Home
My Geoworks

Our Solutions

Tree root protection

Trees are a valuable natural resource. They give us clean air, shade, food, raw materials and medicines. They provide natural habitats for insects, birds and animals. Trees are critical in maintaining the ecosystems we all rely on.

Trees

ProtectaWeb is ideal for building roads, car parks, lorry parks, and pathways over the root protection area of existing tree roots. It can be designed to accommodate all types of vehicle loadings and soils without any digging required. The system is simply placed on the existing ground, filled and finished with a porous surface.

The cells are filled with a clean angular stone which allows drainage and aeration through the cells. Two key components of the ProtectaWeb system are the special grading of the stone and the selection of the geotextile separator, placed below the ProtectaWeb.

How are trees damaged during construction activities?

  • Poorly defined and implemented tree works
  • Insufficient tree protection fencing and ground protection
  • Unauthorised or unsupervised excavations for service trenches
  • Storage of heavy materials within the root protection area
  • Compaction of sub-soils due to construction activities
  • Contamination of tree root zones by concrete washings, oils or diesel spills, chemicals or tarmacadam
  • Waterlogging of sub-soils

Supporting healthy trees on construction sites

Where tree retention is specified on development sites, the objective is to achieve a successful relationship between the trees and the newly constructed environment. Retained trees can add a certain maturity and quality to freshly developed areas, enhancing the space for years to come.

The latest guidance includes good practice which is intended to help the landowner or developer and the local authority achieve this goal. It applies even if planning permission is not required.

As part of the survey and reporting process, carried out by a qualified arboricultural consultant, individual trees or copse of trees may be singled out to be retained. ProtectaWeb can work to support established retained trees or new tree growth.

LOCAL AUTHORITY ADOPTION

Three-dimensional cellular confinement systems have been used to protect tree roots from soil compaction since the 1990’s and more and more projects are being adopted by local authorities within their highways and pathways

Trees

Gallery

Urban trees
Understanding the standards

BS 5837 - Trees in Relation to Design, Demolition and Construction

B0S 5837 provides strong, explanatory guidance on tree care, carefully outlining best practices for every aspect of the development. Revised in 2012, the latest standard introduced the following changes:

  • Refers to current planning practices for the management, protection and planting of trees near structures, and for the protection of structures near trees
  • Updated building regulations guidance
  • Recognises the positive contribution trees make towards slowing climate change

How damage is caused to trees during construction

Soil compaction is the biggest threat to existing trees on development sites. Soil compaction forces air, minerals and water particles out of the soil leaving the tree root starved of the vital components needed for health.

Compaction is caused primarily from the construction process or creating new paths, car parks or roadways above the root protection area of existing trees.

This is usually compounded by site traffic using the site prior to any tree protection measures being in place. Other factors can include:

Storing building materials above the root protection area

Creating impermeable surfaces above tree roots

Raising ground levels above the root protection area

Poor design of tree protection measures

Root severance and disturbance during tree works

Building too close to tree trunks

ProtectaWeb tree root protection system is fully compliant with BS 5837:2012 section 7.4.2 Note 1 and accomplishes the following objectives:

  • Offers a no-dig solution with no mechanical damage to the existing tree roots
  • Provides a stable running surface for the required road and vehicle loadings
  • Delivers significant reduction in the loads transferred from above to the tree roots
  • Prevents harmful compaction of the soils in the root protection area
  • Provides a porous, flexible structure to protect the tree’s essential supply of water and oxygen
  • Eliminates the risk of a potential fine for causing damage to or demise of a tree subject to a Tree Preservation Order
  • Long term performance for 75 years
  • CE marked
  • Available in 75mm, 100mm, 150mm & 200mm depths

Attention

If developers or contractors are found to have cut down or damaged trees subject to TPOs they may be prosecuted and fined up to £20,000 per tree. To avoid this, trees subject to TPOs must be managed in accordance with BS 5837:2012 (Trees in relation to construction) and Arboricultural Practice Note 12 (APN 12).

How ProtectaWeb protects tree roots

Without ProtectaWeb tree root protection

Tree dying

 

Lack of tree root protection can lead to:

  1. Rutting and compaction of soil
  2. Physical root damage from wheels
  3. Restricted oxygen and water channels to root system
  4. Roots exposed to contamination from vehicle leaks of oil, petrol and diesel
  5. Root dieback
  6. Overall decline of tree

With ProtectaWeb tree root protection

Tree thiriving

 

ProtectaWeb tree root protection system provides:

  1. Provides even distribution of traffic weight
  2. Guards against root damage from digging out
  3. Ensures unrestricted passageways for oxygen and water to roots
  4. Protects roots from contamination by non-woven geotextile (MultiTrack SNW 40 UV)
  5. Reduced compaction of sub-soils
  6. Keeps tree healthy

ProtectaWeb tree root protection system specification

ProtectaWeb is a three-dimensional cellular confinement system manufactured from strips of HDPE. The strips are ultrasonically welded together to create a flexible, load-bearing, free-draining mattress of interconnecting cells. The structure and properties of the system spread the vertical load over larger footprints, thereby reducing the impact on the sub-soil beneath.

Our MultiTrack SNW 40 UV Geotextile is highly puncture resistant and, combined with its high tensile strength, provides resilience and stability to the system. The 300g/m2 MultiTrack Geotextile is proven to filter four times more heavy metals and hydrocarbons than standard geotextiles as water moves through the system.

BS 5837:2012 and APN 12 both recommend the use of 3D cellular confinement systems as part of any sub-base for building vehicular access paths above the root protection area of existing trees which are subject to a Tree Preservation Order.

Design flexibility

ProtectaWeb panels can be stacked to meet each site’s individual requirements for ground level.

Similarly, if finished ground levels need to be kept to a minimum but initial construction loadings call for a higher level, ProtectaWeb can be placed in layers then removed to leave a single piece for final surfacing.

If more substantial kerbs are to be used instead of conventional timber edging boards, concrete haunching can be applied to the perimeter of ProtectaWeb.

We offer free site consultation, standard and site-specific CAD drawings and exceptional customer service at every stage.

ProtectaWeb specification Installation guide

Related case studies

Related case study

Thetford Woodland Lodges

Thetford Forest is the UK’s largest man-made lowland forest. It’s patchwork of pines, heathland and broadleaves provides the ideal setting for a great day out, and a welcome refuge for a rich variety of animal and plant life. Due to the weight involved, it was clear that the correct selection of ProtectaWeb depth was imperative to the success of the project.

Wooden Lodge Foundations
Wooden Lodge Foundations
Read more
Related case study

Chelsea Garden Project

The Hospital of St John and St Elizabeth in London is one of the UK’s largest independent charitable hospitals. This project involved a need to solve the design constraints for the relocation of a Chelsea Flower Show garden to a hospice, on part of the hospital site. We provided geosynthetics products, and our experts led on-site product installation supervision to devise innovative solutions.

Hospital of St John & St Elizabeth
Hospital of St John & St Elizabeth
Read more
Contact us

Contact us

Whether you are looking for live project support or are in the initial stages of specification, we are always on hand and happy to help. Alternatively call us on 01543 440 480.

Share this page