Trees on Development Sites
Trees on development sites may be protected by Tree Preservation Orders (TPOs) and/or by conditions attached to a planning permission. It is important that such trees are properly protected during construction.
What conditions can be attached to a planning permission to protect trees?
For any work being carried out close to a tree, the Council requires such work to be undertaken in accordance with British Standard ( BS 5837:2012 - Trees and Construction). An additional condition may be attached to a planning permission requiring the approval of design of the building's foundations and layout to ensure that the work does not affect the trees or tree roots on the site. We would normally attach conditions that require applicants to protect trees (including roots) during construction and for a period of time after completion of the development or replace trees in the event of damage.
Does a TPO prevent development of a site?
A planning application may be refused if it would result in the loss of a tree or trees that provide significant amenity value to the local environment. We consider the impact of development proposals on trees when we assess planning applications.
Is a TPO application required for works to trees on development sites?
The Council's consent is not required for cutting down or carrying out work on trees if this is needed to implement a planning permission. A TPO is overridden if a tree has to be felled to make way for a new building for which full planning permission has been granted. However, developers should be mindful of any conditions attached to the planning permission in respect of existing and replacement trees. Where development is being carried out with permitted development rights, that is, when planning permission is not needed, for example, for a domestic extension or for a structure in a garden permission would still be required to cut down or carry out work to a protected tree which may be affected by the development.
What steps can be taken to preserve and protect trees when construction work is to take place close to them?
The following guidelines are designed to help developers protect the surrounding trees during construction:
Protecting Tree Roots
Tree roots keep a tree healthy and upright. Most roots are found in the top 600mm of soil. They often grow out further than the tree's height. The majority of these roots are very fine, even close to a tree few will be thicker than a pencil. Most street tree roots grow under the pavement and into front gardens, but they can also grow under the carriageway. If roots are damaged, for example by trenching, the tree may fall or lose its vigour and decline.
- Establish a protection area around each tree. To determine the root protection area, measure the stem diameter of a tree at 1.5 metres above ground level and multiply this by 12 and draw a circle of this radius from the centre of the tree.
- Erect Heras fencing on scaffolding poles around the protection zone, as recommended in BS5837:2005.
- Seek advice from a supervisor or one of the council's tree officers when you are unsure of requirements.
- Report all tree damage to the site supervisor. • Hand dig within the identified protection zone of any tree and carefully work around roots, retaining as many as possible.
- Consider using an airspade as this is a non-invasive method.
- Use sharp cutting/pruning tools when roots need to be cut and only cut those roots measuring less than 25mm in diameter. Make a clean cut and leave as small a wound as possible. Any work to roots with a greater diameter requires consent from the council.
- Reinstate around the exposed tree roots with sand and reinstate tree pits with good quality top soil. • Keep compaction to a minimum in the immediate tree root area.
Actions to Avoid:
- Never excavate with machinery within the root protection zone. Use trenchless techniques where possible. Otherwise dig only by hand.
- Never cut roots over 25mm in diameter, unless the Council's tree officer agrees beforehand.
- Never repeatedly move/use heavy mechanical plant close to trees except on hard standing.
- Never store spoil or building material, including chemicals and fuel, near to trees.
- Never light a fire near a tree.
- Never chain machinery to trees, or nail notices to their trunks or lean paving slabs against trees.
Important note: Frost can damage exposed roots. If trenches are top be left open overnight, cover the roots with dry sacking, and remember to remove the sacking before backfilling