Ben Lindley, Company Director at Japanese Knotweed Ltd. Last reviewed on 5th June 2026.
The “New-Build” TA6 Gap
In this article we look at the responsibilities that UK housebuilders have when it comes to dealing with knotweed on their development sites, and how declaring the presence of knotweed is managed differently to homeowners. We look at why this is so important for new-build construction in the UK, and what steps can be taken to eliminate risk of legal implications after hand-over.
Homeowners preparing to sell their property must complete the Law Society’s TA6 Property Information Form that includes a tick box to declare knotweed, but there is concern around whther there is an equivalent question asked to developers when they hand over to a management company.
Is there a TA6 form for UK developers? The answer is “No”.
There is no mandated standard form (equivalent to the TA6 Property Information Form) used explicitly for the handover between a developer and a managing agent or property management company.
Instead, this transaction relies on a comprehensive handover checklist and legal disclosures governed by trade bodies and standard development management agreements. Because a management company takes on the legal liability of managing communal land – where untreated Japanese knotweed could lead to costly lawsuits or even criminal prosecution – the equivalent information is captured through different frameworks:
- The MAP Handover Information Checklist
The Managing Agents Partnership (MAP), alongside ARMA (Association of Residential Managing Agents) and IRPM (The Property Institute), provides industry-standard handover checklists. Under the Grounds Maintenance and Environmental section of these handovers, developers are explicitly required to disclose:
- Invasive Species Logs: Active declarations of Japanese Knotweed, Giant Hogweed, or Himalayan Balsam.
- Site History & Land Remediation Reports: Documentation proving the soil was cleared or treated prior to or during construction.
- Ecology Surveys: Planning-stage biodiversity and land surveys detailing historical site issues.
- Mandatory Common-Area Disclosures
When a developer hands over the common parts to a management company, their solicitors will issue a bespoke Pre-Handover Questionnaire.
- The Specific Inquiry: The solicitor will specifically ask: “Are there any known invasive or noxious plant species affecting the communal areas, or have any such species been treated on-site within the last 5 years?”
- The Paper Trail: If the developer answers yes, they must legally hand over the Knotweed Management Plan (KMP) and a transferable 10-year Insurance-Backed Guarantee (IBG).
Consequences of non-disclosure
When a developer sells individual plots to the first buyers, they are not legally required to fill out a TA6 form. But – to counter this, conveyancing solicitors representing the buyers and the management company must proactively request a bespoke written declaration from the developer regarding evidence of any historical knotweed on the site.
Why managing agents enforce this – it’s the homeowner’s who ultimately pay
If a developer hands over land with proven identified but previously undisclosed knotweed the management company becomes liable for the cost of eradication. This also gets passed on to the leaseholders via service charges. Furthermore, if the plant spreads to neighbouring properties, the management company can be sued for private nuisance.
The solution
All developers should get a pre-purchase or pre-planning survey carried out by a knotweed specialist. The survey comes with a report detailing any invasive plants identified (not just knotweed) and the options for remediation. This – formally known as a Knotweed Management Plan (or KMP) provides the landowner and the developer with the information required to proceed in confidence. If you’d like more information, advice or a survey booked speak to us today.
To avoid potential risk of legal action from either managing agent or resident homeowners a survey is a simple and quick failsafe option. We’ve helped top UK housebuilders to successfully navigate the issues of knotweed on large development sites. It’s not a deal-breaker – but it must not be ignored and it must be dealt with by professionals.
Here’s one example – Morris Homes who asked us to survey and then remove knotweed (and Himalayan balsam) from a site planned for development: