A school in Norwich was proposing to extend their existing sixth form building.   There was limited space available to facilitate the new extension due to the layout of the existing infrastructure.  The area allocated for the new extension was positioned close to a very large Wellingtonia / Sequoiadendron giganteum tree, which was designated with a Tree Preservation Order.

 

We were approached by our client to evaluate the possibilities of building the proposed extension without causing damage to the tree.  We initially prepared a tree survey in accordance with BS5837:2012 ‘Trees in relation to design, demolition and construction - recommendations’ to establish the tree constraints.   We then carried out further investigations, including Tree Root Radar scans and air spade excavated inspection pits, to enable us to map a more precise rooting pattern within the proposed construction area.  

 

Due to the restricted space, the Architects were unable to design the extension whilst completely avoiding the root zone of the tree, but the incursion was kept to a minimum.

 

From the information collaborated we produced an Arboricultural Impact Assessment and Method Statement and a Tree Protection Plan to satisfy the Local Planning Authority that the extension could be constructed with minimal detrimental impact on the tree.  The method statement included the use of a pile and beam foundation system and a raised floor base which minimised the need for extensive excavations into the root zone soils.

 

Planning permission was granted and the extension was constructed in full compliance with the Arboricultural Method Statement, and arboricultural site supervision was maintained throughout the construction period.

The building extension was completed without any significant detrimental impact on the tree and the tree now lives on in safe harmony with its new surroundings, as well as continuing to provide its many values and benefits to the surrounding environment.