become a link between the mother oaks and the saplings.
The building is supported by helical piles, inspired by the way that tree stems interface the ground, with the precise loca-tions considered following a radar image survey. As with the canal bank project, the ground floor level is raised but with a ‘glade’ represented at the centre of the building. The glade is open to the elements and has a new tree of vertical habit within it. The glade is enclosed by glass to allow views out to nature and natural light in.
Both projects have been excellent examples to demonstrate how technical data processed through a creative thought pro-cess can achieve close proximity between trees and buildings and innovation in design. Of course, this couldn’t happen without a client that believes in such an approach and we have been blessed with the patience and enthusiasm of those who appoint us and the trust that they place in developing challenging approaches.
I complete this article with the same message as the first, believing that architects and arboriculturists, working together, can achieve extraordinary things. The exchange of knowledge between the two professions is vital to allow architects and arboriculturists to work towards the creation of an overall architecture and my current research focusses on how arboricultural knowledge can be introduced to the architectural profession.
To make contact: gary@progressionarchitects.com
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