Selling a house with Japanese knotweed might seem like facing an impossible challenge, but with the right approach, your property doesn’t have to sit on the market forever or sell for pennies on the pound. While this invasive plant certainly complicates matters, there are still viable paths to a successful property sale.
Recent studies reveal alarming statistics about this persistent plant’s impact on UK homes. It’s estimated that 4-5% of UK houses are currently affected by Japanese knotweed, either directly or indirectly. Properties infested with this invasive species typically experience value reductions of up to 10% or more, with some severely affected homes seeing drops of 20%. What’s more, sales involving Japanese knotweed are significantly more likely to fall through, creating heartbreak for sellers who thought they’d found a buyer.
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What is Japanese Knotweed & Why Does It Cause So Much Trouble?
Japanese knotweed (Fallopia japonica) is a non-native invasive plant species known for its bamboo-like stems, heart-shaped leaves, and impressive growth rate of up to 10cm per day during summer. Originally introduced to the UK as an ornamental plant in the Victorian era, it has become one of the country’s most problematic invasive species.
The plant causes such concern because its extensive root system (rhizomes) can spread up to 7 metres horizontally and 3 metres deep, potentially damaging foundations, drainage systems, and garden walls. Its aggressive growth habit makes it capable of exploiting tiny cracks in concrete and brickwork, leading to structural issues over time.
Can You Sell a House with Japanese Knotweed?
Yes, you can sell a house with Japanese knotweed, but it comes with significant challenges. The presence of this invasive plant typically leads to:
Longer time on the market
Reduced property value (typically 5-10%, sometimes more)
Limited pool of potential buyers
More complicated mortgage negotiations
Higher risk of sales falling through
Many mortgage lenders are hesitant to approve loans for properties affected by Japanese knotweed, restricting your potential buyers to cash purchasers or those able to secure specialist lending. This limitation naturally affects both your property’s saleability and its market value.
How to Deal with Japanese Knotweed When Selling Your Home?
When faced with selling a property affected by this invasive plant, you generally have three main options:
Treat the knotweed first, then sell
Sell via auction
Sell to a We Buy Any House company like Property Saviour
Each approach has its advantages and disadvantages, depending on your timeline, financial situation, and how extensively the knotweed has affected your property.
Option 1: Treat Then Sell
If you have the time and resources, treating the Japanese knotweed before selling can help you achieve a higher sale price. This typically involves:
Hiring a PCA-accredited specialist company
Implementing a treatment plan (usually herbicide-based)
Obtaining an insurance-backed guarantee
Marketing your property with evidence of treatment
This approach may take 2-5 years for full treatment but will reassure buyers and lenders. Even after treatment, you’ll still need to declare the property’s history with knotweed, but having a professional management plan in place makes a significant difference.
Option 2: Auction Sale
Selling a property with Japanese knotweed at auction can be an effective compromise between price and speed. Auction benefits include:
Experienced buyers familiar with problem properties
Higher proportion of cash buyers (avoiding mortgage restrictions)
Binding sales with very low fall-through rates (under 1%)
Competitive bidding potentially driving up price
However, you should expect to set your reserve price 35% below standard market value, depending on the severity of the infestation.
Option 3: Sell to a Cash Buying Company
If you need a guaranteed, hassle-free sale, companies like Property Saviour specialise in buying problem properties, including those affected by Japanese knotweed. While this option typically offers the lowest price (often 70-80% of market value), it provides certainty and speed that other methods cannot match.
At Property Saviour, we understand the stress of trying to sell a knotweed-affected property. We’ll buy your home directly, with no chain, no viewings, and completion in as little as 14 days. Our straightforward approach means no last-minute price reductions or sales falling through.
Sell with certainty & speed
How Much Does Japanese Knotweed Devalue Property?
The impact of Japanese knotweed on property value varies depending on several factors, including infestation severity, proximity to buildings, and whether treatment has begun. The table below provides a general guide to potential devaluation:
| Scenario | Typical Devaluation | Notes |
|---|---|---|
| Knotweed present but no treatment | 20-30% | Highest risk for mortgage lenders |
| Knotweed with treatment in progress | 10-15% | More acceptable to some lenders |
| Historic knotweed (fully treated) | 5-10% | Insurance-backed guarantee helps |
| Knotweed in neighbouring garden | 20-30% | Depends on proximity to boundary |
These figures represent typical devaluation rates we’ve observed in the market, but each property is unique. The stage of growth, extent of infestation, and proximity to structures all influence how much your specific property might be affected. Lenders and buyers have become somewhat more reasonable about Japanese knotweed in recent years, but it remains a significant concern in property transactions.
