Japanese Knotweed Insurance Guide

Making sure you have the right protection against the costs associated with the discovery of Japanese knotweed could be one of the most prudent financial decisions you make when buying property. Our in-depth guide answers your questions about Japanese Knotweed Insurance.

Quick Facts

  • The average cost of a Guaranteed Japanese knotweed Management Plan in the UK is £5,000
  • In recent years Japanese knotweed Indemnity Insurance has helped protect many homeowners against the risk of Japanese knotweed.
  • An Insurance Backed Guarantee on any Japanese knotweed work is a must for most lenders.
  • Environet offer an “AA-“ Rated Insurance Backed Guarantee – the best in the market.

Japanese knotweed is a beast of a plant to get rid of once it takes root in a property. Homeowners can spend months or even years, as well as large amounts of effort and money, trying to kill it off as it nevertheless continues its relentless advance — above and underground. The risks to the property and the homeowners themselves are all too real. It is for this reason that many people look to the insurance market for help. Not only to insure against the risks of finding and having to deal with Japanese knotweed on a property, but also in guaranteeing it won't come back once it is dealt with.


Trust us to give you the right information:

Can you get indemnity insurance for Japanese knotweed?

A “No” or “Not Known” answer to the question relating to Japanese knotweed on the Law Society's TA6 form can leave a buyer vulnerable to future costs associated with Japanese knotweed. Thankfully the risk can now easily be alleviated with a low-cost knotweed insurance indemnity policy, providing cover for the new homeowner and their lender, addressing the uncertainty. Japanese Knotweed Indemnity Insurance is available for those properties not known to be affected, to provide protection against the future infestation of Japanese knotweed anywhere on the property. Policies generally cover:

  • Cost of survey/report by a specialist company
  • Cost of all treatment of regrowth over the insured period
  • Cost of repairs to damage caused by knotweed on the insured property up to a limit of indemnity typically equal to the value of the property
  • Cost of legal defence from claims made by third parties

For a one-off premium the policy covers you and your successors in title for 5 or 10 years, and the lender for the duration of the mortgage

If you are buying a property and are concerned about the risk of knotweed, it may be worth considering indemnity insurance. Any advice or insurance enquiries should be directed through your conveyancing solicitor.


Can you insure against Japanese knotweed?

Many people wonder if they can insure against Japanese knotweed so that their property is protected against regrowth. The short answer is: Yes, via insurance firms and specialist Japanese Knotweed companies. But there's a bit more to it than that. A Japanese knotweed removal company may say they guarantee their work for a certain period, but what guarantee would you have that they'd live up to their word? After all, it's easy for any company to offer a guarantee, but if it's not backed up by something solid like insurance, what good is it?

  • Always check the fine print of any guarantees being proposed by a knotweed specialist. Some mislead by saying their guarantees are insurance backed. A check on the small print will reveal that the insurance to which they refer is simply their Professional Indemnity or Public Liability insurance, neither of which would entertain a claim if the company ceased trading.
  • Make sure the insurer behind any insurance backed guarantee (IBGs) is rated. We offer insurance backed guarantees for up to 10 years underwritten by an “AA-” rated insurer, with limits of liability up to £100,000
  • • Ask to see a sample guarantee and read the small print – you might be surprised to hear that for some you have to pay to make a claim, and that there is no certainty as to when the insurance element of the guarantee kicks in.

Does house insurance cover Japanese Knotweed?

Most household/buildings insurance policies will not cover liabilities associated with Japanese knotweed, with the possible exception of legal expenses cover, where legal claims are made or brought by the insured. On some comprehensive buildings policies, subsidence as a result of Japanese knotweed may also be covered – although successful claims are only likely to be made when you can prove that you have taken reasonable steps to eradicate the Japanese Knotweed before the subsidence took place.

  • Damage caused by Japanese Knotweed is unlikely to be coved by house insurance as it is more than likely that it would have occurred gradually over time. Therefore, an insurer would be able to argue that the damage was caused by your failure to act.
  • If you are buying a property and you are concerned about possible risks from Japanese knotweed, you may be able to secure a Japanese knotweed indemnity policy. This would cover the costs of cost of a Japanese knotweed survey, the treatment or removal of the infestation, as well as any costs in relation to damages to the property and legal expenses because of claims made against you.

Is japanese knotweed removal covered by home insurance

Most home insurance policies don't cover the cost of any treatment or removal of the fast-growing plant, so you'll need to sort this out yourself.

  • Japanese knotweed is best removed by professionals as soon as it is discovered. The costs associated can run into the thousands, so many people are now choosing to protect themselves from the liability by opting for Japanese knotweed indemnity Insurance.

Does Japanese knotweed affect house insurance?

