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Are mortgage lenders 'overly cautious' about properties with Japanese knotweed?
Sellers and buyers whose properties show signs of Japanese knotweed are being hit by harsh policies, according to a new report from Parliament's Science and Technology committee. But are lenders likely to change their approach?
Currently, properties that have the invasive plant Japanese knotweed within seven metres of their property line may be treated as at-risk by lenders, making it difficult to secure a mortgage deal for them.
The committee said this 'seven-metre rule' is being used as a 'blunt instrument' in some mortgage lending decisions and does not reflect the latest scientific evidence.
Here we take a look at what the latest research says about the threat of Japanese knotweed, reveal current lending policies and if any provider is willing to rebalance the effect the plant has on property sales.
The latest Japanese knotweed research
Japanese knotweed or fallopia japonica is an invasive fast-growing plant that can send its roots deep into the ground and cause damage to building foundations, drainage systems and walls.
It's an aggressive weed, first introduced into the UK in the mid-19th century, that has a bad reputation. If the plant is found near or in a property, it can significantly affect your ability to sell or for a buyer to get a mortgage.
Treatment programmes are long and can cost thousands of pounds, plus the infestation can lie dormant for many years.
However, the UK Parliament's Science and Technology committee report notes that the latest research on the weed released last year suggests the physical damage to property is no greater than that of other plants and trees that are not subject to the same controls.
Currently, any sign of Japanese knotweed nearby can have a 'chilling' effect on a property's sale, the committee found. Yet, mortgage lenders in other countries do not treat the plant with the same degree of caution as we do in the UK.
Why the framework needs to be updated
Before 2012, it was very difficult to get a mortgage on a property that was anywhere near an outbreak of Japanese knotweed.
To tackle this issue, the Royal Institute of Chartered Surveyors (RICS) set out a framework to help lenders assess the risk.
A surveyor will apply these categories to the property, so that lenders can judge the severity of the knotweed problem. The higher the rating, the less likely a mortgage lender is to agree to a mortgage over the property.
| Risk category | What this means for your property |
| Category 1 | Knotweed is found more than seven metres away in a neighbouring property, or an empty space like a railway bank or wasteland. |
| Category 2 | Knotweed is within sevenmetres of your property but not within it. |
| Category 3 | It is within the boundaries of the property but is within sevenmetres from a living space. You will need a professional opinion. |
| Category 4 | The worst. It is within seven metres of the living space and/or causing damage to walls, paths or foundations. This needs immediate professional intervention. |
The framework relies on the seven-metre rule to measure the scope of the problem.
However, the parliamentary committee's report says the origin of the widely used seven-metre rule was a 'throw-away remark' in a 1998 research paper.
Indeed, RICS has admitted that the framework is 'no longer current', yet it still forms the basis of mortgage decisions.
- Find out more: getting a mortgage with Japanese knotweed
How do mortgage lenders decide to lend?
Mortgage lenders have different risk-assessment policies on Japanese knotweed. However, we found most use the RICS framework and the opinion of their valuer when making a decision.
We asked all mortgage lenders for their policy on lending on properties with signs of Japanese knotweed and whether they had any plans to update their policy should RICS issue new guidance.
You can use the table below to see their comments.
What's next for Japanese knotweed lending policy?
Right now the committee says the RICS framework lacks a clear and comprehensive evidence base, causing unnecessary problems for buyers and sellers.
The parliamentary committee is calling for a more nuanced and evidence-based approach, which takes into consideration the size of the infestation, the distance from the property and the potential risk of any damage.
RICS has called meetings of stakeholders and influencers to update its 2012 framework and ensure its policies reflect the most current research. The parliamentary committee has given the group until the end of the year to act.
It is also recommended the Law Society review the Property Information Form (which vendors have to fill in when selling) and the need to declare previous Japanese knotweed problems if they've been treated, by the end of the year.
