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Using root barriers on sites infested with Japanese Knotweed, Dublin, Ireland

(DENDRO-SCOTT™ Root Barrier)





It is an offense under Section 52 of the Wildlife Act, 1976 as amended by the Wildlife (Amendment) Act, 2000 (subsection (7) to release or allow any exotic (i.e. non-native) species, or to attempt to establish it in the wild, other than in accordance with a license given under the Act to do so. See:



There are several instances where installation of a suitable root-barrier may be required as part of a Japanese Knotweed management plan, for example;


  • Where Japanese Knotweed infestations near existing structures, it may not be possible to excavate and remove the Japanese Knotweed in its entirety due to undermining foundations.

  • Where Japanese Knotweed infestations cross land ownership boundaries, it is not usually possible to excavate beyond the party wall / fence line therefore a suitable root barrier should be used to protect re-infestation from the contaminated site.

  • Where proposed development will allow, a reduced-level partial excavation may be feasible to reduce disposal costs however a suitable root-barrier must be installed to prevent future damage to the proposed development.



The presence of the invasive Knotweed plant species on a development site can have huge financial implications. Knotweed Control Ireland offers a solution to this problem at a fraction of the cost. The DENDRO-SCOTT™ Root Barrier, in tests and general use, has a provenance of over a quarter of a century, in which time there has not been one reported incidence of Knotweed or tree roots penetrating the material. The manufacturers have stated, subject to the ground not being contaminated with specific chemicals the effective life expectancy of the material in the ground is well in excess of 50 years (the highest classification possible). (dependent on the soil profile), the technique used is to install the DENDRO-SCOTT™ Root Barrier vertically to a depth of at least 1-3m around the whole contaminated area or construction footprint. A horizontal section (which can be supplied as a single sheet) is then laid over the contaminated area, glue and sealed to the already installed vertical sections, thus completely sealing in the Knotweed, if required. The structure is then built over this sealed area or just covered with a sand and topsoil layer.


Knotweed Control follows guidelines set out by the Environment Agency in the Knotweed Code of Practice:

Managing Japanese Knotweed on Development Sites (2013).


Root Barriers to Prevent the Spread of Knotweed across Property Boundaries.

Root barriers, as well as being used to aid cell burial of Japanese Knotweed on construction sites, can also be used to prevent the spread of Japanese Knotweed to and from neighboring land. The root barrier is normally installed vertically along the boundary to a depth of between 1-3 meters


Knotweed Control Ireland provides a Root Barriers Services that includes:

  • Flexible Permeable Root Barrier

  • Rigid Root Deflectors

  • Prefabricated Root Cells

  • A range of widths and lengths(max 40m x 150m)

  • Complies with Environment Agency CoP-2013 on Japanese Knotweed

  • Root barriers comply with BS5837

  • Root barriers sourced from Irish suppliers





In all scenarios it is essential that root-barriers are installed correctly, as a root barrier is only effective if it has been installed in the correct way with the correct overlay / joints. Supervision by a suitably qualified person is essential during root-barrier installation.

For further information please contact: or call us on 085 1699 592


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