New advice for valuers aims to help sell homes with Japanese knotweed

Japanese knotweed breakthrough? New advice for valuers aims to help sell homes affected by the plant

  • Japanese knotweed can spread across land aggressively and destructively
  • The spread of the plant can be stopped – although it can be costly 

Japanese Knotweed can be an emotive phrase for anyone looking or trying to selling their home.

This is because it is something that can hold up – or even prevent – the sale of a property, even if the knotweed has been managed with treatment.

The plant can spread across land aggressively and destructively, and is notoriously difficult to get rid of.

Now new guidance has been issued by surveyors, which it is hoped will help homebuyers, homeowners and mortgage lenders when the plant threatens home sales.  

Japanese knotweed can spread across land aggressively and destructively, and is notoriously difficult to get rid of

The spread of the plant can be stopped – although it can be costly, at around £2,500 for a 10 sq m area for a herbicide treatment, or £5,000 for a 10 sq m area for an excavation.

Many mortgage lenders will lend on such properties if the plants are being treated and a guarantee can be provided.

However, it seems that further reassurance is required, and this is where new advice, which has been published for consultation, comes in. 

The advice comes from the Royal Institution of Chartered Surveyors and aims to support lenders and let homeowners proceed with affected property sales.

RICS wants to establish a management framework that outlines how sales can proceed, even where knotweed is found.

The new RICS guidance will give detailed industry guidance for lenders and valuers.

Philip Santo, the author of the new guidance, said: ‘Creating confidence and awareness that knotweed isn’t a death sentence for home sales is a key principle behind this guidance – it’s certainly not the ‘bogey plant’ that some make it out to be.

‘In most instances the weed can be remediated with effective treatment – so it’s critical that all those involved in the home buying and selling process have access to unbiased, factual information that sets out when they need to obtain reputable remediation services.’

RICS wants to establish a management framework thathelps

RICS wants to establish a management framework that helps sales proceed, even where Japanese knotweed is found

Nigel Sellars, of RICS, added: ‘We’ve launched this consultation ensuring the lending community, homebuyers and our chartered professionals get the opportunity to directly engage on how to dispel the myths and misconceptions, help unblock needlessly effected home sales and play our part in the built environment’s war on knotweed.

‘We will aim to publish a final version later this year, recognising how important it is to bring clarity to the marketplace as quickly as possible – particularly for those in need of help getting their property unstuck – and tackle knotweed with the latest expert advice.’


The new RICS guidance recommends that the current ‘seven metre rule’ – where a mortgage will not be offered if knotweed appears within that distance of a property – will be replaced with a framework that focuses on the actual effects Japanese knotweed is having at a property.

That framework considers whether damage is being caused by Japanese knotweed, and whether Japanese knotweed is simply present but not otherwise affecting anything.

The new process still allows valuers and surveyors to make a straightforward objective classification that will continue to provide a clear direction to lenders, sellers and homeowners, so that all parties understand what actions are appropriate.

Recommendations are framed around remediation and control of Japanese knotweed rather than focussing on eradication, but obtaining remediation advice from a reputable specialist organisation will still be appropriate in the most serious cases.

The difficulties caused by Japanese knotweed are acknowledged but it is hoped that the new guidance will lead to a more proportionate response when it is encountered.

Nic Seal, of Japanese knotweed specialists Environet UK, said: ‘It’s reassuring to see that RICS continues to recognise the very real risk the plant poses to homeowners and lenders.

‘RICS’ advice is cautious and sensible, while rightly recognising that in a vast majority of cases, Japanese knotweed is treatable with professional help – and with a management plan in place transactions should be able to proceed unhindered, with property values largely preserved. 

‘There are often good reasons to make eradication the goal – and by settling for ‘control’ the bar is lowered for the sake of a lower initial cost. 

‘Most homeowners and buyers will feel far less reassured knowing that knotweed is still present and alive on the property, even if herbicide treatment has induced it into temporary dormancy which could be broken at any time, particularly if building work takes place in the future, disturbing the ground and prompting the plant to regrow. This would have a far more serious impact on the value of the property over the long term, than if the infestation was eradicated from the outset.’

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