TREES ON BUILDING SITES

WHY TREES?

Trees are good for our health, and for the health of the planet. They can slow down wind and reduce heating bills; give shade and reduce the risk of skin cancer; absorb pollution, especially carbon dioxide, and so reduce global warming; stabilise sloping sites; catch rainfall, slow down water runoff and reduce the risk of flooding and landslip; and muffle noise.

Trees may also provide sustainable crops of timber, other craft materials, fuel, and food. Trees can give shelter and food for other wildlife, especially if they form “green corridors” connecting the site to other trees and woods.

Trees are beautiful and will give pleasure to the people who will live and work on the site, and to the people around. They may help to sell the development.

But you should not necessarily keep all existing trees. Trees grow, and you need to think ahead to avoid direct and indirect damage to new buildings. Some trees may be unsafe, and to make the site suitable for building you may need to remove them or have tree surgery done to make them safe. If potentially hazardous trees are left on site, purchasers might be able to claim for damage or for necessary tree surgery.

Building works can easily damage trees, especially the roots, and trees may then die back and become unsafe. You need to know before even designing the site which trees to keep and how to protect them.

This leaflet is a basic outline of the process you should follow. It will help you to satisfy planning conditions and to comply with Tree Preservation Orders. The advice is based mainly on guidance in DoE Circular 36/78, DETR guidance on Tree Preservation Orders, and British Standard 5837.

PRE-APPLICATION ADVICE

Contact the Isle of Wight Council for an informal discussion if you want advice on the precise information you will need to provide before submitting your application. Relevant sections will include Development Control, Countryside, and Building Control. Check whether any trees on your site or adjoining sites are protected.

TREES AND CLAY SOILS

Heave and shrinkage of clay soils caused by changes in moisture content can cause structural damage to buildings, and may be made worse by trees close to buildings. Foundation design on such soils must take account of existing trees, and proposed new planting - contact Building Control for further information.

TREE SURVEY AND SITE DESIGN

If there are trees on or next to your site, you should submit a tree survey as part of your planning application. This will include the following work:

Plot each tree trunk, and the spread of the canopy, to within 1m; and the existing ground level at the base of the trunk, to within 0.1m.
Survey the trees, their condition, their landscape potential, and necessary surgery.
Use tree survey to help decide site layout, tree retention, and new planting.

You are advised to employ a level surveyor, tree consultant and landscape architect to ensure good quality survey and design.

PLANNING APPLICATION - TREE SURVEY PLAN

Submit the tree survey as a plan to an appropriate scale (usually 1:200 or 1:500) showing:

individually numbered trees and levels (trees to be removed as dotted lines; trees to be retained as solid lines);
mark any protected tree with its TPO number;
position of protective fencing;
schedule of species, landscape value, diameter at breast height 1.3m (dbh), crown spread, height, health, structural soundness, proposed tree surgery, and reason(s) for any removals.

PLANNING APPLICATION - LANDSCAPE PLAN

Submit landscape proposals as a plan to an appropriate scale (usually 1:100 or 1:200) showing:

existing and proposed levels (with sections as necessary);
positions and depths of buildings and foundations, paved surfaces, drainage (surface and foul), and services (water, gas, electricity, telecommunications);
trees to be retained, numbered as on the tree survey, and position(s) of protective fencing;
new planting - this should respect (but not necessarily imitate) the existing trees on and around site, if these are sound, attractive and appropriate.

All trees should be chosen to fit the site and the space available. Propose indigenous native trees only if you plan to use local provenance stock. Do not plant trees too close to buildings on clay soils - contact Building Control for advice.

PLANNING CONSENT AND CONDITIONS

If your application is acceptable, you will be given planning permission subject to certain conditions. These will include conditions to retain and protect any trees which the local planning authority consider are worth retaining. Trees to be retained will usually be protected by Tree Preservation Orders as well.

ON SITE - COMMENCEMENT - TREE WORK

Notify the Development Control section when you intend to start work on site.
Employ a competent tree contractor to carry out tree work as detailed in the planning application:

remove any trees as necessary;
tree surgery work as necessary (for example, to make trees safe, or improve their shape, or open up views) to trees to be retained.

ON SITE - PROTECTIVE FENCING

Put up protective fencing around trees as detailed on the tree survey and landscape plan. This is to ensure that trees and especially tree roots are not damaged during building. Most tree roots are in the top 60 - 90 cm (2-3') of soil, and extend out at least as far as the edge of the tree’s canopy. The protective fencing should therefore extend out at least as far as the edge of the tree’s outermost branches - see BS 5837:1991 for more details.

ON SITE - CONSTRUCTION WORK

Do not let anybody except the tree contractor onto site until the protective fencing has been put up. It will help to erect warning tape along the entire length of the fence - “TREE PROTECTION AREA - KEEP OUT”. Make sure that all contractors and subcontractors have a copy of the planning consent with the conditions, and a copy of the approved plan (contact the copyright holder) showing the protective fencing. Make sure that anybody who comes on site knows that they are not allowed into the protected area(s). Make sure that the fencing stays up until building is complete, and that nobody enters the area, changes the ground levels inside it, or stores any material there.

ON SITE - NEW PLANTING

Make sure that the ground is left in good condition for planting new trees and other plants. Try to avoid compacting the soil, and relieve any compaction before planting. Rather than importing new topsoil, use topsoil from the site, improving it if necessary with organic matter such as composted green waste. Employ a competent tree or landscape contractor to prepare the ground, supply, plant and maintain new planting.

GUIDELINES FOR THE PLANNING, INSTALLATION AND MAINTENANCE OF UTILITY SERVICES IN PROXIMITY TO TREES.

NJUG 10 is a guide produced and published by the National Joint Utilities Group. It is intended for use by construction teams involved with the actual physical maintenance of services near trees but will also be of use to arboriculturists, architects, builders, engineers, planners and all others involved with the relationship between trees and underground services.

The following subjects are discussed within NJUG10.

How roots are damaged (root system, types of damage, if roots are damaged).
How underground services are damaged (direct damage, root incursion, indirect damage, wind movement of the tree).
How to avoid damage to trees (trench type & design, backfilling).
Additional precautions near trees.
Special considerations when planning services.
Precautions when repairing existing services.
Avoiding chemical damage to trees.
How to avoid damage to services by trees.
Above-ground services.
Legislation and other guidance (statutory framework, other guidelines).

COMPLETION AND MAINTENANCE PERIOD

You will be required by planning conditions to ensure that any new planting is still there five years after completion, so either take responsibility directly by employing a tree / landscape contractor to manage the new planting to ensure it gets established, or make it clear to prospective buyers that this will be their responsibility.

BACKGROUND READING

See publications for details of books available.

USEFUL CONTACTS

See contacts for details.

Page last updated on: 05/11/2008