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Original poster

To ask how you deal with Japanese knotweed

63 replies

rogertherabbit · 14/05/2017 10:09

Hi all, I post a couple of weeks ago about a house I've fallen in love with but it was quite near a main road. This turns out not to be an issue, but I've now discovered there is knotweed in the garden! It's not near the house and is being treated, but I'm looking for your experiences of dealing with this stuff - there is apparently a 10 year plan in place, but I don't really know how much of an issue it'll be. Plus I don't know if the bank will give me a mortgage 😟 Hoping with the treatment plan they will, but I just don't know!

OP posts:
RedBugMug · 14/05/2017 10:13

if it's being treated it's no problem.
professional treatment plan doesn't bother most banks either.
but where does it come from? if from an untreated area nearby (council park, rail line?) there is no chance eliminating it.

Original poster
rogertherabbit · 14/05/2017 10:29

Not really sure, there's a church next to the house and there is some in the grounds, I think. I guess that would need to be treated too....

OP posts:
Grilledaubergines · 14/05/2017 10:31

As long as it's eradicated prior to exchange of contracts, I'd go ahead if me. But it can affect your home insurance premium. It's a bastard to deal with.

Reow · 14/05/2017 10:31

We ended up pulling out from a house we'd offered on because of it. It was also next to a church on a main road.

It's not in a village starting with a C is it?

KarmaNoMore · 14/05/2017 10:34

This reply has been deleted

Message withdrawn at poster's request.

Original poster
rogertherabbit · 14/05/2017 10:34

Reow no it doesn't start with a C, sounds similar though! It's so hard because I love the house - it's perfect in so many ways

OP posts:
KarmaNoMore · 14/05/2017 10:43

This reply has been deleted

Message withdrawn at poster's request.

MaisyPops · 14/05/2017 10:45

I'd probably be pulling out because even if it gets sorted on the property if there's anything elsewhere on neighbouring sites it will just come back.
It's horrible stuff.

Call me a cynic but that might be why the current owners are leaving.

Frillyhorseyknickers · 14/05/2017 10:49

You can't usually get a mortgage on a property with knotweed in situ.

Whatever you can see is really the tip of the iceberg and the soil it has been growing in is required to be treated as contaminated waste, as per asbestos. It costs thousands of pounds to kill and the soil is contaminated for 20years post treatment.

I'm a surveyor by profession and even at 20% lower than market value I would not purchase anything with knotweed on. I spend weeks of my life working with issues it causes.

JeNeSuisPasVotreMiel · 14/05/2017 10:50

Post here for expert advice....www.mumsnet.com/Talk/gardening

KarmaNoMore · 14/05/2017 10:57

This reply has been deleted

Message withdrawn at poster's request.

missm0use · 14/05/2017 11:00

The current home owners will have to sort the issue out before they sell. If there is Japanese knotweed on the homeowners report then the new buyers will never be able to get a mortgage, as Japanese knotweeds roots can grow so deep that they can damage the foundations of buildings! They only'll way they'll sell is if it's a cash buyer - I know because we were in the process of buying a house last year and had the same issue.

herethereandeverywhere · 14/05/2017 11:02

Unless there is a large and uncontrolled problem on adjoining land it wouldn't put me off.

We found some in our garden after buying our house (grateful my dad knew what it was!) it had come from a small clump in the neighbouring garden. Spoke to neighbours and we both treated. It was gone in 1 'season' (takes a year to check whether any will grow back).

I've also seen successful eradication in the front gardens of an entire terrace where it took hold (spread from primary clump growing under fences and up through gaps in paving stones). Again gone in a treatment over a year. And friends who eradicated from their garden in a season after actually nurturing and moving the beast of a plant before they realised what it was!

I would definitely buy unless it was one of these 2 scenarios:

  1. House is new build/nearly new. Could be the ground was infested and not properly treated before building on the site. Avoid, eradication is very difficult in this situation.
  1. House adjacent to land where knotweed is prevalent and out of control. Railway lines, scrapyards, abandoned property would be good examples. If the church you mentioned is occupied and has its grounds maintained I'd speak to the church about their knotweed problem to understand whether they have an eradication plan in place and if not encourage them to do so.
herethereandeverywhere · 14/05/2017 11:11

Frilly's advice is a massive overreaction unless the knotweed is established and substantial in size. There are professional outfits who will eradicate (including removal of the contaminated soil so you won't have to do anything more via a vis the 20 year rule). Find the businesses that do this and get their advice/quote. I think we were quoted £2k-£2.5k.

