If the building work proposed requires planning consent, all trees which could potentially be affected by the development (including those off-site) should be assessed by an arboricultural consultant in accordance with British Standard BS5837 Trees in Relation to Construction – Recommendations, and details of this submitted to the Local Planning Authority with the planning application. This assessment will consider tree condition, dimensions, likely retention span (years), and future growth potential, and will inform design in relation to how close you can build to trees. If the tree is to be retained, constraints to be considered are those below ground and above ground. The below-ground constraints are dictated by the root protection area (RPA) the calculation of which is based on the stem diameter; the above ground constraints are dictated by the height and spread of the tree, future growth potential, shading potential and what you are proposing to construct.
If the work proposed does not require planning consent, it is advised that you still have the trees assessed in accordance with BS5837 to inform good design. If your tree is protected by a tree preservation order (TPO) or is located within a conservation area, legislation relating to tree protection overrides that of permitted development rights, and you risk prosecution if protected trees are damaged.
You will require the services of an arboricultural consultant to assist you with these matters.
In spite of what you may read in newspapers or be told by insurance companies, there are no fixed minimum recommended distances that you should plant trees of certain species from buildings.
When choosing a tree or trees to plant, you should give careful consideration to design, in particular how they will fit with their surroundings when they have reached their mature size. Young trees are frequently planted in spaces which are too small to allow them to grow to maturity, and a consequence of this is that they may be disliked as they develop, frequently resulting in heavy pruning or removal. Consequently, it is important to consider the ultimate size of the tree when choosing what and where to plant.
If you live in an area where there is heavy clay soil it is possible that trees in close proximity to buildings may cause structural damage to them by causing soil shrinkage which can lead to downward movement called subsidence. This is rare and cannot easily be predicted and there are many factors which affect it including the nature of the soil, tree characteristics, foundation design and climate. In areas of heavy clay soil where building foundations are known to be shallow this issue should be considered when deciding where to plant trees and how to manage existing trees – further advice should be sought as necessary.