Japanese knotweed growing in neighbours garden

5 key facts Estate Agents should know about Japanese knotweed

Finding Japanese knotweed on a property can halt a house sale.

Whilst there are various ways to get rid of this invasive perennial, if identification is left until the 11th hour of the sale, it can become a nightmare problem to deal with. There’s a legal duty on Estate Agents to disclose the presence of Japanese knotweed under CPR, so in our experience it’s best to be honest with the buyer to gain their trust which should make any transaction go through without a hitch.

We have highlighted the top 5 key facts we think all Estate Agents should know about Japanese knotweed. 

1. What knotweed looks like throughout the season

Japanese knotweed is a seasonal plant. In the summer, the luscious green leaves are surrounded by creamy-white flowers, over the winter the plant dies back leaving dead canes. It’s pretty easy to identify, and the buyer’s valuation surveyor will be looking out for it. We have a handy pocket sized Japanese knotweed identification guide, which we can send to you on request. This guide shows images of knotweed throughout the different seasons, as well as describing the key removal methods. 

2. What damage knotweed can do

The knotweed rhizome system can extend up to 3 metres laterally from the visible plant and up to 3 metres deep. If left unchecked, knotweed can cause damage to property, including foundations, walls, drains and hard surfaces, to name but a few. 

The RICS Information Paper sets a risk assessment framework for identifying the risk posed by Japanese knotweed in residential property. If there is any suggestion that knotweed might be present it’s a good idea to get the seller to commission a survey by a knotweed expert so that the risk level and recommended mitigation action can be determined. 

3. Japanese knotweed is an issue on neighbouring property

Risk adverse banks and building societies often refuse lending where knotweed is identified. What you might not realise is that they might also refuse a mortgage where knotweed is present on adjoining property, even though it’s not on the property being sold. Mortgages are usually available to properties with knotweed, as long as it’s being treated accordingly. This poses a particular dilemma for owners of property adjoining those with knotweed as they have no control over treatment in their neighbour’s garden.

The buyer may approach the neighbours about the situation, but bear in mind the neighbour may well not have the motivation to remove it. Remember it’s not illegal for them to have Japanese knotweed in their garden, as long as they don’t allow it to spread. 

4. What removal methods are available

The two main knotweed removal methods are herbicide treatment and physical removal. 

  • Herbicide Treatment is lower in cost but takes at least one growing season, often more. It’s the least disruptive method, but not suitable where there are plans that result in substantial disturbance of the the ground e.g. construction or landscaping works.
  • Physical Removal such as Environet’s Resi-dig-out™. This eco-innovative removal method can be completed any time of the year, and takes a matter of days. 

5. It’s not a good idea to hide the presence of knotweed

Whilst it may make the sale easier, the TA6 form now has a specific question about knotweed.  Concealing the presence of knotweed could prove to be an expensive mistake, as the buyer may have a case for misrepresentation and against the seller and report the acting agent to the authorities for breach of CPR regulations. 

As part of our consultancy services, we offer free telephone advice to Estate Agents. Please get in touch today on 01932 868 700

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