Construction of House Extension Adjacent to a Mature Tree
Client:
- L & Q
- Portcullis Global Ltd
Project Type: Tree Safety Management
Services:
- Visual Tree Assessment (VTA)
- Tree Schedule
- Tree Risk Management Report & Plan
Summary:
We was commissioned to provide an arboricultural implication assessment for an extension to an Elizabethan House in Crawley.
The extension encroached on the root protection area of a veteran yew tree. The tree is a particularly special specimen as it is referenced in the Domesday Book dated 1087, so has the potential to be over 1000 years old. The tree still healthy and vigorous in growth, though the stem contains a large cavity. Due to the historical nature of the tree and its outstanding contribution to the landscape every effort was made to protect and enhance the trees growing environment.
The tree still healthy and vigorous in growth, though the stem contains a large cavity. Due to the historical nature of the tree and its outstanding contribution to the landscape every effort was made to protect and enhance the trees growing environment.
The new extension consisted of a single storey construction and is situated close to the tree stem. Non invasive root investigations revealed limited root growth in the location of the new extension. Two existing small extensions were removed to allow for the new construction. The ground beneath these extensions was not suitable for root growth.
Sympathetic construction techniques were recommended which prevented damage to the trees roots and maintained the soil beneath in a suitable condition to allow future root growth and function.
PJC recommended the extension be constructed on narrow diameter bored pile foundations. This negated the need for extensive excavation within the trees rooting area. The design was flexible to allow for movement of the piles if they conflicted with existing roots.
A biodegradable void former (made from reinforced cardboard) was laid around the pile on which the reinforced concrete base was positioned. The void former will decay over time, effectively leaving the foundations and the building suspended above ground level.
An irrigation system was connected to the guttering and directs water underneath the building within the void, improving the rooting environment.
This construction type prevents soil compaction, whilst allowing continued moisture ingress and gaseous diffusion, required for root function.
This sensitive planning application was accepted with the condition that the construction is supervised by a suitably qualified arboriculturalist. PJC Consultancy carried out the supervision and the construction has been carried out without damage to the tree.
