What is Japanese knotweed and how does it affect your mortgage?

What is Japanese knotweed and how does it affect your mortgage?

When buying a property, two words that you really don’t want to hear are ‘Japanese knotweed’. Not only is the property at risk of substantial damage if this plant is present but your mortgage application can be affected too. So what is Japanese knotweed and why is it such a problem?

What is Japanese knotweed?

Japanese knotweed is a herbaceous perennial that grows extremely quickly and aggressively. This invasive plant looks similar to bamboo with tall canes that can reach over 3 metres in height. It has large heart-shaped green leaves and produces clusters of creamy white flowers in summer. Able to grow in various environments, it spreads very quickly and forms dense thickets, smothering other plant life. However, it’s the roots that make Japanese knotweed a problem for properties.

Common issues caused by Japanese knotweed

The roots of Japanese knotweed can grow outwards by 7 metres and reach 2 metres deep. They are extremely strong and are able to penetrate concrete and tarmac. They cause brickwork to crack, break through property foundations as well as block and damage drains. As such, lenders are extremely wary of approving mortgages for properties found to have Japanese knotweed on the grounds or in the nearby vicinity.

Can you get a mortgage if there’s Japanese knotweed?

Whilst it can be more challenging to secure a mortgage for a property with Japanese knotweed, it is possible. Japanese knotweed is extremely hard to kill. This means that even if it looks as though the plant has disappeared, it’s usually lying dormant underneath the soil and will simply grow back. Even if a tiny piece of the root is still in the ground, the plant can start growing again. This issue, coupled with its destructive nature, makes lenders reluctant to provide loans for properties where Japanese knotweed has been detected on the grounds or nearby.

Each lender has their own criteria for this issue with some having more flexible policies than others. Some may refuse your mortgage application altogether. Others may charge you a higher interest rate, insist that you pay a higher deposit or stipulate conditions that must be adhered to. It also depends on the extent of the problem or potential problem and whether you can provide details of the treatment that’s being implemented.

In 2022, the Royal Institute of Chartered Surveyors (RICS) revised its guidelines for lenders relating to Japanese knotweed. These guidelines provide a less strict approach compared to the previous ones, which RICS now feels were excessively cautious.

Generally, if you can provide evidence that the Japanese knotweed is being correctly dealt with via a treatment plan that comes with an insurance-backed guarantee, a lender should be willing to approve your mortgage application.

Treatment options for Japanese knotweed

It’s important to use the services of a company specialising in the removal of Japanese knotweed. Trying to deal with it yourself can actually make the problem worse and cause it to spread. It’s also classified as a controlled waste. This means that it has to be disposed of at a licensed site. There are various ways to remove Japanese knotweed, either with or without the use of chemicals. The three main options are:

  • A herbicide treatment: This is the preferred method to treat Japanese knotweed as the herbicide gradually kills the plant. The treatment plan is slow as it can take years to kill the root system that’s underground. This is despite the fact that the plant may appear to be dead above the ground. However, the plant is sprayed at specific times during its growing stages to ensure that it is effectively killed off over time.
  • A root barrier: This is a physical membrane that helps to prevent the spread of Japanese knotweed. This containment method is often combined with other removal options. For example, a herbicide treatment or partial excavation of the plant.
  • Complete excavation of the plant: This is a much faster way to deal with the removal of Japanese knotweed than using a herbicide treatment. The entire plant is removed as well as the contaminated soil. All of the contaminated waste is then disposed of at a licenced landfill site.

Should you buy a property that has Japanese knotweed?

The presence of Japanese knotweed presents you with additional costs when buying a property. Therefore, you need to take these into account as they can be expensive. These costs include repairing any damage caused to the property, paying for a treatment method, higher insurance premiums as well as increased mortgage costs.

It’s essential to have a survey carried out to ascertain the extent of the problem before you proceed with the purchase. When relying on a mortgage to buy the property, the lender may require you to pay a larger deposit or higher interest rate. Your insurance provider may also charge you higher insurance premiums. This is because the presence of Japanese knotweed increases the risk of damage to the property.

When there’s evidence of Japanese knotweed, ask the seller if they’re already treating it and get proof of this. Alternatively, negotiate on the price of the property to cover the treatment costs carried out by a specialist Japanese knotweed removal company.

Even if the plant isn’t on the property grounds when you buy but is located nearby, it can spread very quickly to your property. This means that you’re potentially going to be faced with problems in the future, causing additional expenses. This may also affect you should you wish to remortgage further down the line.

Secure a mortgage when buying a property with Japanese knotweed

Our mortgage brokers know which lenders are prepared to offer loans for properties with Japanese knotweed and their criteria for this. As such, they can approach the right lenders and negotiate for the best deals on your behalf. Alternatively, you may prefer to take out a bridging loan to buy the property. This will enable you to deal with the Japanese knotweed before refinancing to a mortgage afterwards. Just give us a call on 01322 907 000 to discuss your options and get started.