Do Sellers Have to Disclose Japanese Knotweed?
Absolutely. You are legally required to disclose the presence of Japanese knotweed when selling your property. During the conveyancing process, you must complete the TA6 Property Information Form, which specifically asks about Japanese knotweed (question 7.8).
If you answer untruthfully or select “Not known” when you’re aware of its presence, you could face legal action from the buyer for misrepresentation. If a seller lied about Japanese knotweed, the new owner could claim significant damages, including:
The cost of professional removal
Loss in property value
Legal costs
Additional damages for distress
Several court cases have resulted in substantial compensation being awarded to buyers who weren’t informed about knotweed. In one notable 2023 case, a homeowner faced a legal bill exceeding £200,000 after falsely claiming they were unaware of knotweed on their property.
Do Mortgage Surveyors Look for Japanese Knotweed?
Yes, identifying Japanese knotweed is now part of standard surveyor training. Mortgage surveyors are specifically instructed to look for this invasive plant during property inspections, and they’re required to report its presence to the mortgage lender.
Surveyors check both the property itself and nearby land (typically within 7 metres of the boundary), as what is the 7 metre rule for Japanese knotweed relates to the distance at which knotweed on neighbouring land might affect the subject property.
If you’re wondering “is Japanese knotweed a deal breaker” for mortgages, the answer is increasingly nuanced. While some lenders still refuse properties with any knotweed present, many now take a more measured approach, considering factors like:
Distance from buildings
Evidence of damage
Presence of a management plan
Insurance-backed guarantees
Should I Be Worried If My Neighbour Has Japanese Knotweed?
YES, YOU SHOULD BE CONCERNED IF YOUR NEIGHBOUR HAS JAPANESE KNOTWEED. The invasive plant can spread rapidly across property boundaries, potentially affecting your home’s value and making it harder to sell in future.
With its aggressive root system capable of extending up to 7 metres horizontally, knotweed from a neighbouring garden could eventually reach your property’s foundations or drainage systems. Even more worrying, if you decide to sell, you’ll need to declare your neighbour’s knotweed on the TA6 form if it’s within 3 metres of your boundary – potentially putting off buyers and lenders.
If you spot knotweed in a neighbour’s garden, we recommend having a friendly conversation about it first, as they may be unaware of what it is or the potential implications. If they’re uncooperative, you may need to involve your local council or seek legal advice.
How to Get Rid of Japanese Knotweed: Professional vs DIY Approaches
When tackling Japanese knotweed, professional treatment is nearly always recommended. DIY attempts rarely succeed and may actually make the problem worse by stimulating growth or causing spread. Professional knotweed removal typically follows one of these approaches:
Herbicide treatment (2-5 years)
Excavation and removal (quicker but more disruptive)
Combined methods for severe cases
How much does it cost to get rid of Japanese knotweed? Professional treatment costs typically range from £2,000 to £5,000 for an average-sized garden, depending on the extent of the infestation and the chosen method. Complete excavation for severe cases can exceed £10,000.
Will the council remove Japanese knotweed from private property?
Normally not. While local councils are responsible for managing knotweed on public land, they don’t typically offer removal services for private properties. However, they may take action if a neighbour’s knotweed is affecting public areas or if they’re allowing it to spread to other properties.
Is It Worth Getting Japanese Knotweed Indemnity Insurance?
Japanese knotweed indemnity insurance can provide valuable protection for both buyers and sellers in certain situations. This specialised insurance typically covers:
Legal costs if a neighbour makes a claim against you
Costs of treatment if previously undetected knotweed appears
Diminution in value claims
For sellers, offering to pay for this insurance can make your property more attractive to cautious buyers. For buyers, it provides peace of mind when purchasing a property with a history of knotweed or in an area where knotweed is common.
Policies typically cost between £300 and £1,000, depending on coverage limits and the property’s specific circumstances. While not necessary in all cases, it can be particularly valuable for properties with treated historic knotweed or where there’s knotweed in a neighbour’s garden.
