To expect a 5% reduction in asking price because we found japanese knotweed?

Absolutely wouldn't bother me.

Part of my garden has it and I suspect previous owner had a treatment and didn't declare to me when the house was sold. I have far more invasive growing plants and I spray any weak growing knotweed when and if I see it.

If you have a garden, you have to put effort into looking after it.

Reduction in price to the cost of getting rid of it or the current owners commit to removal costs until 100% removed and you'll pay asking price. I'd be more concerned about bamboo these days, at least there are ways to be rid of knotweed.

Japanese knotweed is hard to get rid of but is not the evil plant everyone here seems to think. Buddleia is more damaging. I bought a property with a couple sprigs. There was a treatment plan in place. Sprayed twice and had been checked a couple more times and there's a ten year guarantee. It hasn't reappeared in three years.
As treatment is £2k I wouldn't give you 5% off. But if they are desperate they may take it.

So it's not even actually in your garden? How does that work if it is on someone else's land?

I would check that out and if the property owners of the land where it is aren't in agreement, then I would walk away

Not 5%, 50% reduction for knot weed

Your attitude is sensible, shame to see so many others still so unenlightened.
We bought a property with JK. This was 10+ years ago when hysteria was high.
It was right up against the house. Thankfully we didn't need a mortgage. Treatment plan had been started. Cost shared between the estate of the vendor and the house next door owned by a government organisation who had employed national experts to advise them
The house was in an excellent location and without the reduction for the JK we could not have afforded it so after lots of research we took a chance.
Treatment was successful. We were given a guarantee.
By the time we sold it attitudes had changed and we made a good profit enabling us to buy our dream house.
Go for it

I deal with it at walk and one plant 6m away wouldn't put me off. Check they have not tried to disguise it in the garden though.

I’d only buy it if you intend to live there for a long time.

😱

I would walk away, or at the least knock 20% due to resale value and so I could sleep soundly at night.

I think 5% is reasonable to cover the cost of treatment and for the added aggravation of dealing with it.

You can ask for a reduction for the cost of treating it, or better still ask them to pay for it if possible? If you're planning to stay in the house for a few years you won't even have to mention it when you sell.

The attitude to JK is ridiculous really, it won't make your house fall down and it can be gotten rid of perfectly effectively. Houses get sold with far worse problems than JK. RICS specialists have been recommending that mortgage lenders calm down about it, it really shouldn't be disrupting house sales. The current rules are silly because it means if you're a seller and you find some, it'll just encourage you to chop it down (spreading rhizomes and making it worse) to hide it from the surveyor/buyer and by the time it pops up again you have plausible deniability.

And believe me I know what a problem it can be - we had a bit of a 'mare selling our last place as DH had treated a single stand of JK himself a few years previously and it was just on the cusp of the time when we didn't have to declare it (and we couldn't cover up as the upstairs neighbour knew about it). Luckily our buyer was an experienced investor who was a cash buyer and didn't think it was a big deal!

YYY to every word of this.

I’m a surveyor and a building engineer. People hear ‘Japanese Knotweed’ and freak out.

It’s really not usually a massive problem.

A small patch will be easy to remove. I’d suggest a reduction of 2k, which will more than cover it. If you’re inclined, you can easily remove it yourself.

I thought it was really common as well, I didn't think it was that serious an issue. I've not bought (or more to the point sold) a house for the past 20 years though, so I don't know what's on the forms now and what scares people off.

I would take specialist advice and base negotiations on that. However, the horror stories about JK would be enough to put me off buying altogether regardless.

(Which is why mortgage providers concern themselves with it.

I am certain that JK can be extremely difficult and long winded to get rid of, regardless of the comments.

There's a weird mythology around Japanese knotweed. It's really common and the advice you've received (and your approach) sound sensible.

It sounds reasonable. You are asking for a larger reduction than the cost to remove it but as someone else said you will have to tick the box you had JK when you sell and as you can see from some reactions on here it will reduce the pool of potential buyers.

Personally I'm having utter hell trying to get rid of bind weed. This doesn't damage my property but it takes over my garden in a matter of days. I will now never buy a house with bindweed or any other type of plant known to be problematic like bamboo or JK. It's just stress

Japanese knotweed is really not that bad! My mum had some on an unadopted piece of land just outside her front fence, the most annoying thing was finding out it was close to her house but that no one was actually responsible for sorting it so she paid for a 10 year plan and it's nearly at the end now and at every yearly check there was no evidence of regrowth. It was treated and it never came back. She had no trouble selling the properly either, just passed on all the paperwork as it was still in the process of being treated. She had absolutely no idea what it was and was lucky someone passing by actually recognised it and knocked on her door. But it's really not that big a deal, I would say that's a fairly reasonable request taking into account how much it costs for one of those 10 year treatment plans xx

I honestly have no idea why people are so terrified of Japanese Knotweed. It's really not that big a deal.

Op, I think has answered this:

"5% de-value is what my many google searches turned up....5% being minimum for a small plant not causing disturbance, up to half price de-valuation if extensive. The devalue lies in always having to tick that box on the TA6 form that asks if JW knotweed has ever been present on the property."

We are currently having 2 pretty substantial JK plants treated in our garden which are off shoots from council owned property next door

I’d agree with your assessment that it's not at all the nightmare scenario it's made out to be!

We have one plant being injected and a smaller one sprayed. The company also have a 10 year guarantee which is reassuring

The council are paying about £5k in total to treat the plants next door and ours

I think 5% feels right as although treatment plan may be £2k, if you want to do any digging around that area or lay concrete for a new shed or border work you'd need to engage in this company to come and excavate the area as the root system will need to be taken out by professionals (otherwise it'll die on its own within the 10 years from the treatment). So asking for a bit more off will mitigate these potential costs