British Standard 5837 recommends that all trees over 75mm in diameter at breast height should be surveyed and plotted. Established hedgerows should also be plotted, particularly if they are on/adjacent to the boundaries of a site and of importance from a screening point of view. Certain large shrubs such as laurels or Magnolias may be of sufficient size and overall significance to merit plotting.
Table summarising BS 5837 method of classifying trees on a development
site. This is a convenient guide to use when surveying trees.
Retention of Trees and Appropriate Distances for Construction
Table 1 of the standard indicates the minimum recommended distance around a tree which should remain undisturbed, which corresponds to the distance at which protective fencing should normally be erected. This distance primarily avoids unacceptable root damage, taking no account of other factors which have a bearing on appropriate distances between trees and construction.
This Summary of Table 1 indicates recommended minimum distances from centre
of tree to protective fencing according to age, vigour and diameter, within
which unacceptable root damage is unlikely to occur
| Minimum Recommended Distances for Protective Fencing Around Trees |
|||
| Tree Age |
Tree Vigour |
Trunk Diameter (mm) |
Minimum Distance (m) |
| Young |
Normal |
<200 |
2.0 |
| 200 - 400 |
3.0 |
||
| >400 |
4.0 |
||
| Young |
Low |
<200 |
3.0 |
| 200 - 400 |
4.5 |
||
| >400 |
6.0 |
||
| Medium |
Normal |
<250 |
3.0 |
| 250 500 |
4.5 |
||
| >500 |
6.0 |
||
| Low |
<250 |
5.0 |
|
| 250 500 |
7.5 |
||
| >500 |
10.0 |
||
| Mature |
Normal |
<350 |
4.0 |
| 350 750 |
6.0 |
||
| >750 |
8.0 |
||
| Mature + |
Low |
<350 |
6.0 |
| 350 750 |
9.0 |
||
| >750 |
12 |
||
Sub categories are listed in Section 5.2 of the Standard
In practice, appropriate distances of buildings from trees are likely to be in excess of the minimum recommended distances specified in Table 1, and in this regard, attention is drawn to Section 6.3 of the Standard.
Sections 7 and 8 of BS 5837 provide information on how damage to trees during construction work may be avoided.
Clause 7.5.5. of BS 5837 states that the distance may be reduced by up to one third on one side if it is deemed acceptable. It is sometimes assumed that the distance may be reduced by one third in the majority of cases, but in practice, it is rarely appropriate for construction involving excavation to occur within the full recommended minimum distance for protective fencing given in Table 1.
Sections 14, 15 and 16 of BS 5837 provide useful guidance on landscape scheme design, implementation and maintenance, and Appendix A gives basic advice on the selection of suitable tree species.
Useful Contacts:
Arboricultural Advisory & Information Service:
01420 22022 / www.treeadviceservice.org.uk
Arboricultural Association:
01794 368717 / www.trees.org.uk
British Standards Institute
020 8996 9001
Department of the Environment, Transport & The Regions
020 7944 3000 / www.detr.gov.uk