Selling a House with Japanese Knotweed

How to identify, how it spreads and what you can do to eradicate it

Stress, stress ... stress!

It’s stressful enough selling a property.

If you’re a property developer you’ll take that stress in your stride. If you’re not, and you’re just looking to sell a home, then you will know the stress and strain that the process throws up.

Believe it or not, there are also other aspects of selling property that can be incredibly draining.

If you’re in a position where you’re selling property and you’ve a Japanese Knotweed problem, you’re quite possibly in for a rough ride. Japanese Knotweed is a big deal and it’s causing a number of house sales to fall through.

We'll take a look at the problem, and see what can be done about it.


So, what is Japanese Knotweed?

If you have it on your property, you'll know what it is.

Japanese Knotweed, scientifically known as Fallopia japonica, is basically a highly invasive type of weed that grows thickly and deeply. It, like most weeds, is unsightly, but the main reason it causes so many problems in gardens is that it has such a ferocious rate of growth.

If left unmanaged for even a season, it will take over much of a garden space. It is for this reason that so many homes and properties are now proving difficult to sell. Obviously, being a plant, Japanese Knotweed has different looks throughout the year as the growth cycle continues through the seasons.

There are a couple things you can look out for when you are staring at the weeds that are taking over your garden. Of course, they may not be Japanese Knotweed, which is a good thing.

Watch: How To Identify Japanese Knotweed

Date of bloom

Around mid-March Knotweed begins to show itself.

Colours and textures to look out for

  • It’s shoots are very distinctive, with red and purple showing through as colours
  • As it passes through the year the stem begins to look like Bamboo and there are large leaves to the plant
  • White flowers are clearly visible before the Autumn
  • Leaves shaped like a shovel

How does Japanese Knotweed spread?

Japanese Knotweed spreads very easily and this is the key problem with the weed.

Fragments and stems of a Knotweed can easily take root if dispersed around a garden. If someone tries to cut the Knotweed or get rid of it in any physical way this can lead to fragments falling to the ground. In soil, the Knotweed will quickly take root. In fact, it really only needs a tiny piece or fragment of the plant to take root and then the cycle of growth will start again.

It can also be transported on a shoe, for example, or an item of clothing. This is important to remember because,

If you do discover Japanese Knotweed in your garden, don’t attempt to get rid of it but instead prevent access to it. This allows efforts made to contain and/or eradicate it. Essentially, if Japanese Knotweed is found on a property, it should be left alone until a clear plan has been made to eradicate it. The ease of taking root means that first of all it’s best to try and contain it.


What does Japanese Knotweed do?

It’s quite a significant amount of damage. In fact, houses with a Japanese Knotweed infestation could well present as serious problems for years to come.

Selling a House with Japanese Knotweed

  • The biggest issue around Knotweed is its ability to enter cracks and other breaks in surfaces that are usually quite resilient. This is why Japanese Knotweed often gets into pavements and paving stones, as well as the brick work of buildings.
  • In the UK, Japanese Knotweed is so invasive that it has become a legal matter. If someone plants it on purpose in the wild they will face a considerable financial penalty of up to £5,000 or a prison term up to 2 years. This shows just how damaging the plant can be.
  • However, the biggest issue is in urban areas, where Knotweed can affect infrastructure. If it is present on your plot, there is a very good chance it can devalue your property. Buyers are more aware now of the problem Japanese Knotweed causes, and the difficulties that are presented when trying to get rid of it.
  • One key area of damage that a property can see can be found in pipes. We all know that pipes are important around a property, and that they need to be kept clear. If it grows in your waste pipes, for example, you have a situation where a drain run can be obstructed. This can be catastrophic, and can lead to a property owner having to replace a drainage system.
  • A property that has retaining walls can find that the walls have been infiltrated by Japanese Knotweed. The sheer impact of having a heavy Knotweed growth in a retaining wall can literally mean a wall can suddenly collapse.

Read: 3 Common Drainage Problems That Will Affect Your House


How can Japanese Knotweed be dealt with?

There are a number of ways in which Japanese Knotweed can be managed. Each of these has some effect, but in some cases a specialist removal team will need to be involved.

