ROOT BARRIER C3 – JAPANESE KNOTWEED BARRIER

What is C3 Root Barrier

Root Barrier C3 is a tough, flexible and puncture resistant barrier which is highly resistant to root penetration and designed to protect structures and services from tree root damage, as well as controlling the spread of invasive plants such as Japanese Knotweed, Giant Hogweed, Mare's Tail and Bamboo. The fabric is also highly resistant to natural acids, alkalis, bacteria and fungi, and conforms to the criteria required by the Environment Agency code of practice.

In the past, sites infested with Japanese Knotweed could only be developed after 3 to 4 years of herbicide control, and even then there was often a risk of the plant re-occurring during excavations. Installing Root Barrier C3 can make a site immediately available for use with no risk to structures, roads or drains – a cost effective and quick alternative to excavating and transporting infested soil off-site.

Installation configurations

• Vertical barrier – a buried sheet wall installed along a boundary or around a structure to prevent lateral rhizome spread, protecting services and preventing ingress from neighbouring sites.
• Horizontal capping – laid over treated or buried ground to protect buildings, paving and tarmac surfaces above.
• Containment cell (on-site burial) – contaminated soil is fully encapsulated within a sealed membrane cell and buried, avoiding costly transport to a licensed tip.
• Burial depth – containment cells should be buried at least 2m below ground (deeper, around 3m, for knotweed, and deeper again where badgers or rabbits are present) to protect the membrane from small mammals.

Technical specification

Root Barrier C3 is a sophisticated composite membrane consisting of triple coating and twin reinforcing layers thermally bonded together to produce an extremely tough, durable and puncture resistant, impermeable, flexible barrier against root penetration. It is UV stabilised and can be supplied in rolls up to 4.00m x 100.00m long as a special order, with the membrane site-weldable to form larger sheets with improved joint integrity.

Also used for

Beyond Japanese Knotweed, the same membrane is used to line tree pits and control sideways root spread into surrounding areas where roots can damage property, pavements and services. A buried perimeter sheet wall can prevent roots undermining foundations and control subsidence from ground shrinkage caused by trees drawing moisture from the soil, and encasing new service trenches protects pipes from root fracture while providing a physical warning during future excavations.

Product FAQs

• How is C3 Root Barrier installed to control Japanese Knotweed?

  It is installed as a vertical barrier to stop rhizome spreading sideways to or from a neighbouring site, as a horizontal cap to protect buildings and hard surfaces above buried rhizome, or as a fully encapsulated containment cell for on-site burial. Sheets are overlapped or site-welded, and containment cells are buried to at least 2m (3m for knotweed).
• How deep should a containment cell be buried?

  At least 2m below ground, deeper (around 3m) for knotweed, and deeper again where badgers or rabbits are present, to protect the membrane from small mammals.
• How long does Root Barrier C3 last?

  It has a life expectancy of over 50 years, which the Environment Agency recommends given that knotweed rhizome can remain dormant for at least 20 years.
• Can Root Barrier C3 be used for anything other than knotweed?

  Yes. It also protects against giant hogweed, mare's tail and bamboo, and is used to line tree pits, form buried perimeter walls to protect foundations, and encase service trenches to protect pipes from root fracture.