New Build Japanese Knotweed

gwilson30019

Evening all,
We viewed a new build this morning and really loved it. The property looks into a nice row of trees and vegetation (approx 9m from the nearest boundary of the plot we like - across two pavements and 5.5m wide road). During the post-viewing discussions with the sales rep we asked about this area and what the plan was with this (as it is currently surrounded by security fences). She then told us it is secured because is undergoing treatment for Japanese knotweed (started in October 2017) and due to last 5 years.
This was a bombshell to me and my wife as we love the house, plot and outlook!
My questions are:
1. Do you think there is significant risk of spread of such japanese knotweed to our plot (9m away)?
2. The fact this infestation is not specifically on our plot - would this be reported in any future home or building survey if we decide to sell?
3. How successful are the 5 year treatments in eradicating the infestation?
We are pretty surprised that planning permission was granted to build on land with a JKW infestation! Seems crazy.
Thanks all!
G

hazyjo

If they've been churning up all that nearby soil for months or years which may well have contained it, who knows where it might have ended up. I would be very concerned.

I would at least want to know what came first - the new builds, or the discovery of knotweed. If the knotweed was treated first, it may be okay. If it turned up after, that's not great.

dexterwolf

I would be running to the hills . As say the developer says they are treating it and then in a year or two sell all the houses . Who is treating it then . Also testing it by spraying it once or twice a year is different to injecting the spindles . 

I would be very careful over the wording of the treatment cycle and also is it guaranteed they will treat till it is eradicated. Otherwise you might find your house is worth far less when you come to sell. 

We looked at a house that had it nearby and the house was sold for 40/50k less than what is was on at . 

gwilson30019

Thanks both for your comments.

GDB2222

What guarantee (backed by insurance) will the developers be providing against JKW?

daveyjp

Is the land due to be developed after the 5 year period?

Mickygg

I'm with hazyjo I would be concerned if its been moved around site. 

gwilson30019

daveyjp said:

Is the land due to be developed after the 5 year period?

No the land is an area to be landscaped as contains a number of trees protected by a tree preservation order. That’s why we originally thought it was a nice outlook! Before stumbling upon the knotweed situation.

gwilson30019

GDB2222 said:

What guarantee (backed by insurance) will the developers be providing against JKW?

The company contracted to treat the Japanese knotweed are registered with PCA and will guarantee for 10 years. Our biggest concern is the potential future detriment to house value? But not convinced we would be legally obliged to disclose knotweed presence on land not owned by us? And importantly, out with the 7m distance regularly quoted.

gwilson30019

Mickygg said:

I'm with hazyjo I would be concerned if its been moved around site. 

The area has been quarantined and treated before any building/developing commenced.

daveyjp

Which means responsibility for any future problems will rest with the landowner.

If this area is to become a common area for the estate the costs could fall with the residents via any management arrangements.