  1. Cutting. The obvious response is to cut the weed. This rids the space of the visual aspect, but as with most weeds this does nothing in the long term. You won't have dealt with the roots by doing this, so the Knotweed will continue to grow and thrive.
  2. Herbicide. Can be used, but this is to be managed by a professional contractor. Be ready, also, for the possibility that it can’t be used. This is to do with the location of the property that is to be treated. If it is near wildlife, for example, or a protected scenic area, there is a very good chance that herbicides will not be permitted.
  3. Burning. It has been common practice recently for gardeners to burn waste. This is just like the cutting strategy mentioned earlier in the article. Burning will do a very good job of getting rid of the surface materials, but will make no difference below that surface. So Japanese Knotweed will simply reappear
  4. Burying Knotweed. a recognised technique to help get rid of it. This actually makes sense in a way, because by having the various fragments of the weed underground, it is out of sight. Then it should simply be a question of making sure it never gets to go above ground. Special equipment, such as a root barrier membrane, will have to be used, but as long as all elements are carefully managed, you should have the weed buried and not causing harm for some time. This process does take considerable effort to organise, but it is a way of getting rid of the problem.
  5. A Bund. Can be used in the garden to get rid of the Japanese Knotweed. This process does take a considerable amount of time and organisation is key. However, if it is used, it does mean that you can safely dispose of the weed in a secure part of the garden.

Selling a home with Knotweed

There are numerous examples of people finding it challenging, if not impossible, to sell a home because of Japanese Knotweed.

There are even examples of people not being able to sell a property because the building next door has Knotweed. This becomes a very emotional situation, and the following advice should help you negotiate the problem a lot quicker.

The neighbours

One particularly distressing aspect of Japanese Knotweed is its ability to spread, and people are finding that they cannot sell their property because of Japanese Knotweed being rampant next door. Remember that this weed can infiltrate concrete and you’ll understand why people may not want to move in somewhere that has housed Japanese Knotweed.

Mortgage worries

On top of that, and even more worryingly, people are finding that they cannot acquire a second mortgage or remortgage their property, because Japanese Knotweed is nearby or is part of their property. It is a serious issue, and unless a clear solution is presented to a property owner, it can result in the owner being trapped in a property, unable to sell.

The big reason for all of this is the ability for Japanese Knotweed to go deep underground and spread quickly. There have been cases where Knotweed has attacked the foundations of a property, therefore making it difficult for the property to be anything but a liability.

Take a Read: What Makes an Unmortgageable Property? (And How You Can Fix It)

Make a plan

Some lenders have demanded that sellers gain professional support, and have an eradication plan in place so the problem can be solved by experts. Many lenders actually ask that there is a 10-year guarantee from any company that eradicates Knotweed, so that the property is see as being safe and clear.

The long and the short of it is that Japanese Knotweed, even if it is in a field within short walking distance (a few metres) from your home, can be the reason you don't get a mortgage.

While this is a major problem for many homeowners as well as owners of property, it doesn’t mean that there is no way out. Short of getting rid of the problem yourself, it is common practice for a property owner to pay for a specialist professional to come in and deal with the problem.

Turn to the professionals

Firstly, if you discover that your home has a problem with Knotweed, don't try and deal with it yourself. Even if you get down on your hands and knees and try to cut it or bury it, it is still a much better idea to hire professionals to do the job.

It really isn't possible, without some specialist equipment, to get rid of the stuff. Japanese Knotweed has been known to survive in temperatures of -17 degrees.

Cost of Japanese Knotweed removal

At the same time, having a professional team in to get rid of the Japanese Knotweed is expensive. An average Japanese Knotweed removal cost, and we’re not considering huge jobs, is around £3,000. This kind of price can be quoted to you even if the problem is next door’s!

Another option is to sell your house fast to a cash home buyer. This does not, in this circumstance, mean a private buyer. Instead, it means a company that buys property commercially, with a view to reselling it at a later time.

A good quality cash home buyer company will be able value your house and then apply the necessary work to ensure that the property is made ready to sell. They will most likely ensure that all of the costs are included in the quote they give. In any case, the benefit here is that there will be no issue with taking the property off your hands because they have no mortgage to pay.

This allows you to get on with the process of buying another property to live in. Whichever way you choose to deal with Japanese Knotweed, it’s important to bear in mind that lenders aren’t lending against property that has Japanese Knotweed (even if it is a few metres away). Also buyers won’t take the property because it has a lower value already, as they see the depreciation effect over time.

Whatever you do, don't let the problem linger. If left to its own devices, Japanese Knotweed can make a house virtually impossible to sell. Act fast, and ensure you find a buyer who is able to take the property off your hands quickly.

Read: Tips to Revamp Your Garden When Selling Your House