/ Home & Energy

Are weeds killing your mortgage chances?

The list of plant nightmares for your house can be quite extensive. And now some people are finding they can’t get a mortgage if Japanese knotweed has been found in their garden or even close to the property.

There are Leylandii conifers that block out your light, ivy plants pulling out your mortar and tree roots clogging up your drains. But Japanese knotweed is the one to watch out for.

Japanese knotweed looks a bit like bamboo or dogwood. It’s hardy, perennial (it lives for more than two years), and can grow to over two metres tall. It was introduced to the UK in the mid-19th century and, because it’s invasive, difficult to kill and nothing really eats it, it’s now widespread.

Weeding out the issue

Keen gardeners will know all about dealing with difficult weeds such as bindweed and ivy – but Japanese knotweed is devilish to get rid of. The Royal Horticultural Society even calls it a ‘thug’!

The creeping roots of the Japanese knotweed are extremely difficult to eradicate and it can grow back from just a centimetre of root. However, it can be killed by repeated treatment over several years with the strong weedkiller glyphosate.

If you call in the professionals it can be a very expensive job – the Royal Institution of Chartered Surveyors (RICS) estimates it can cost up to £5,000 to use other techniques like root barriers to stop it spreading while the weedkiller is working. If the knotweed is creeping in from nearby land, you’ll need a co-ordinated attack.

But what damage does it do to your house? The guidance from RICS talks about drains getting blocked by roots, patio slabs being disrupted, and buildings with shallow foundations (like garages, sheds and conservatories) being undermined. It says that more dramatic damage to buildings is very rare and exceptional.

Knot a problem?

So is Japanese knotweed a big problem when it comes to selling your house? You may have read about Peter Gingell over the weekend, whose house sale fell apart when his buyers discovered Japanese knotweed in his garden. Some mortgage lenders are even turning down mortgage applications on properties where knotweed is present.

So even if Japanese knotweed can really cause uninsurable structural problems, surely a blanket ‘no’ policy to mortgage lending isn’t the best solution? Our mortgages expert Marie Kemplay says:

‘The situation regarding knotweed is quite confusing, and although organisations like RICS have produced guidance for mortgage lenders, there are no clear cut rules. Some lenders will not offer mortgages if Japanese knotwood is present on your land whilst others will consider it providing there are some guarantees in place.

‘But one general piece of advice is, no matter how tempting, not to just rip it out of the ground yourself. You need to get professionals in otherwise you may find it difficult to prove you have taken appropriate action to get rid of the problem.’

Have you had any plant problems with your house? Would finding Japanese knotweed in the garden put you off a purchase?


Another “plant of hate”, in the USA at least, is Kudzu, also from Japan and east Asia.


However it has its uses as well, as the link explains. It is very good at nitrogen fixation, which means it is a plant that adds fertiliser to the soil rather than the other way round, and can be used as animal feedstock.

The ease with which it propagates could well find that it has a use for the mortgage profession as well, in order to raise the stress for those needing a loan. It will also help them to enable specialist gardeners to charge hundreds of times their usual wages for its removal. It will benefit the government’s VAT take on services that in reality add very little value.


I have had a similar issue with NatWest with knot weed found on a neighboring property. The valuer classified it as a category 2 per RICS guidelines which per Barclays/Woolwich lending criteria needs no further action but NatWest requires an investigation which of course runs into the thousands of pounds even though the specialist firm can do exactly the same treatment for a few hundred pounds if the Bank was not involved. I fully accept Banks should be careful with their lending but there must be a balance with being fair to their customers needs too. Is Which planning on doing anything ?


6 months ago my partner and I bought a property that has been surveyed as having JKW in the front garden. We have an insurance backed treatment program in place (paid for by the vendor) and the only people who would (and have) lend to us were Halifax. We’d started off with HSBC so it’s cost us two lots of fees / valuations etc. AND, the twist in the tail is that it isn’t knotweed!!! So we’re now waiting for confirmation of that fact, and then see if there’s anything we can do to claim back our costs from the knotweed firm which were in fact completely unnecessary!!!!


We have found our dream home and after putting in an offer and getting it accepted the estate agent casually said ‘did we mention the JK?’ We are devastated and not sure whether to go ahead with the purchase or not, indeed it may not be in our hands should the lenders refuse to give us a mortgage.

The Estate agents have sent us copies of the treatment plan, paid for by the vendor and they insist this is nothing to worry about! We called the company treating the JK and they said that although it’s in 3 separate places, it’s a small amount and will be straightforward to treat.

Would you buy the house? Put in a lower offer? If so how low? Or run a mile?


Hi KD, we have some advice on property haggling here (http://www.which.co.uk/money/mortgages-and-property/guides/buying-a-house/making-an-offer-on-a-house-or-flat/) which may be of some use to you.

It’s probably worth seeking a quote from specialist in Japanese Knotweed to help you in your decision and negotiations.


Hello KD – I would withdraw the offer, get the sellers to carry out the treatment plan at their expense, and possibly make a new offer at 10% below the original asking price [subject to survey and mortgage approval] if you still felt comfortable with buying the house. If you have already paid [or agreed to pay] a mortgage arrangement fee see if you can get the sellers to reimburse it. Also it would be advisable to check the insurability of the property and whether or not the premium would be loaded. There is no doubt that the estate agent should have brought the presence of the Japanese Knotweed to the attention of prospective purchasers since they were clearly aware of it. An interesting question to them would be what part it played in their valuation of the property.

Can you be sure that the treatment of the existing Japanese Knotweed will be permanent and that a further outcrop might not appear? – see if there is any in neighbouring gardens or areas from which it could spread. It says in the Intro that it needs repeated treatment over several years – are you content with that? And do you mind the property being ‘blighted’ for such a period? Disappointing though it might be, don’t be afraid to walk away from the purchase. If you do receive satisfactory assurances and acceptance of a revised offer you can still withdraw right up to exchange of contracts [although you would be liable for any legal costs incurred on your side]. Don’t be worried about another prospective purchaser coming in with a higher bid; the chances are that the estate agent will have to be much more upfront about the existence of the JK if the property goes back on the market and that will inhibit stronger interest. Sellers can’t honestly cover-up the presence of JK in a house sale because it is specifically declarable in the Property Information Form and therefore part of the Contract; you would be bound by that too if you proceeded to purchase and subsequently wished to sell. Even at a lower price a ‘dream home’ might have an irradicable blemish and on balance you might be better off leaving it to someone else to worry about while you pursue your quest for a nice new home – they do exist.


I’m probably going to get throttled here
We have a huge garden of JK growing on the next property down the lane………………It does not belong to us
It became so big that the silage trailers were carrying it up our way……………..I have successfully gotten rid of it on three occasions but to say its difficult is an understatement………….
The railways and Roads authorities have a herbicide that they use that we cannot get……………unfortunately………..
I cannot understand when such an invasive species is known about why our great and good do not legislate that the owners have to eradicate the problem……………….Why can this plant be allowed to simply grow where it pleases………………..

Tatter says:
23 May 2016

I’ve just had a buyer pull out because Japanese Knotweed is growing 80 metres away from my property!

The area it is growing in is a communal area managed by the residents managing agents and has spread from land owned by Northern Rail.

I’ve had my house on the market for two years and was about to exchange contracts, I’m absolutely livid!

As soon as Japanese Knotweed is mentioned people run a mile, which is ridiculous as this IS treatable and often not the problem of the buyer or lender.