Do Estate Agents Have to Tell You About Japanese Knotweed?
Yes, estate agents are legally obligated to disclose the presence of Japanese knotweed if they’re aware of it. Under the Consumer Protection from Unfair Trading Regulations (2008), estate agents must not omit material information that would affect a buyer’s transactional decision.
If an estate agent knowingly conceals information about Japanese knotweed, they could face:
Financial penalties
Damage to their professional reputation
Potential civil action from the buyer
However, if the agent genuinely doesn’t know about the knotweed, they can’t be held responsible for not disclosing it. This is why sellers should always be upfront about any knotweed issues, as the legal responsibility ultimately falls on them.
My Garden is Overrun with Invasive Species: What Can I Do?
If your garden is overrun with Japanese knotweed or other invasive species, taking prompt action is essential. Beyond impacting your property’s value, allowing invasive plants to spread can potentially lead to legal issues with neighbours or even environmental authorities.
For Japanese knotweed specifically:
Confirm identification through a professional survey
Don’t attempt DIY removal which often makes things worse
Get quotes from PCA-accredited specialists
Consider whether treatment or excavation is more appropriate
Ensure any work comes with an insurance-backed guarantee
For other invasive species like bamboo (sometimes called “Japanese knotweed 2.0” due to its similar invasive nature), giant hogweed, or Himalayan balsam, similar principles apply, though treatment methods may differ.
Who is Responsible for Removing Japanese Knotweed?
Responsibility for Japanese knotweed removal lies with the property owner where the plant is growing. If knotweed is present on your land, you’re responsible for ensuring it doesn’t spread to neighbouring properties. While you’re not legally obligated to remove it from your own land, you could face legal action if you allow it to spread to adjacent properties.
When Japanese knotweed is in a neighbour’s garden, they are responsible for its management. If their knotweed spreads to your property, you may have grounds for a private nuisance claim, potentially recovering removal costs and compensation for diminished property value.
For knotweed on public land, the relevant authority (council, highways agency, etc.) is responsible. If public knotweed is affecting your property, report it to the appropriate authority and document all communications.
How Does Japanese Knotweed Affect the Sale of Property?
Japanese knotweed affects property sales through several key channels:
Mortgage availability: Many lenders have specific policies restricting loans on affected properties
Buyer pool: Reduced number of potential buyers, as many are deterred by knotweed concerns
Sale timeline: Extended sales process due to additional surveys and lender requirements
Negotiating position: Buyers often use knotweed as leverage to drive down price
Legal requirements: Mandatory disclosure on the TA6 form during conveyancing
The extent of these effects varies based on infestation severity and whether treatment plans are in place. Properties with untreated knotweed face the greatest challenges, while those with professional management plans and insurance-backed guarantees fare better.
Your Options for Selling a House with Japanese Knotweed
Selling a property affected by Japanese knotweed presents challenges, but it’s far from impossible. Understanding your options helps you make the right decision for your circumstances:
For maximum value: Treat first, then sell on the open market
For a balance of speed and price: Consider auction sale. But expect 30% or more discount against valuation.
For guaranteed completion and minimal stress: Sell to a specialist buyer like Property Saviour
At Property Saviour, we’ve helped countless homeowners escape the stress of selling knotweed-affected properties. We understand the challenges you’re facing and offer a straightforward solution: we’ll buy your property directly, regardless of its knotweed status, with no hidden fees or last-minute price reductions.
Don’t let Japanese knotweed hold you hostage in a property you need to sell. Contact Property Saviour today for a no-obligation cash offer and discover how we can help you move forward with certainty and peace of mind.
Sell with certainty & speed
Property Saviour Price Promise
- The price we’ll offer is the price that you will receive with no hidden deductions.
- Be careful with ‘cash buyers’ who require a valuation needed for a mortgage or bridging loan.
- These valuations or surveys result in delays and price reductions later on.
- We are cash buyers. There are no surveys.
- We always provide proof of funds with every formal offer issued.
We'll Pay £1,500 Towards Your Legal Fees
- No long exclusivity agreement to sign because we are the buyers.
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- We share our solicitor’s details and issue a Memorandum of Sale.
Sell With Certainty & Speed
- Our approach is transparent and ethical, which is why sellers trust us.
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