It is only a problem if it is left uncontrolled by the neighbouring site or was in land which was built on. Scaremongering about isolated patches is really unhelpful as no one treats them and they become larger and less easy to eradicate.

BarbarianMum · 14/05/2017 11:18

God everyone, calm down. It's knotweed, not a triffid.

OP how much is in your garden? The best way to treat knotweed is to inject the stems with glyphosate each August. This treatment will need to be done every year for 5- 10 years. The injector gun costs about £100 and glyphosate is about £10 a bottle. Each stem gets a few cc.

If there is a few square metres worth on your land (less than 5) then I'd say its perfectly doable if the adjacent patch is also being treated. More than that and id hesitate.

Frillyhorseyknickers · 14/05/2017 11:18

It isn't uncommon for the rhizomes to go to 3m below the surface soil - they penetrate clays and subsoil strata's and find weaknesses in foundations- the amount of damage caused by a "small amount" of knotweed can cost several thousands of pounds to address.

Knotweed is an invader and it's successful as it is a vegatitive regenerator - it can regenerate from a tiny amount of leaf or stem. Meaning that if a previous homeowner has cut down unknowingly and composted, there may already be other rhizomes present that are not visible.

Honestly, unless you are getting the bargain of the century and are a cash buyer, I would not touch it with a shitty stick.

BarbarianMum · 14/05/2017 11:21

The depth isn't a problem, unless you're right up against a building, or stupid enough to try and dig it out. Glyphosate is translocated throughout the plant so will kill the roots/rhizomes too.

Frillyhorseyknickers · 14/05/2017 11:22

I suppose this thread is testament to why you shouldn't take advice off of the internet - there are a lot of lax attitudes and misinformation on here regarding knotweed.

I'm a chartered surveyor and I do a lot of valuation work on property with knotweed - I do actually know what I'm talking about.

BarbarianMum · 14/05/2017 11:26

Mmm, I'm a nature reserve manager and actually treat knotweed as part of my job. On year 3 with the current patch which has shrunk by about 60%.

llangennith · 14/05/2017 11:36

Don't buy! I took up the crazy paving in my tiny front garden that had been there for over 40 years and within weeks it was filled with bindweed. It had lain dormant under the slabs all that time just waiting for a bit of light so it could break out.
No amount of weedkiller or weeding eradicated it. I had to accept that I could just about control it by constant weeding.

fanfrickintastic · 14/05/2017 11:45

We bought a house with active growing, untreated knotweed. No issues on the survey or getting a mortgage. We left it until it got close to the house (it was in the front garden) then had it treated using the serious chemicals by a proper company. They came back every year to check it wasn't growing back then after 3 years issued an iradication certificate and a 10 year guarantee. Cost £400 plus vat to deal with. We've since sold that house and didn't have any issues.

It certainly wouldn't put me off.

thenorthernluce · 14/05/2017 11:48

Walk away, OP. We walked away from two property purchases last year when Knotweed was discovered and we are so relieved we did. Your solicitor must inform your mortgage lender about the presence of Knotweed and they will decide whether to lend. Most won't. Plus, if the infestation is not contained on the property boundary (e.g. on neighbouring land, common land etc), you are not in control of the treatment plan and this runs the risk of failure.

Put this place out of your mind and move on. Caveat emptor.

Original poster
rogertherabbit · 14/05/2017 11:52

There are two quite small patches on the property according to the report, I would post a picture but it's not my report so don't want to break any rules or potential identify the vendor. Neither patch is near the house, but I understand it can travel underground

OP posts:
stuntcamel · 14/05/2017 11:58

A friend of mine was renting a house a few years ago. There was knotweed in the garden and one day, they discovered some growing up through the middle of their living room floor. It had forced its way up through the concrete foundations.

SilverLegoBrick · 14/05/2017 12:02

I live in France and there's knotweed everywhere. No one is bothered. Why isn't there huge hysteria here (genuinely wondering)??