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Project Overview
Our client in North London contacted our team, having recently purchased the property and identifying Japanese knotweed in their garden. At the survey, our consultant found the knotweed was present in both the client’s property and the adjacent neighbouring property, with growth around a wooden sleeper retaining wall within the rear garden.
Works Undertaken: December 2025
Area affected: 8m2 across both properties
Challenge
The site was affected by a mature and well-established stand of knotweed located along the rear boundary. The main crown was positioned tight against the boundary fence, with rhizome extension and above-ground growth encroaching into the client’s lawn area. This encroachment was causing structural damage to the timber sleepers used to retain the raised lawn, with knotweed canes emerging through and behind the sleeper structure.
In addition to the primary crown, secondary growth had extended away from the main stand, indicating active lateral rhizome spread. The presence of emerging canes beyond the mature growth area demonstrated an ongoing risk of further structural damage and progressive encroachment towards the property, particularly if left unmanaged.
Site constraints significantly complicated the management approach due to restricted access to the client’s garden, limiting the use of machinery and working space. A live power cable along the boundary was safely exposed and protected during excavation.
Furthermore, there was no permission granted to excavate within the neighbouring land, despite the proximity of the main crown to the boundary. This restriction necessitated a carefully considered treatment strategy that addressed the on-site impacts of the infestation, while managing the risks associated with off-site rhizome presence and limited site access.
Solution
Due to the maturity and extent of the Japanese knotweed, our client opted for a Resi-Dig-Out solution to achieve complete removal, rather than a longer-term herbicide treatment programme.
Dead canes were cut and removed before systematic excavation of the affected lawn area. Extensive, healthy rhizome was found throughout the site, including at depths of over 1.5 metres, particularly along the boundary fence and beneath the timber sleepers. All contaminated soils were carefully sifted on site, with knotweed material removed and bagged for disposal.
Due to the restriction on excavating the knotweed on the neighbouring property, a root barrier trench was installed along the fence line for containment.
Outcome
All Japanese knotweed and contaminated soil were successfully removed from within the property boundary and the root barrier installed provides our client with long-term protection from future encroachment.
The affected area was left as bare soil, allowing the garden to be immediately reinstated and landscaped, unlike herbicide treatment programmes where ground disturbance is restricted.
A five-year insurance-backed guarantee was issued on the property, providing long-term assurance and lender confidence for any future sales of the property.
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