Japanese knotweed disclosure under TA6: what to ask

The Law Society's TA6 Property Information Form asks the seller whether the property is affected by Japanese knotweed (Yes, No or Not known). A Yes leads to further questions: when they became aware, what treatment has been done, by whom, and whether there is a management plan.

What to ask and look for:

1. A treatment guarantee. Reputable firms (Property Care Association members) give an insurance-backed guarantee, often 5 to 10 years, covering regrowth. Without one, the evidence of treatment is weak.
2. The management plan: a written schedule of treatment and monitoring, usually running for some years after the last treatment.
3. The boundary. Knotweed spreads underground across boundaries, so look on both sides of the line.
4. The lender's view. Most lenders accept treated knotweed with a proper guarantee; some won't lend where it is untreated.
5. A look. Stems are reddish and hollow like bamboo, with heart-shaped leaves in a zig-zag; easiest to spot from May to September.

The seller's answer on the TA6 and a surveyor's inspection remain the checks that matter at the property. Certaby's property checks add whether knotweed has been recorded near the postcode.

Source: Law Society: TA6 Property Information Form

Last updated 27 October 2026.