Because Japanese knotweed is not generally covered by your buildings insurance, they are generally unconcerned about the presence of Japanese knotweed on a property. This means that it should not affect your ability to secure home insurance, nor result in a higher premium

  • You are not obliged to tell your home insurance provider if you discover Japanese knotweed on your property, unless of course they specifically ask you – in which case you must declare it.
  • This does not mean you should ignore the problem once identified. It is important to take professional advice and get a treatment programme in place as soon as possible to prevent any future issues
  • If you fail to act on an infestation, an insurance provider may reject a future claim based on your negligence.

Can you get Japanese knotweed insurance backed guarantees?

We're not surprised if you're confused about the various insurance backed guarantees (IBGs) available from different knotweed companies, so we thought the heads-up might help you. The majority of established knotweed companies give some form of guarantee, most promising to retreat any regrowth free of charge during the guarantee period.

Insurance backed guarantees go a step further, by ensuring the guarantee obligation is met even if the treatment company becomes insolvent. All the main banks and lenders will require a treatment programme and IBG on knotweed affected property before they are willing to lend. The IBG has therefore become an essential requirement for any owner of knotweed affected property

  • Not all IBGs are the same, providing differing levels of cover and security. Make sure you get what suits you and your property best.
  • Some Guarantees are not actually “Insurance Backed” – the contractor is actually referring to their PI or EL Insurance, which would not cover you if they ceased trading.
  • Most IBGs provided by other Japanese knotweed specialists are backed by non-rated insurers. The insurer that underwrites Environet guarantees is “AA-” rated. The financial standing of the insurer is just as important as that of the contractor – as the 2008 financial crisis made all too apparent.
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What Makes our Insurance Backed Guarantee Market Leading?

AA- Rated Insurer Accepted by all Major Lenders

Our guarantees are underwritten by CLS Property Insight Ltd on behalf of Great Lakes Insurance SE, UK Branch, part of the Munich Re group of companies. Enjoying an S&P AA- rating, you won't find better security than that. It goes without saying that these are accepted by all the major banks and building societies in the UK.

£100,000 Limit of Liability

Cover can be arranged with a limit of liability matching the contract value (starting at £5,000) up to £100,000. Larger values can be obtained subject to insurer approval. Check that the amount of cover offered is adequate.

Cover for Property Damage Resulting from Regrowth option

We offer the option to cover repairs for damage caused to the property and hard-landscaping by knotweed regrowth. The standard cover has a limit of liability at £10,000; greater cover can be provided where required. The majority of IBGs specifically exclude cover for property damage, as do most building's insurance policies.

Cover Effective in Days – No Delays

Most companies will issue their IBG when the work is complete, often 2 to 3 years or more after instruction. Our IBG can be issued following our first visit/treatment, subject to receipt of full payment. This means you have certainty that you are fully covered from day 1.

Up to 10 Years' Cover

We can provide guarantees for 5 or 10 years to cover the affected area plus buffer zone, or to cover the entire property. Ask us about our Platinum cover

No Excess Charges

Unlike many of our competitors, our guarantees have no excess charge, or fee payable for making a claim.


Our IBGs are assignable to new freehold or leasehold owners. If you're buying a property affected by knotweed, make sure the guarantee is transferred into your name before completion

Minimal Restrictions

Many IBGs contains restrictions, so for example you might find your guarantee becomes invalidated if the ground is disturbed, creating a severe restriction on the amenity value of the property. At Environet, we work closely with you to select the method that allows you to use the land during the guarantee period with no onerous restrictions.

To Start Fixing Your Knotweed Problem Today,

Call our Team for Specialist Advice and Effective Solutions.

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We had a reservation on one of our developments where the customer was extremely nervous about historic Japanese knotweed. With help from Environet, including their treatment and a 5 year insurance backed guarantee, we were able to secure knotweed indemnity insurance from Countrywide Legal Indemnities. It was this policy, which covers the knotweed liabilities such as cost of any further treatment, repairs to damage caused by knotweed, and legal expenses cover, that finally satisfied the buyer, his solicitor and lender that they should proceed with the purchase. Thank you to Environet and CLI for making it happen.

Donna Cole, Field Sales Manager - Persimmon Homes PLC


Environet provided me with a "matter of fact" survey/report (to prove to my buyer that there is no knotweed on my property and to assess the risk of it spreading from neighbouring land..) and provided expert guidance on options and solutions going forward (Countrywide Indemnity insurance or their insurance backed guarantee). I had a nice "knotweed chat" with the very knowledgeable surveyor and she did not in any way try to frighten me into choosing the more expensive option, but reassured me that they had different solutions depending on what the buyer required.

Bjorn Lie, Trustpilot


I have now sold my flat and I'm sure the sale went through because of the reputation Environet has and the weight of its 10 Year Insurance backed guarantee. This made the buyers and their lender more comfortable.

Tara O'Neill, Trustpilot