Japanese knotweed, or fallopian japonica, has been around in the UK since the 19th century, with Victorian gardeners admiring its heart shaped leaves and delicate flowers. The plant also found favour with builders of the newly expanding railways, who appreciated its hardiness.  

However, the plant has no natural predators in the UK, and combined with the speed of the plant’s growth it soon spread quickly.  The Environment Agency now describe Japanese knotweed as “indisputably the UK’s most aggressive, destructive and invasive plant”. The plant can grow up to 4 meters in 10 weeks. Most worryingly for homeowners, roots can spread out up to 7 meters and undermine the structure of nearby buildings or block drains. 

While it’s not illegal to have Japanese knotweed on a property, homeowners are required to aim to control it.  An amendment to the Anti-social Behaviour, Crime and Policing Act 2014 means that property owners could be prosecuted if they fail to do this. 

As you’ll have already realised Japanese knotweed can be quite destructive to the buildings around it, and this is the prime reason why lenders are reluctant to lend to people buying properties with Japanese knotweed present.  

As the plant grows it can break open cracks in foundations or walls, and damage or block sewage or drainage works. 

It can also lie dormant, when it appears to have been destroyed, reawakening in the event of construction work, such as building an extension or laying a patio. Worse still, the chances are that any damage won’t be covered by buildings insurance. 

With all these negatives it’s easy to see why lenders may be reluctant to give a home loan to someone buying a house with Japanese knotweed. But all may not be lost.

While lenders have their own criteria to assess the risk posed by Japanese Knotweed, they are broadly based on the categories outlined by the Royal Institution of Chartered Surveyors (RICS).These are graded 1-4, with 4 being the most severe. The risk factors are as follows:

1. No Japanese knotweed seen on the property itself. However, it can be seen on a neighbouring property or land more than 7 metres away from the boundary.

2. No Japanese knotweed seen on the property. However, it was seen on a neighbouring property or land. Here it was within 7 metres of the boundary but more than 7 metres from habitable spaces, conservatory and/or the garage of the property surveyed. 

3. Japanese knotweed is present within the boundaries but more than 7 metres from habitable spaces, conservatory and/or the garage of the property surveyed. If there is any damage to outbuildings etc, this is minor 

4. Japanese knotweed is within 7 metres of the habitable space, conservatory and/or garage, either within the boundaries of the subject property, or in a neighbouring property or space. AND/OR Japanese knotweed is causing major damage to outbuildings, drains, associated structures etc.

If the risk factor falls into category 3 or 4 then further investigation by a suitably qualified or experienced person will be necessary. 

Our specialist mortgage brokers work with a range of lenders who we know will consider lending to buyers seeking to purchase a property that has Japanese knotweed either on-site or nearby. 

The lenders we work with have a range of criteria, although there are some general rules. If the Japanese knotweed at the property you want to buy falls into category 1 or 2 you may find that you will only be approved for a lower Loan-to-Value (LTV) mortgage, meaning that you will be required to find a larger deposit. 

For properties with a risk factor of 3 or 4 the picture is slightly different. Lenders will want the property inspected by a specialist. They may want a treatment plan put together or ask for it to be removed – although they are unlikely to require complete eradication. Lenders may require that all work is backed by insurance. 

We can help to reassure you that the presence of Japanese knotweed doesn’t need to mean the end of your house purchase, as we understand the different policies of different lenders. Helping you to find the right one for your individual circumstances and the level of Japanese knotweed on the property.

It may not always be simple to get a mortgage on a property with Japanese knotweed, but Simply Lending can make sure it isn’t impossible.