All trees should be protected during construction work in accordance with British Standard 5837:2012

Forest at Učka mountain range

Trees are a vital part of our ecosystem; they provide oxygen, contribute to urban cooling and produce micro-climatic effects that can reduce energy demands in buildings. They are extremely beneficial to our environment, for many different factors including keeping our air clean, fighting soil erosion and helping to control noise pollution. Despite this, trees often suffer the indirect consequences of careless construction work.

In this blog, we will look at tree protection zones and how to carry out construction work whilst complying with the British Standard that protects trees.

 

Trees in relation to design, demolition and construction (BS 5837:2012)

All trees should be protected in accordance with Trees in relation to design, demolition and construction (BS 5837:2012). The good practice recommended in this British Standard is intended to assist the objective to achieve a sustainable, harmonious relationship between trees and structures. BS 5837:2012 follows a sequence of events, with tree care at the core of the process.

The key requirements are as follows.

Tree Protection Zones

The roots of a tree help to keep it healthy and upright. Roots tend to be found in the top 600mm of soil and usually grow out further than the trees height. If roots are damaged this can cause irreversible harm and could lead to the trees death.

There are zones surrounding a tree where certain rules apply to help prevent damage to roots.

 

 

tree protection

  1. Prohibited Zone

The prohibited zone is located one metre away from the trunk (red line on the above diagram). Unless a full consideration with the Local Authority tree officer has occurred, no excavations can be carried out in the prohibited zone.

You are also not able to store materials, plant and spoil in this zone.

  1. Precautionary Zone

The precautionary zone is four times the tree circumference (yellow line on the above diagram). If excavations must be taken out in this zone, use of mechanical excavation is not allowed. If there are any exposed roots, then precautions must be taken to protect them.

You are also not able to store materials, plant and spoil in this zone.

  1. Permitted Zone

This is any area further than the precautionary zone. Excavation work can be carried out in this zone, but with caution and limited use of mechanical plant. Again, any exposed roots in this zone should still be protected.

 

Additional Control Measures

The British Standard also recommends that the following practices should be followed when construction work is being carried out to protect trees:

  • Protected Zones – a fenced off area around the tree should be established to eliminate damage during construction. This area should be fenced off and the rules for each zone must be followed.
  • Avoid Compaction of Soil – Soil compaction destroys the soils pore structure, making it hard for trees to uptake water. This can be caused by storage of equipment or using area as a thoroughfare.
  • Considered Excavation – when excavating for foundations and utilities, the welfare of root systems must be considered. The closer the excavation is to a tree, the more likely the chance of damage.
  • Ground level change – root locations should be acknowledged. Increases in ground level could cause compaction, consequently suffocating shallower roots. Reduction in ground level can cause severance of roots and altered drainage rates, affecting water availability.
  • Machinery Impact – torn branches, damaged bark and wounds to the trunk can lead to decay and disease of the tree.
  • Contamination of soil – leakage of chemicals from construction materials needs to be avoided through correct storage. The storage of such substances must not be kept within the protection zone and should be downhill from the tree.

 

In next weeks blog we are going to look at Tree Preservation Orders and how to gain permission to work on, prune or remove a tree which is protected

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