Japanes Knotweed

koolpc · 31 Oct 2019 at 22:14

Friend of mine is buying house which has Japanese Knotweed growing behind the rear fence of the property. Quite a very large sway of it.

Apparently the vendors had a specialist firm in to survey and treat the knotweed with a 5 year management plan and 10 year guarantee. My friend has seen the survey etc.

Banks etc are willing to lend if someone takes out one of these managed / guarantee plans.

The garden has no knotweed (yet!).

Anyone here had knotweed issues?

Obviously it didnt stop him from buying even though the knotweed is covering a very large area behind all the gardens in the street.

Rannoch · 31 Oct 2019 at 22:23

I had it at the back of a rented property a few years back, it grew hard and fast, came through a stone wall at one point.

koolpc · 31 Oct 2019 at 22:47

Vargas said:
I had it at the back of a rented property a few years back, it grew hard and fast, came through a stone wall at one point.

Wasnt it ever treated?

The_Abyss · 31 Oct 2019 at 22:52

I'd venture that if the knotweed is growing in large swathes then it isn't being effectively managed. You can't keep it at bay - it needs to be removed and destroyed.

It is increasingly prevalent, but I don't think I'd bother with it and instead would just look elsewhere.

Rannoch · 31 Oct 2019 at 22:57

We were only in the property from March until October. It was on farmland and owner advised us to leave it, he was worried that we could spread it accidentally.

koolpc · 31 Oct 2019 at 23:00

The_Abyss said:
I'd venture that if the knotweed is growing in large swathes then it isn't being effectively managed. You can't keep it at bay - it needs to be removed and destroyed.

It is increasingly prevalent, but I don't think I'd bother with it and instead would just look elsewhere.

I went to look at the property and it is a massive area of knotweed but, nothing in the gardens. Looks like it is being managed directly behind the property but not elsewhere. I guess the 5 year plan and guarantee are good to have if selling though as most lenders require that where knotweed is prevalent.

koolpc · 31 Oct 2019 at 23:01

Vargas said:
We were only in the property from March until October. It was on farmland and owner advised us to leave it, he was worried that we could spread it accidentally.

Thats true. People cut it and the bits they cut, if dropped on soil etc can set root.

The_Abyss · 31 Oct 2019 at 23:03

It sounds like they're good to have to sell the property but not to maintain it. The roots extend for several metres outward away from the plants, so they will be coming towards the actual building. It should not be left 'managed' - it needs to be eradicated.

Rannoch · 31 Oct 2019 at 23:03

koolpc said:
Thats true. People cut it and the bits they cut, if dropped on soil etc can set root.

I was surprised how fast it grew, if I owned the property we rented I would be worried.

koolpc · 31 Oct 2019 at 23:05

The_Abyss said:
It sounds like they're good to have to sell the property but not to maintain it. The roots extend for several metres outward away from the plants, so they will be coming towards the actual building. It should not be left 'managed' - it needs to be eradicated.

Managed means just that. Its a 5 year plan of eradicating it. Problem though is that the whole area needs to be done to have any effect.

The_Abyss · 31 Oct 2019 at 23:10

Exactly, and something about this doesn't sound right. It is behind houses on a street with other houses, but the vendor of this house is the one that took action? It feels odd that there wasn't a collective action taken place. Why is one house, the vendor, taking total responsibility to remove it - it will affect everyone.

It just sounds like the management plan is 'keep it out of our garden for 10 years', which is pointless.

koolpc · 31 Oct 2019 at 23:12

The_Abyss said:
Exactly, and something about this doesn't sound right. It is behind houses on a street with other houses, but the vendor of this house is the one that took action? It feels odd that there wasn't a collective action taken place. Why is one house, the vendor, taking total responsibility to remove it - it will affect everyone.

It just sounds like the management plan is 'keep it out of our garden for 10 years', which is pointless.

I agree. I think neighbour to the right is doing the same. Other houses are rented i believe.

rubberduck · 31 Oct 2019 at 23:15

Massive amounts of scaremongering and misinformation related to Japanese knotweed. It's not nearly as much of an issue as many would have you believe

MissChief · 31 Oct 2019 at 23:22

rubberduck said:
Massive amounts of scaremongering and misinformation related to Japanese knotweed. It's not nearly as much of an issue as many would have you believe

It's best to use official guidance which states it can take up to 3 years to fully eradicate it.

koolpc · 31 Oct 2019 at 23:37

MissChief said:
It's best to use official guidance which states it can take up to 3 years to fully eradicate it.

Very true. The house friend is buying has a 5 year plan in place. Only issue is that its only a small area of the 'infestation'. I guess its enough to keep his property clear. Rear of the garden is approx 100ft from the house.

