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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………………..

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.

im looking to purchase a house with JKW next door. The gentleman who owns the property next door is very old and is really unable to do anything with it. We wont be looking for a mortgage as we will be cash buyers, any advice ? My husband says definitely not, but I really want the house ? The estate agents informed us of it, but im wondering how bad can it really be ? Ive looked at pics etc, and read everything on here, but still unsure. House is a bargain anyway, and im thinking I could get it lower because of this. Any advice gratefully received

Hello Alison. A nice dilemma.

Someone will buy that house even if you don’t. The price might have to drop a bit but it will eventually sell, knotweed or not. Most people would probably say “leave it alone, there’s bound to be another house you’ll like as much on the market before too long”, but if I were in your shoes I would go for it – on the right terms. The sellers obviously know that they are sitting on a depreciating asset and must be expecting a reduced offer. However much of a bargain it seems to be at the asking price I would put in an offer at least ten percent lower and see the reaction. You can withdraw it and go lower if your offer is snapped up without demur. Don’t be frightened – they need you more than you need them [make sure you don’t overdo your liking of the house]. But you must go into this on the expectation that you will have to fork out for the removal of the JKW. Any offer is still subject to contract and can be withdrawn right up to that point [although you will be liable for your own legal and other expenses] so you should use the time after acceptance of your offer to talk to the man next door and see how amenable he would be to your taking full responsibility for eradication of the knotweed. A legal agreement with him might be helpful, entered into in a conciliatory manner with a view to being cooperative on both sides throughout. Some would suggest that you try to put a charge on his property for the expense of doing that but you need to be careful how hard you push, and anyway, if you get the right price with the seller, why upset someone who could be the way out of your dilemma? Of course, he might have no cares about the future resale value of his property, resent any interference, and be disinclined to go forward with you on that basis, in which case it probably would be better to walk away because JKW can, and will, only get worse and the surveyors’, valuers’and lenders’ antipathy to it will only harden.

I certainly think it would pay you to get a professional estimate of the cost of destroying your prospective neighbour’s knotweed and I think it would be reasonable to expect the sellers to deal with their neighbour along those lines in the first instance. If they won’t or can’t you might be able to persuade him. A professional report on the extent of the problem and the cost of a treatment plan will help both yourselves and the sellers in negotiating an acceptable price for the property. Please don’t get so carried way with desire for the property that you throw caution to the winds; there are plenty of houses on the market, nearly all of them without this problem. But if you can get the house you like, at the right price, with a solution to the problem within your overall budget, and end up with an amenable and grateful neighbour it is worth going for. If your husband still disagrees I think you should give him the benefit of the doubt and let this one go.

Makes the referendum question seem easy, doesn’t it?

Carl says:
7 July 2016

Just had a valuer come to value our property but because knotweed was found within 5 metres of my property , but not IN my property , they refused to proceed any further. I’ve been living here for 3 years with recent signs of it in my area and am now worried I’ll never be able to sell my house due to this problem. I don’t have 3/4/5 years to wait to eradicate it, I need to move on with my life , it’s absolutely appalling.

As long as you have a guarantee showing the knotweed is being treated/removed, it shouldn’t be a problem.

My partner and I are selling both of our houses and buying one together. We currently live on the next street to each other. My survey was fine but his has just come back stating JKW has been found within 20 meters. The only place we can think it might be is on some derelict land at the top of our streets; but then it would also be within 20m of my house too. It makes no sense why it would be picked up on one survey but not the other. We now have a very nervous wait as we have had an offer accepted on our dream home.

I can tell you from a first-hand experience…knotweed can and does kill a mortgage application. For help and advice, I would recommend contacting a specialist Japanese Knotweed removal company.