Annex B Trees On or Adjacent to Development Sites
B.1 This Annex provides further detailed technical information to assist implementation of Policies relating to trees. Paragraphs 11.73 to 11.79 and Policy NE 21 ‘Trees and Development Sites’ in Section 11 on the Natural Environment and the Countryside concern trees on or adjacent to development sites.
B.2 SUBMISSION OF A TREE SURVEY
The need for a tree survey is stated in paragraph 11.75. The matters this survey should include are set out below:
- an accurate site survey including ground levels and existing features;
- the location, species, canopy size, and likely root system spread of all trees on and adjacent to the site;
- a tree condition survey;
- an assessment of the ecological value of the trees;
- an arboricultural implications study;
- a hedgerow survey (where relevant);
- fill levels plus cut and fill details;
- service and drainage details;
- the location of site compound, storage areas and temporary access where relevant;
- details of measures to be taken to protect trees during construction; and
- the internal layout of dwellings where relevant.
B.3 SHADE CAST
Paragraphs 11.78 to 11.79 explain the need to take account of shade cast if future pressure to fell or prune trees is to be avoided. The Council will take into consideration the following factors when assessing the degree of shade cast and how close to an existing tree(s) a new building will be permitted:
- the location of the building in relation to the tree(s). The assessment needed to establish whether or not a building would be subject to shade cast is achieved by taking a 45 degree angle from the average attainable height of the species of tree (as stated in Table B 1) to the ground level in the sector between the north-east and north-west of the tree(s). Any window and associated room falling within that zone would be subject to shade cast. Residential proposals are particularly susceptible to shade cast. Therefore, where windows to habitable rooms of dwellings would lie in the sector between the north-east and north-west of a tree, a minimum distance equivalent to the average attainable height of the tree will be required (subject to allowance being made for the spread of the tree’s crown and site features such as slope and aspect). Where the minimum distance cannot be achieved the dwelling would be subject to an unacceptable level of shade cast and is therefore not likely to be acceptable;
- the type of building (for example, more light will be needed in a house than an industrial unit);
- the tree(s) species and average attainable height;
- the aspect of the tree from the proposed building (for example, a tree on the northside of a building will take less light from a building than one on the southside);
- the topography of the site (for example, a tree located at a lower level than a building will generally take less light from it than one located at a higher level than it);
- potential post development nuisance problems. Consideration will be given to the likelihood of future requests to fell and prune trees that may cause a nuisance through, for example, interference with TV reception and leaf litter in gutters.
- in residential proposals gardens can also be subjected to shade cast which can be particularly disliked in private south facing gardens, thus increasing the likely pressure from future residents to request felling of the appropriate trees. The likely shade cast effects on private garden areas of development proposals will also be taken into account.
Table B.1 lists the likely attainable heights of a variety of trees commonly found in the District. The maximum attainable height would only be achieved in good conditions and on open ground. As these conditions are not always prevalent in the District a more realistic average attainable height of trees is calculated by averaging the height at 20 years together with the maximum attainable height. It is this average attainable height that will be used to establish the level of shade cast. The list includes most trees likely to be encountered on development sites and those suitable for planting in residential areas. There are many other species and cultivars, too numerous to list here, some of which would be acceptable depending on location. Inclusion in the list does not imply suitability for a particular situation. Information concerning the average attainable height of trees that do not appear on the list can be sought from the Council’s Community Services Trees Officer.
| TREE TYPE | Average Height at 10 years (metres) | Average Height at 20 years (metres) | Maximum Attainable Height (metres) (in good conditions and on open ground) |
Average Attainable Height (metres) |
| ASH (Common) |
8 |
11 |
35 |
23 |
| ALDER (Common) |
8 |
15 |
25 |
20 |
| BEECH (Common) |
6 |
10 |
40 |
25 |
| BIRCH (Silver) |
8 |
18 |
26 |
22 |
| CEDAR (Deodar) |
8 |
12 |
36 |
24 |
| DOGWOOD (Pacific) |
3 |
6 |
12 |
9 |
| DOUGLAS FIR |
9 |
17 |
59 |
38 |
| ELM (Wych) |
8 |
15 |
38 |
27 |
| HAWTHORN |
4 |
6 |
15 |
11 |
| HAZEL (Common) |
4 |
6 |
8 |
7 |
| HOLLY |
4 |
6 |
20 |
13 |
| HORNBEAM |
7 |
11 |
20 |
16 |
| HORSE CHESTNUT |
8 |
11 |
38 |
25 |
| LARCH (European) |
8 |
15 |
43 |
29 |
| LIME (Common) |
8 |
11 |
46 |
29 |
| MAPLE (Norway) |
8 |
13 |
28 |
15 |
| OAK (Common) |
6 |
11 |
26 |
19 |
| PINE (Scots) |
8 |
12 |
36 |
24 |
| POPLAR (Lombardy) |
10 |
17 |
36 |
27 |
| ROBINIA |
9 |
15 |
30 |
23 |
| ROWAN |
8 |
12 |
18 |
15 |
| SPRUCE (Norway) |
8 |
15 |
44 |
30 |
| SYCAMORE |
10 |
15 |
35 |
25 |
| WALNUT (Common) |
5 |
12 |
30 |
21 |
| WHITEBEAM |
5 |
9 |
20 |
15 |
| WILD CHERRY |
8 |
14 |
30 |
22 |
| WILLOW (Crack) |
10 |
15 |
25 |
20 |
Source : ‘The Trees of Britain and Northern Europe’ A. Mitchell, J Wilkinson (1982) Collins, London.
Examples of Shade Cast Assessment in Residential Development Proposals
Picture B.1 Shade Cast
Picture B.2 Shade Cast