In April 2012 the revised BS 5837: 2012 ‘Trees in relation to design, demolition and construction – Recommendations’ came into practice. The British Standard provides guidance in respect of trees on development sites.
When conducting the tree survey onsite the arboriculturalist will make decisions on which trees are to be retained by looking at the condition of the tree and the potential is has grow and develop healthily. Useful questions to ask as part of a tree inspection are: does the tree have any structural defects? Is it significantly contributing to the amenity of the area? Are there any signs of early disease? What is the estimated remaining lifespan of the tree?
Information will also be collected on the spatial dimensions of the tree such as stem diameter, height and crown spread. The tree survey data can then be used to inform design stages and establish methods for tree protection during the demolition and construction phases of the project based on which trees are marked for retention.
If trees are to be retained, constraints to be considered are both above and below ground. The root protection area (RPA) is the constraint below ground, this is the area in which the tree has established its root network and must be protected throughout development. The constraints above ground are dictated by the height and spread of the tree, future growth potential, shading potential and what you are proposing to construct. This applies to planning applications for most developments.
If the work you are proposing does not involve Local Planning Authority (LPA) consent it is advised that surveys be carried out as described in BS5837 to inform good design practice.
If your trees are subject to Tree Preservation Orders (TPOs), or are within a conservation area the legislation that covers protected trees overrides any permitted development rights. Work carried out without consent from the LPA can lead to prosecution.