Funky-Melon · 1 Nov 2019 at 07:59

The management plan doesn't actually get rid of it, it eradicates the surface plant but deep down the root enzymes are still there, the guarantee is so if it comes back they will come back out and sort it again - it's never truly gone.

This is straight from a specialists mouth. I've done a huge amount of reading on this, I had to pull out of a house purchase earlier this year as it had japanese knotweed in the garden. I wasn't initially put off till I got a survey report from a specialist. The only real way to completely be rid of it with no risk of coming back is to excavate the land and put new soil in - very expensive.

Things to be wary of...
- It can lie dormant for a very long time
- Only takes a tiny amount to come back again
- It is extremely destructive
- You're not aloud to dig in your own garden, even with a management plan due to potential soil cross contamination
- You're not allowed to dig it up/dispose of it yourself in regular garden waste either

It also puts a marker on the properly, the house we were looking to buy was priced at £235k when others of a similar size on the street were £250-260k. After I pulled out in April it finally sold last month for £210k

EDIT: It's bad enough if it's on your mates property but at least, if they're happy with a management plan, they can get one.

If the neighbours are not bothered/not very nice people then they're going to have a hard time getting anything done about it, without going down the legal route.

BUDFORCE · 1 Nov 2019 at 08:11

Funky-Melon said:
The management plan doesn't actually get rid of it, it eradicates the surface plant but deep down the root enzymes are still there, the guarantee is so if it comes back they will come back out and sort it again - it's never truly gone.

This is straight from a specialists mouth. I've done a huge amount of reading on this, I had to pull out of a house purchase earlier this year as it had japanese knotweed in the garden. I wasn't initially put off till I got a survey report from a specialist. The only real way to completely be rid of it with no risk of coming back is to excavate the land and put new soil in - very expensive.

Things to be wary of...
- It can lie dormant for a very long time
- Only takes a tiny amount to come back again
- It is extremely destructive
- You're not aloud to dig in your own garden, even with a management plan due to potential soil cross contamination
- You're not allowed to dig it up/dispose of it yourself in regular garden waste either

It also puts a marker on the properly, the house we were looking to buy was priced at £235k when others of a similar size on the street were £250-260k. After I pulled out in April it finally sold last month for £210k

This, I am a mortgage underwriter and look at valuation reports and occasionally the knotweed reports. They only way to get rid of it as you say is to dig up the ground. If it's in a neighbours property, you can't really do that, so it'll just keep coming back, it will lower the value of your house and dependent on the severity mortgage lenders will decline an application for it.

rubberduck said:
Massive amounts of scaremongering and misinformation related to Japanese knotweed. It's not nearly as much of an issue as many would have you believe

That's just at terrible advice

psd99 · 1 Nov 2019 at 08:15

https://www.youtube.com/watch?v=Yu-Y68W4K5Y&t=13s - just look at what it'll do if it got to your mates property

how far away is the knot weed?

SeatIbiza · 1 Nov 2019 at 09:14

BUDFORCE said:
That's just at terrible advice

It actually isn't. There is a lot of misconception about JKW. Like the video posted by psd99. JKW rhizomes are soft, they will exploit cracks/holes in property/concrete/foundations but they cannot physically damage property due to their soft nature. If you've ever touched one you will know you can bend it with ease. Tree roots on the other hand, are hard and WILL cause structural issues yet people grow these feet from their houses.

For mortgage purposes you'll need a KMP in place with an appropriate insurance backed guarantee. I use www.japaneseknotweed.co.uk at work who are treating around 25 of our sites with JKW (usually around £1,500+VAT each for the plan). I've had it completely removed by another firm from a site in Birmingham and that cost us £27kish. They use a slightly cheaper method vs "dig and dump" using a sifting machine so that soil is retained on site rather than taken away and all treated as contaminated waste (they did a lot of the work on the 2012 Olympics site) - they are Environet UK.

On a KMP all they use (usually) is Roundup ProVantage (~£50 on ebay for 5l) and spray it a couple of times a year with a knapsack sprayer; I have a tub in my garage. The key is to make sure it's a healthy plant to begin with so that the poison gets into the rhizome system. However, with this method you are not allowed to dig the ground as it may resurrect the rhizome that has inevitably avoided the poison and gone dormant. That's fine if you have no plans to do anything with it, not so fine if you want to use the land for something.

To the OP's friend, the JKW is 100ft away from the house so poses absolutely no threat to anything. The RICS have done a paper on it: https://www.rics.org/globalassets/r...weed-and-residential-property-1st-edition.pdf so I recommend a read of that. The PCA also have guidance (and I've done their PCA Qualified Technician course).

koolpc · 1 Nov 2019 at 09:18

Rear of garden