Training updates for the planning and construction professions

It recognizes that there can be problems of development close to existing trees which are to be retained, and of planting trees close to existing structures. The standard sets out to assist those concerned with trees in relation to construction to form balanced judgements. Where development, including demolition, is to occur, the standard provides guidance on how to decide which trees are appropriate for retention, on the means of protecting these trees during development, including demolition and construction work, and on the means of incorporating trees into the developed landscape.

Trees can occupy a substantial part of a development site and because of their potential size can have a major influence on the planning and use of the site. Existing trees of good quality and value can greatly enhance new development, such as by providing an immediate appearance of maturity. However, trees can also be a constraint. Layouts sited poorly in relation to retained trees, future occupiers may resent the retention of trees of an inappropriate size or species, and no amount of legal protection will ensure their retention and survival. To avoid such problems and to ensure a harmonious relationship between trees and structures, careful planning and expert advice is needed on their juxtaposition.

A tree may take a century to reach maturity but it can be damaged or felled in a few minutes. Such damage is frequently caused unwittingly because of failure to appreciate the vulnerability of trees, particularly the root system, and how easily and often insidiously they can be damaged. Irreparable damage is frequently done to existing trees in the first few days of a contractor's occupation of a site. The early erection of tree protection to form the construction exclusion zone before works commence on site is essential as the only way to prevent damage being caused to retained trees by operations in their vicinity.

This British Standard provides guidance for a balanced approach on deciding which trees are appropriate for retention, on the effect of trees on design considerations and on the means of protecting these trees during development. This involves a logical sequence of events summarized as a flow diagram (see Figure 1 below) that has tree care at the centre of the process. Pre planning site discussions involving all parties are recommended.

Tree constraints plan to assist the design process

An accurately measured land survey (also known as a topographical survey) should be undertaken showing all relevant existing site features. Where trees are present, clearance of vegetation to facilitate the survey process should be undertaken only if strictly necessary and with care using hand held machinery. Mechanized flails may be used in more open areas, although bulldozing or soil stripping should be avoided.

This survey should be made available as scale drawings and in a commonly agreed digital format, if available, before any application for planning permission is submitted. Computer-based drawing software should be used where possible.

The land survey should include:

a)   the location of all trees, shrub masses, hedges etc.

b)   other relevant features, such as streams, buildings and other structures, boundary features, trenching scars near to trees and services including drainage runs;

c)    spot heights of ground level throughout the site, as a basis for avoiding changes in soil level around retained trees;

d)   the approximate location of trees on land adjacent to the development site, that might influence the site or might be important as part of the local landscape character.

Just Kidding this wall replaced an existing wall.

The role of the arboriculturist has taken on a new responsibility to work with the ‘development team’ from the outset of planning and development enabling constraints posed by the trees to be identified early.

Our training can provide your team with right information and knowledge to ensure that: