Guide
Buying a house with Japanese knotweed: surveys, plans and costs
Updated
If a valuer finds Japanese knotweed, the purchase usually goes on once a specialist survey and a management plan are in place. RICS's professional standard gives valuers a decision tree based on risk to decide what is needed, and the published prices here put a survey at a median of £299 and a treatment plan at a median of £1,900.
What the valuer looks at
RICS reissued its Japanese knotweed and residential property standard as a Professional Standard in October 2022. It contains a decision tree based on risk level to help valuers decide the management approach, and RICS says the categorisation gives the clarity that is essential for lenders.
What a buyer usually pays for
| Step | Median published price | Firms publishing |
|---|---|---|
| Survey and management plan | £299 | 5 |
| Herbicide treatment plan | £1,900 | 7 |
From this site's index of specialists' own prices (every row, with its source); the survey and treatment guides list every firm.
Questions to settle before exchange
- Who pays for the survey and plan: buyer or seller?
- Does the plan carry an insurance-backed guarantee your lender will accept, and is it transferable to you?
- Has the stand been treated before, and is there paperwork showing it?
This page explains published prices and the RICS standard; it is not legal, valuation or mortgage advice.