Japanese Knotweed Management Plan: What It Includes and Why Lenders Ask for One

Published by PCA Certified Survey Team • Updated November 2026

If a surveyor or mortgage valuer flags Japanese knotweed, the next request is almost always for a knotweed management plan, often shortened to KMP. Without one, many lenders will pause or decline the mortgage. This guide explains what a KMP is, what it should contain and how to get one quickly.

1. What Is a Knotweed Management Plan?

A KMP is a written document prepared by a qualified specialist after a site survey. It records where knotweed is, how far it is from the property, which treatment method will be used, how long treatment will last, and how the work will be monitored and guaranteed. The Property Care Association (PCA) publishes a code of practice that most reputable plans follow.

2. What Lenders Usually Expect It to Include

• Site plan and photos showing the extent of the infestation and distances to buildings and boundaries.
• Risk category under the 2022 RICS guidance.
• Treatment method: herbicide programme, excavation, root barrier or a combination.
• Timescale: typically a multi-season programme for herbicide work.
• Monitoring visits after treatment.
• An insurance-backed guarantee (IBG) that transfers to future owners, often for 5 to 10 years.

Requirements vary by lender, so the buyer's broker should confirm what their lender needs before the plan is commissioned.

3. KMP vs. Survey Report

A survey report identifies and measures the knotweed. A management plan goes further: it is a commitment to treat it, with a contractor responsible for the work. Some firms combine both in one document. See our guide to survey costs.

4. How Long Does a KMP Last?

Herbicide-based plans commonly run over three to five growing seasons, followed by monitoring. Excavation-based plans can be completed faster, which suits tight sale timelines. The guarantee period starts once treatment is completed or under way, depending on the provider.

5. Who Should Pay for It?

Usually the seller arranges and pays for a KMP, because it removes an obstacle to the sale and is declared on the TA6 form. In practice buyers and sellers sometimes negotiate the cost into the price. Get legal advice from your conveyancer on your own situation.

6. Red Flags in a Management Plan

• No site survey, only a desk-based estimate.
• No named contractor or PCA membership.
• A guarantee that is not insurance-backed, so it would fail if the company closes.
• No details of waste disposal for any excavated soil.