A Japanese knotweed survey is a straightforward site inspection followed by a written report, and knowing what to expect takes the worry out of it. A surveyor confirms the species, maps the stand, assigns the RICS management category and sets out a costed plan. Our page on the survey and report covers the service in full, and this guide walks through what happens on the day and what the report you receive will contain.
What happens at a Japanese knotweed survey?
At a knotweed survey a specialist visits the property, confirms whether the plant is Japanese knotweed, and inspects the stand and the ground around it to establish its extent, its proximity to the house, boundaries, drains and structures, and the likely spread of the rhizome. The inspection is visual and non-destructive in most cases, walking the site and recording the canes, their condition and their relationship to nearby features. It usually takes under an hour for a domestic garden, and it is the basis for everything in the report that follows.
What is in the survey report?
The survey report confirms the species, maps the stand, states the RICS management category, assesses the risk to the property, and sets out a costed treatment or removal plan, so it is both a diagnosis and a plan of action. It is written so a lender, solicitor or buyer can rely on it, which is what makes it useful in a sale. Where the report supports a management plan and an insurance-backed guarantee, it becomes the document that satisfies a mortgage valuer and unblocks a transaction.
What is the RICS management category?
The RICS management category places the stand on a scale from A to D under the 2022 professional standard, describing how it should be managed based on its extent and proximity rather than a raw danger rating. The category tells a lender and a buyer how the situation should be handled and feeds into the plan. Assigning it is a core purpose of the survey, because it translates what the surveyor sees on the ground into the standard language that lenders, surveyors and conveyancers use to assess a stand.
What happens after the survey?
After the survey you receive the report and a costed plan, and you can decide how to proceed: arrange a herbicide programme or excavation, use the report and plan to satisfy a lender, or negotiate a price where you are buying or selling. Where treatment goes ahead, the survey underpins the management plan and the guarantee. So the survey is the starting point rather than the end: it turns an uncertain stand into a documented, costed situation you can act on, whatever your reason for commissioning it.
Common questions
- How long does a knotweed survey take?
- A domestic survey usually takes under an hour on site, with the written report following shortly after, often within a week or two. The report is what a lender or solicitor relies on, so it is worth allowing time for it.
- How much does a knotweed survey cost?
- A specialist knotweed survey typically costs from around a few hundred pounds depending on the site and the report required, indicative and confirmed on enquiry. It is a modest cost against the value it adds in a sale.
- Is a mortgage valuation the same as a knotweed survey?
- No. A mortgage valuer will flag knotweed but does not map it or produce a management plan. A specialist survey provides the detailed report, category and costed plan a lender then wants.